I want to do today is to
discuss surface interactions

in relation to black compatibility and
what I hope to be able to convince you

of the overarching importance of
protein surface interactions for

biomaterials by a compatibility and

this kind of leads me into the subtitle
for the talk which which might be that.

And so I hope that I think that
one can possibly make a case

that you could design for

by compatibility by controlling protein
surface interactions and since the work

that we have done is mostly inhalation
to the blood by material interface.

I give put those words
into that subtitle So

just to remind you probably this
is necessary for this group.

I'm not sure but mind you of some of
the applications of blood contact but

blood contacting biomaterials.

The first group at the top of the slide
for devices that are implanted

completely within the circulatory
system and the three at the bottom for

extra care for ial blood material contact
systems this is only a partial list of

course there are many more that one could
add to that one of the problems with blood

contacting biomaterials a few of them are
listed there just again to remind you we

in response often involving complement
activation inflammatory response involving

white cell surface interactions infection
is usually lurking in the background.

If one isn't careful the material itself
can be degraded of course the blood and

tissues generally are pretty aggressive
chemical and black chemical environments

and material can on the go with that
predation mineralisation the only involves

deposition of calcium salts on to the
material causing it to become brittle and

then the device to become nonfunctional.

And that's particularly important and
in bio derived by materials the typical

example being the heart of the bio
first I think about there.

I've often from pig farms but
the big the big E.

here has is not on that list yet
and comes in and

to the big problem with blood by material
interactions is of course that materials

in contact with blood will provoke quagga
lation and trumpets from Asian and

never thought there's no material yet
been found it doesn't do that.

Other than the fast killer and
the theme itself.

So that's what we're up against in
this area this show is an example of

an outcome.

I thought but I think our common
catastrophic outcome of contact between

blood and a prosthetic this is a tilting

this cut valve and you can see
that this has been explanted from

the patient when it became nonfunctional
you can see this massive thrombus that

has formed across the opening of the valve
which therefore can no longer open and

close function normally there
which supposed to do so

the real question for us is how do
we get from the sort of innocent.

If you want first contact between blood
and the surfaces of this fall and

this horrible final catastrophic outcome
of thrombus which causes a device to fail.

So how do we do it.

How do we get from there to here.

Well we don't have all the answers to that
but I think one answer we do have is that

all begins with protein interactions
protein it's option putting

sticking on for the surface of the valve
and all the other effects fall from there.

So let's just indicate a little bit
about blood material interactions

blood in contact with a by
material first thing that happens

is that proteins come to the surface and
stick a cover the surface within.

Less than a second.

I would say and
everything else follows from that and

a few of them of are listed
here regulation like cell

interactions platelet interactions
leading to a thrombus complement into

the activation part of the immune response
and even some good things something

that might want to have happen which would
be five in a Lysis or clot dissolution.

That's a natural body response as well.

Later on in the sequence.

So our position here is that
if we can control this initial

event as protein coating on the surface
which is likely least everything else and

maybe we can stop the control this
maybe you can stop graduation.

Whitesell effects and so forth and
promote the ones that we want

to happen by controlling this
initial event that's the position.

That's the proposition that
we're making here and I

don't want you to leave this seminar with
the impression that things are as simple

as you might have got the impression
they are from the previous life.

This is a bit more realistic schematic
of blood material interactions and

I want to take the time obviously to go
into all of these boxes this want to point

out again that things get started
over here with the absorption of

the initial protein lab and
end up over here with the thrombus and

possibly the ambulance if it's
an implant in the vascular system and

all these pathways leading to fiber and
leading to platelet aggregates and

so forth and
there are lots of interactions back and

forth between them quite complicated but
it all begins with protein and so

option and so this will just be discussing
and a lot of research that's gone on

I was over the last more than thirty years
leads us to this very simple paradigm

of tissue material interactions which
is that when you put by material.

With tissue whether it's blood soft
tissue hard to shoe first thing that

happens is you get a little
protein deposited and

then letter later on a bit later on
the cells will approach the surface and

they will interact with the surface in
ways that depend on which proteins they

find there and usually so
the cells will stick or

not stick the stick will undergo a
secondary responses which could be good or

bad but usually in a case of blood
contact them by AD and so knowing this

is the paradigm if we accept that then
following from that we should be able to

say that design for of material for
a given objective which might be empty

like tail ninety clotting whatever
should exploit this paradigm

knowing that this is the first thing that
happens we should be saying to ourselves.

Well that is the interaction we should be
focusing on we must be able to control

that for
a given object of in turn this leads to

a design phase we're concerned at least
in our lab a design principle for

by compatibility based on controlling
protein surface interactions or

took components to this design principle
the first one is that we must try to

prevent nonspecific
interactions of proteins by

the Radnor I'm sure you've all
heard of I said and many occasions

where I've been present that nonspecific
uncontrolled nonspecific protein.

So if the enemy of bio compatibility
the enemy of black compatibility and

I think that's an excellent way to make
that point if you don't stop nonspecific

absorption you're going to get fibrinogen
which will cause platelets taking and

many other things like that.

So you have to keep the proteins off the
surface and I always say at this point and

point I'm discussing this that this
is an unnatural thing to try to do.

We all know about nature
barring a vacuum right.

Well in my view nature also of course

an interface in a biological system
that is not covered with protein.

So we are trying to go against nature by
stopping proteins going on the surface.

It's a very very difficult thing to try to
a few of the ways that people fight and

do this by thatching polymer SIOP usually

hydrophilic polymers like polyethylene
oxide in particular but others as well

that strands all the way up through all
of the On being used in this election.

That's one approach and

also I think the second of
classification of approaches here for

us to look at like polymers or even for
us to look at layers and cells which is

a an attempt to mimic the plasma membrane
of the cell which after all does not.

It's or proteins nonspecifically So
these two things.

I mean ways people have tried to do that.

So that's one point in this one principle.

The second point is that we say
it's keeping all the proteins off.

We might be able to gain some advantage
by promoting and calling the selective

exclusive binding of specified Cortines
what genes that we want to have the A for

one reason or another that we think
will give us a beneficial effect.

And by that ability and I'll give some
examples of that later far and we do that.

Of course by attaching Liggins to the
surface which will capture those proteins

that we want to have them and so

just to go back I'm going to in
the rest of this seminar talk about one

example here and one here from work so

polyethylene oxide is this example
I'm going to talk about and

there's a simple polymer has this to your.

Why is this able to prevent
proteins was taking the surface.

Usually it's grafted on to the surface
at one end and free at the other

that well here to three point to make
here it's kind of feel like it's finally

hydrophilic what binds what the very
tightly usually three hardened bonding and

it's kind of leads to what I call
the water barrier explanation of why

Paul Anthony knocks like keep proteins
away from the surface waters bond so

tightly that when the protein tries to
approach it can't replace the water and

therefore cannot interact with people and
with the surface underneath.

Below is not charged.

So you kind of electrostatic interactions
between the protein and the surface

proteins like to do like to be like to
study interactions they can't do it here.

It's a very flexible chain.

There's Fredo Taishan and on the cover an
option points like convert carbon bonds.

This makes a polymer easily
be formed easily undergoing

change in conformation But if it's patched
and onto a surface it can be pressed

very easily as authorities have told
you and this leads to the idea of.

And which is explained very rather
simplistic them politically.

In this cartoon and so the idea is here
that you have the polyethylene oxide or

other polymer grafted
to your very surface.

This is just showing one chain you have to
imagine course it's a fairly dense layer

of peat your other polymer
the protein comes in and

can't get to the surface it can't
interact with appeal itself so

pushes down and
compresses the chain which is easily done.

I mentioned eventually reach a point
where it can be compressed any more.

There's an energy penalty
in doing that and

this generates a repulsive
interaction effect of.

And the protein is pushed
away from the surface.

So I simplistic explanation whether it's
correct or not I don't think anybody

really knows this point but it looks good
so there are these two ideas the water.

Barrier and exclusion over
the case may be I want to tell

you now about some work that we've done
in this appeal area which is not grafting

the polymer onto the surface but rather it
using polyethylene oxide containing cool

polymers and
using them as additives in polyurethane So

we just mix this little
Pollock polymer component into

polyurethane and
standard polyurethane as a metric and

that turns out to be antifouling and
we've done a lot.

We've done other systems
containing peel but

the reason telling about this one is
it's a very very best and published it.

One thing which is always interesting.

Seven.
I think and half another this is the best

way that we have found to to
do the simplest and the best.

So the approach is to that
we've we've synthesised

Paul ethylene oxide based try block all
polymers with this structure P.E.O.

on the ends and
then the follow us in center block and

then what we do is we blame
polymers into a base ball

the earth in which is then a matrix for
the overall material and important point

two is that the polyurethane in the middle
block of this core polymer as a structure

very similar to the Matrix polyurethane So
that has implications as well.

And so we expect that if we put this blend

in contact the nucleus system
since the POS hydrophilic it

will migrate to the Palmer I should
say will migrate to the surface and

will give us or
anti following the fact resistance fact.

And furthermore that the interactions

will get interactions between the middle
segment of the school polymer and

The Matrix itself and that should enhanced
the stability of the core polymer and

effectively and
help to anchor it at the interface.

Otherwise we might lose
a into the liquid system.

So here are three of these core
polymers We'll show you death on today

you'll see them referred to as one two and
three and the structures are very similar.

They all have the same mental block of
molecular weight about five thousand and

different molecular weight and
block five fifty two thousand and

five thousand and these correspond to this
is the number of ethylene oxide units

twelve forty five one hundred fourteen.

So these are all the Go America I
would say rather than high polymer

so I'll cut to the chase right
away I could show you all

kinds of characterization data and surface
analysis but we're trying to do here is to

demonstrate that we have a protein
resistant non-protein falling material so

here's an experiment where
we look at five minutes and

it's option either from buffer or from
blood plasma and this is how we do it.

The key point is to label
fibrinogen with radioactive iodine.

This allows you to trace it and
to quantify it on the surface.

So that's the protein

in question by bench it's a big
priority the molecular weight

three hundred forty thousand of which is
a major component of blood plasma has

this schematic structure here with
a two D. domains and in the middle.

It's a very symmetric molecule
lank about four sixty in

diameter about one thousand units.

This is if you don't know the biological
function of this protein as.

To be transformed from this molecule into
gel fiber and gel which is the material of

a blood clot and that's what happens by
chopping off those five in a peptide and

a demand and allows the motor
fuel to self assemble into a gel.

So that's fibrinogen and
if we do that experiment I just mentioned

the previous slide this is
kind of typical data that yet

this is a Georgian from buffer
to us buffered ceiling and

their plans of this core polymer with
a peel molecular way is by fifty.

So it's quite good.

Saurabh on the Y. axis and solution
concentration on the X. axis which is

a nice with them effectively that would be
a nice system if it was thermodynamically

reversible which is not that doesn't
take a matter for this discussion.

So here's to control
the polyurethane was no P.E.O. and

this is typical the put into action
rises up very rapidly and levels

off around one microgram pretty quick sand
to me that translates into pretty tight

layer of the range of the surfaces
pretty well covered with a monolith.

As soon as you start to enter just
a little bit of this core polymer and

to the bland your and so

option shoots way down even at a level
of point five percent by weight.

You've lost about one thousand five
percent of your protein wear and

as you blend in more and

more of the core polymer you can't see it
too well in this because of the scale.

It goes down a bit.

So this is a pretty I think convincing for
me at least demonstration of your fact of

innocent this approach to using P.T.O.
to obtain and

then falling surface choice for

more data on that this shows the fact
of Appeal blog molecular weight

on it's option and they are all loaded
at the five percent body weight level so

I've got four surf this year that
control what you saw in the last.

Loyd the same and then the sort of
three blind surfaces containing

polymer five fifty two thousand and
five thousand and you can see that it's

the small of the last molecular weight
down here which gives us the best result.

And as we go up and molecular weight
to two thousand five thousand

they become less effective in terms
of protein resistant resistance.

This is an enforced the fan and
some of protein existence on

electoral weight of the P.C.
or because I see inverse because

other people have worked in
this area using grafted P.E.O.

on a surface find the opposite to that
that I thought molecular weight was up

the surface becomes more effectively non
falling but this is not grafted surface.

So maybe it isn't surprising
that dependence is different.

We don't have the explanation for why
this point I may simply be that the lower

molecular weight materials can corrode
better into the into the surface and

give you better coverage of you or

with an outside unit where you get
transported fact whether more.

Molecules of the smallest assemblies
can move faster to the surface.

We actually don't think that's
explanation but it is a possibility.

So that's that's from buffer the real
true test of putting existence of

course is to put the material
into a real biological system.

And here's some data for plasma now
the sources have been placed and

LED plasma and this again is

the polymer one of peel molecular
weight like fifty the best one and

the control which looks like that
plasma system and the cool polymer

blends with Coppola much lauded and
these percentages weight levels.

So this is again a Georgian
quantity on the Y.

axis and it's a percent plasma and
the X. what we do here is.

We take undiluted class
one hundred percent and

then we see really diluted with T.B.'s and

this gives us a kind of equivalence
isothermal plasmas situation but

the main point in our C.S. is that there's
a huge difference between the control.

And the blended materials and
a huge decrease in fourteen Viney

in blood plasma and so they stay another
demonstration that these things work

quite well it may be of interest to some
people to talk a little bit about this

peak here this is the end for
most maybe from any fact peak and

how many people here are fed of
the Roman effect not to manage.

It's fitting in and it's and
from his push that well this is this

what you typically see for five Ranjan
its origin in a plasma system and

it reflects the fact that the fibrinogen
which is an abundant protein in plasma

tends to be absorbed and
abundance initially and later on.

It's kicked off the surface by
other proteins which are present

at low concentration in the plasma but
have a higher in affinity for the surface.

That's this is actually not time
access but it transposes that way

anyway as you see there's no Roman effect
whatsoever on those blended materials and

so even if very low plasma
concentrations and small times.

There's just nothing on there.

Its surface doesn't want to its orbit and

we've also done a look the other
proteins and flies way and

this allows me to introduce or one of
our other techniques that we use and

blood system to plasma systems and that is
to do this where we expose the surface to

plasma and then we look at our
proteins using a target in this case

as the S. and we take diluted proteins and
we run them one gels and

Adana fight the proteins blaming
the blood analysis and the show.

Some data for some of those blended
surfaces just using antibodies to

a limited number of
proteins fibrinogen albumin

complement C three and apolipoprotein one.

You may not be familiar with this
one too much but we have fun.

The recent work of this this protein is
is there in spades and huge amounts and

many many surfaces that we look at and
we think this is something

that hasn't really been given enough it-I
tension in the community over the years.

Apple way one is the main Apple protein
on the high decibel of a protein

particle weather and so
much of this reflex and

so particle or just the apple protein.

We don't know.

And if you let me show you the data for
those a plant it surfaces again.

So again we're looking at the best
of the bunch here the peel five

fifty molecular weight.

This is the control with no peace deal
with five percent Piola ten percent and

the twenty percent and
the lands are these of standards of course

the lands of this this is fibrinogen
This is C thirty L B M and

forty one and I don't want to
go into detail again on this but

you can see that the densities this is
controlled quantities of protein and

tell you it loaded on to the gels
there's a high density of standing here.

It's last when you get to five
percent land even last year and

here there's nothing.

This is just a background
which comes from the fact

that the person who did this didn't wash
long enough after the procedure to get rid

of the black on black or
no proteins detectable at all.

You know this is really in my view
remarkable result in jail which we've

never seen and I think before you know
it's probably politically incorrect to

brag about when so and data but But what
this really and this really impresses me.

OK Now proteins.

I said cells come after the proteins and
that's true.

Here are some data that pertain to that
this is an experiment where we look at

pro plate look at he and five engine and
so often in the same experiment

and this time it's of course from a whole
blood system and underflow conditions.

This is for lighting like in time.

So anyway this is so we have one this axis

platelet density on the surface on
this axis the fiber engine numbers

we have seven surfaces three
of them are over here based on

the five fifty molecular weight peel
loaded at one five and ten percent and

these three are for the two thousand
the bigger molecular peel one in ten and

then the modified P. you control and

you can see that the two
phenomena follow each other.

Track each other quite nicely.

You have the platelets in the blue
bars in the five bridge and

then the red dots cause the scales of
choice and so that they sit on top of each

other like that but anyway that these two
things track each other quite nicely as

you would expect low fibrinogen low
platelets high fiber age unlikely.

And that's likely what you expect.

So this suggests that when
you do control the protein.

It's origin the cells kind
of look after themselves.

So what is the nature of the just to
go a bit further with this of this

of the material equips interface on this
material that makes it such a good one.

Falling surface and in particular
how was the polyethylene oxide

displayed at the surface to make a sap and

well again the short answer is Not really
no we have done some investigation.

Try to look at that.

Here's something that you total
an expected to give you information along

those lines the scanning E.-M. of
the surface of a twenty percent blend of

P.E.O. five fifty core polymer after it's
been extracted with tell you in now.

What's the significance of
telling an extraction that is

that the core polymer is so you will.

And tell you and the matrix is not so the
idea here was to try to get a handle on

the location of the core polymer
in the blend and sure enough.

So what you see here is is holes or
pits in the surface.

Presumably where the peel component has
been extracted and this is ten microns

across so the whole of the pits are one
to two microns in size diameter which is

typical of micro domains that you find
in blends of two homo polymers so

it looks like the blends have this
typical microstructure of micro

domains of the two to one to two micron
size this experiment with a matrix that

doesn't have any P.T.O. that first just
a blend surface you don't see anything.

So that's what it looks like now if you

look at the effect of telling an
extraction in five minutes in its arch and

that shown here is the same materials
I showed in the last slide.

So if you measure five range and so option
on the matrix material with no P.E.O.

you find that doesn't make any difference.

You get the same high fiber engine and so
action whether it's extracted and not if

you do this on those blended materials
with the five fifty two thousand and

five thousand material you find
that the low protein and so

option before extraction shoots
up dramatically and recovers back

to the value that you had before you
blended this peel component in so

there's no doubt that the tell
you an extraction is removing.

Component is another piece of
information that helps us to think about

the interface.

This is a max P.S. data an oxygen content

at the surface of these two thousand
people molecular weight Bland's So

it's atom percent oxygen and
this is the loading of core polymer two

into the blends by the way the blue bars
are the expected bulk concentration.

So this would also be
the surface concentration.

If you could polymer is uniformly
distributed through the through the matrix

and you see that goes from
abut seventeen percent here.

This is the matrix with nothing no pos it

up to maybe nineteen percent with
with twenty percent of the call for

the blend and then if you do that if
you look at the X. P.S. data itself

taken in one hundred degree take off
angle you see that these pink bars

way above especially the high
loadings are way above the bars and

the killing and enrichment of P.T.O.
will surface as you would expect.

And if I can you get to this one a twenty
percent one you see that the numbers about

twenty six percent of oxygen and
that is exactly the same comp.

I think percent that you have
in the core polymer itself and

that suggests that the surface here is
completely covered by the core polymer and

that composition even in the high
vacuum atmosphere of the next P.S.

machine and so
again as I say this this is ongoing work.

We yet have to come up with
a satisfactory structure for

this interface but here's one idea.

And this would be like a cross-section
cut down into the material Now

we do have this domain structure
we have to deal with that

we have to deal with the fact that if
it's like this on the surface then that.

All kinds of metrics surface
which is not about P.

on it which I did sort of a lot
of protein based on other data

and so what we're saying I think is
that right at the interface here there's

there's something that's
quibbling to a complete layer of

the core polymer and that's what gives
us a very high protein resistant

characteristic of course we extract this
with tell you and that will be removed and

you'll be left with
the distribution that you see

now that's that's about as far as I
can go with that I want to know for

the last ten minutes or so
hopefully not much more than that and

go to the second part of my design for

for my compatibility based on
controlling protein absorption so

here I am saying what I'm saying
is that we can hope to design

by a functionality enter surface by
controlling protein and sorting as well.

And this gets us into trying to
capture specific proteins from

the biological system and so.

So here are some examples of things
that you might want to do in the flood

compatibility field that we can make
this happen and all the details.

The idea is that you decide in some
kind of functionality that you want and

then you say what protein.

Can I get on my surface that's going
to do that for me that's over here and

then having made that decision.

You need to figure out a lag and

you can put on your surface
to capture this protein.

So that's kind of the with
the algorithm if you want I'll

talk about just one example here and
this is the one down here where we want

to have a five an Olympic surface a clot
dissolving surface that means we'd have

to catch of the components
of the fiber LET IT system.

But Jeff lives mention and
placement and activator and.

I know that there's strong affinity for
those two proteins

in the other part of life seen single
amino acid liason very simple.

So I talk about life in director
of a Tyson polyurethane as

a cloth lighting surface.

The idea here is that for decades now

people have been trying to design surfaces
that will not provoke quagga elation.

So in a sense what we're saying
is OK We just can't do that

we would give up can't prevent
quickly from from happening so.

So a lot of to happen and
then in the process of that happening.

Will this will trigger for us the process.

There's also a clock before it
gets too big or too problematic.

And I should mention that the actual we're
going to talk about years of collaboration

with somewhat excess and
Minneapolis the objective is

again is to develop a clot liason surface
which would have the ability to lice

incipient nascent microscopic clots
before they become a problem.

I think the approach is to have
a surface which is selected for

binding and
dodgin as players manage and T.P.A.

the components that you need to
dissolve clot we'd find these

components via lysine present use
incorporated into surfaces and

of course we need to have
the placement of be activated

to plasma which is the clot dissolving end
zone on the surface that has to happen.

So I just remind you about
the five elliptic system this

is a system in the body which dissolves
clots after the no longer needed.

You want the blood to clot and

plug up the breach in the vessel wall but
after a while you don't want to be there.

You want to disappear so it dissolves.

And so here's the end.

So I will five and clot its act.

Upon by the enzyme plasma which breaks
it down into small fragments five and

degradation product placement is not and
blood normally last minute you know this

and so is the activate the T.P.A. as you
please mention activate I and others.

This is a main one.

And so you need to transform
plays menage and into plasma and

not to get this action in
dissolving a clot and so

our idea is OK let's get a surface which
catches this protein and this one and

will have the components of fiber Lysis
on our surface available to act if a clot

ever happens to form and
we know it well and so

what about place minutes in the key
player and this is this is a schematic

layout of the protein it has a ninety four
thousand like you awake concentration and

plasmas point why one five and
we come from L. It's not a trace protein.

It's not superabundant either regions of
five of them and two in particular one and

four bind with hyphenated to lysine
five and clot Lycinus reducing by clot.

It's convert this is converted this is
an active against clots that has to

be converted to plasma with T.P.A.
that involves breaking a single path

I'd been right here and that's the only
difference between plasmid agent and

plasma and this opens the molecule up and
makes this.

And so on activate here
available to act on the clock.

So that's the basis of this material
that we're working on to do

this to be clutch loading again or
based polyurethane So

this is either standard poly or
think components and the piano

and ethylene Di mean as a chain extend
the components are shown done here.

You can distinguish the different
colors it's not too important.

Lysine is incorporated in a courting
reagent this is the this is a somewhat

explorer of this project called The only
tax the polar thing and using for

chemical methods a little bit
more about how the Lysine

is incorporated there are two ways
there that I fasten to the AL.

I mean group of lysine Lysine and
it looks like that chemically the term you

know groups and Alpha and epsilon and
you can therefore attach it to

your quoting agent or
through this one of this one and

then once having done that you
have it with U.V. light and

attaches to your base probably within and
gives you a nice coat so you can do that.

Wait for it.

You can attach it clear the alpha
through the excellent I mean grow up and

leaving the alpha.

I mean free and the distinction between
this one this one very very important

because this is what lysine looks like and
the clot right this often means

group is involved in forming a peptide
chain so it's this one that's free and

this is known to be active in binding
players manage and this one is not

you need to have the freak out
about silicon acid growth and

Absalom means separated by
this is it doesn't see it for

this lysine residue to interact with

Kringle lysine binding site one and
four on his management.

That's well known so
we expect this to be used as a control.

If you want it has lysine on it.

It's all the other component.

It doesn't have the absolute
mean cook free.

This will be the control and
this will be hopefully at the surface.

So again cutting to the chase.

Let's look and see if this indeed
does apply and plays mage and

from plasma if we want to
do the same experiment.

Showed you for five minutes when
we yell label applies manage N and

I get back to the plasma and look at the
uptake onto those different surfaces of

data on that this is already published and
so it's and

so often applies message in this time and
percent plasma on the X. axis.

This is the force or says this is
the control which has lysine on it but

in which the Alpha I mean group
is free but not the absolute and

that's on the title and there are three
surfaces where the with lysine on

them where they actually mean a group
is free but different that's it.

It's interesting to look.

Compare this the black
one with the green one.

They have the same density of lysine

namely pointing in animals per
square centimeter this wanted to.

Obs hardly any in this one.

And so absent a significant amount of like
this factor of about twenty difference

between the choice of the really act
with the specificity of this affluent I

mean a group as a combination
finding fly through an engine when

we're off at this dance of the year and
a hundred percent flies.

We have a monolith here of
management based on this number

which suggests that maybe a wise manage
an unfair little else on that surface

great but
we can show that in fact to be the case by

doing this exposure to
plasma illusion with us.

The US and then run running shells and

lots of some data from that
I want with the details and

this therefore penalties are all in
you know lots using antibodies to

the proteins which I'm sure you can't
read the names of along the top and

this this panel is for the fall of
the earth and not modified at all.

This is for the polyurethane that
has the quoting polymer on it but

no Lysine and this.

One has the Alpha I mean
group liason three.

This is the one to P.S.
to resist Also if you want here which

has the same density of lysine again but
with the Absalom in a group of

vailable here and not here you can
see that pretty well these other

these three surfaces here absorb
everything you can see them all there.

The one with the absolutely no lysine up
three and so abs a lot of players manage

and all a bit of albumin But
the fact the little thing else.

We didn't really design this sort of
has to be resistant to all proteins

except legs mentioned but
that's was it serendipity or

something and we have a lot of placement
in a nest and we need P.P.A. as well.

Third to generate plasma.

So we will look we are interested in
office surface would pick up P.P.A.

from plasma we had tried to find it
with him in a blots but couldn't.

Probably because T.P.A.
is only an plasma a very very low

concentration five nanogram for M.L.
something like that.

So here's an experiment
where we get purified T.P.A.

and we're a label that
with itin one two five.

I did it back to the plasma and
full of the uptake.

And we're going into too much detail here

you can see that here
the controls over here.

This is the Alpha lies in surface.

This is the equivalent absolute lysine
surface and you can see a very significant

difference in its origin between
those two so it looks like this.

Lysine surface has the capacity to
pick up P.P.A. as well as the T.P.A.

is available to pick up this is all
very well the idea is to have a clot

dissolve and surface so the last question
I want to mention of disgust years.

Does this can this surface
dissolve clots for

ten designed to be able to do so we've
got this assay that we work we develop.

It goes like as follows.

When Georgian staff exposure
surface to pull normal plasma and

we know from other experiments that we've
done that will pick up a lot of places

mentioned from the plasma
when we do that then

we wash it carefully and we activate the
plies image on the surface by exposing it.

P.P. a black concentration and
for that much time so

no we assume that we have
a surface that is corded with

and that you feel that is all cloth.

So we watch that carefully to
get rid of all the T.P.A. and

then we form a clot there on
the surface by fresh plasma

situated plasma to the well and recal so
fine and a lot of clot to form or

not form or form and
then we dissolve we see what happens

and the way we do that is to measure
the organs in a cube that four or

five nanometers and we full of that for
thirty minutes body temperature

and of course as the clock forms your
brought up the light will be scattered for

those conformant want change.

If the clock dissolves the absorbance
will come back down again.

Typical data from one
of those experiments.

So it is clot from Asian
dissolution plasma

expressed as absorbance versus time.

So for surfaces to controls this
is the rad one is the public

quoting reagent with no lysine in it and

the blue one is the Alpha mean for
the lysine So this one and that we

have two surfaces a low density lysine
surface with absolutely no purpose three.

That's this one and
higher density of the same just one.

So here's your time.

It's where you had the calcium back
in the clotting can begin at will and

you see it takes a few three or four
minutes for things to start happening in

the controls the absorbance just
goes up then as a ship curve and

levels off and
stays constant and over time and

the same thing basically happens
with the alpha mean the lysine but

which does not yet
let me go free and therefore has not

picked up the placement in an interview
with the active surf is done here.

The clock begins to form but
then again point in time not too far into

the time that scale kind of turns over and

comes back down again and goes back in
fact all the way to the baseline showing

that the clock at least absorbance
has been back down again.

So it looks like in fact that this we take
this at least as a good demonstration of

the fact that the sources do have
quite dissolving beliefs that

this is what that experiment looks like
if you do it this way might be six or

seven or eight minutes into
the experiment something like that.

This is just a plasma with no surface and

you see the cloth as
form it's got all cloudy.

This is the Alpha lysine surface or
there's no way

fact it's basically the same as that they
had finalising surface at that point.

This is only the clot he has formed and
then is beginning to re dissolve and

it takes place at the surface and
this fund if you follow it in time will go

progressively from the surface right out
to the occupy the entire volume of this

event so that's that's a evidence so

far that this is the the club of these
are some of the conclusions from this this

part of the work I want to restate
them I think would be obvious from.

So that.

And over all

what tried to tell you in this just
in this seminar is we believe that

control of fourteen surface interactions
is a filed approach to designing for

by compatibility so I should say that Q.E.
D. or something to that.

Why not now.

OK so I'm done with the science.

I have to acknowledge a whole bunch of
coworkers here these are my Probably and

recently at my last or people at some
wanted to have been involved in this

plot resolving surface work and
other people that Sweden is work it didn't

mention Of course funding from Canadian
government agencies and industry as well.

I'm not quite done but
this is a campus of last University and

from Hamilton Ontario Canada which doesn't
look like that right now look pretty white

right that well this is the medical
center which dominates the campus.

That's the thing that picture this
up here is the Niagara Scatman and

this is the same geologic formation
that Niagara Falls forms apart.

So if you follow
the escarpment that way and

it sort of comes back like this way for
me.

If you come to Niagara Falls
which is only fifty kilometers or

so all done the road from our campus.

If you come to visit McMaster you get the
added bonus that you can take an afternoon

off and going see the falls which
is a very nice thing for the and

finally those of you who know accents.

Well know that I'm not a real Canadian

figure that I'm really
a Scotsman masquerading as.

The Canadian supporters to some extent and
this this picture is of the campus of

the University of Glasgow in Scotland and
I was a student a long time ago.

Quite a long time and
I think about it and the statue

in the front here is of a very
very famous scientist probably

the most famous professor who ever was
a professor at Glasgow University and

in one thousand century and I want to know
if anybody here can guess who that is

I'm pretty sure you don't you
wouldn't norm from the statute or

maybe even from the fact that he was
a professor at Glasgow University but

I know you know what you're
going to be absolutely amazed.

Maybe amazed that I'm
thirty something else.

Nobody not famous the most of very
very famous scientists everybody who's

a scientist or you know a science student
I sort of hostile give you some clues.

Well I said one thousand
century already and a physicist

thermodynamics a towering figure
in one thousand center science.

Nobody knows.

William Thompson who said this or

otherwise no as that nobody's heard of
William Thompson like he's also known as

Lord Kelvin the agree that he's a Turing
figure of one thousand century science.

OK I'm done.

The thank you very much.

Rest assured that

I just can I just gave you an idea right

there on the surface

very remarkable.

We still have people like that

so my question is there
are services like things like

the response.

Well I think that to to to
point to answering that one is

I think that as you say there's other many
other things have been tried dextrous for

example a lot of vile per dollar dollar
on other hydrophilic polymers I think

polyethylene oxide has given the best
results not just what we've done but

other people as well I think feeling and
various guises in various

techniques has given the best results the
most Cortinas so officers but you're right

to point out that noise over time you
know is this going to last or do we

need something else to make it permanently
from the research that's putting.

System and it may well be that
things like the fossil inputs or

the fossil it like
polymers these new M.P.C.

polymers that the Japanese are using for
example might be better.

It remains to be checked out.

It really does but you're right to say
also that there isn't any surface that

resist protein that gets it down to zero.

Within the limits of the texture.

So so I this is correct.

What you says is right.

We haven't got there yet and I think we
do need to get lore than we have got at

this point you know Tom Margaret
says you need no more than five

nanograms I think is a fibrinogen per
square centimeter to prevent platelet

that's a pretty small amount by going
into I'm pretty sure we're not there yet.

Yes.

Yeah

I well we don't have a lot
of information on that yet.

What we have done is to immerse some
of these materials in plasma and

for as long as a week and

we we then have checked whether
the protein uptake is altered or not.

And that's not so
they are stable at least for

that moment of time if if
there really are these

Michael Fay separated
structures that I showed with

a with a strong you know layer of
Peace Corps polymer at the surface

that might because they are somewhat so
it will not really highly so it will.

They're somewhat soluble in it closely.

So it will.
So

effectively it would be a renewing
surface if that's the case that you.

A losing appeal component
from the surface but

it would regenerate from within
the bulk of the limit of course

reasonable you deplete at some point so
that that's about all I think you can say

but yes there is that possibility that
this is leeching only but would be slow.

I think that's why if you just put P.T.O.

itself into something like
that it will be lost.

Very very quickly within
hours will be lost but

that's that's the idea of the core polymer
and especially the polyurethane and

center block with a poly within meters.

Well

that was one thing that we thought of
when we first saw this inverse molecular

dependence so it could be just we still
don't really know if that's true or

not that sort of one argument
against it is that if

you do contact angle
measurements on the surfaces.

If you look at angle kinetics over
time which follow the contact

angle over time you find that
you get the same kinetics

whether it's the high
molecular weight of the law so

that argues against
the transport explanation but

it's it's a question I can't give a and my
answer is I don't know that any transport

specialists in here that we
could address that we're not.

Yeah these fish of this is speculation and
I process.

Now I mean I've seen us
this morning thing before.

I'm not sure that people believe that too
much anymore but that we're groping for

socialism and you know most people
as I say find like a way to penance

is that you get better not falling
as the molecular weight goes

up it levels off but when you get
to something like two thousand.

You don't get any additional benefit
by going higher than that but but

the lower once you know the small
ones like my first it was twelve P.

units would not be as
a factor of two thousand.

If it was a graph that surface
with the same test but this.

These are unanswered
questions more than that.

So

one

might argue.

Well that's right.
I mean they have their objectives are

different and tissue engineering you want
the cells to be on there and happy and

interacting in a beneficial way and
prospering and proliferating and you need

to put inserted do that so on on falling
surface obviously and would not be.

I think it might work.

I don't know it's hard to say
it may well be just great.

You know us but
you know ab initio on the face of it

knowing what we know all that
we do want intimate contact.

We do want and which is usually takes
place through a protein intermediate right

in the case of cells putting out
the one matrix and so forth and

if the proteins don't want to be there
then that's probably not a good thing but

if we also incorporate the idea
that we want just those specific

proteins that are the right
ones to have then this is OK so

it's it's it's both components
of the design principle.

No one falling only only the proteins
there that you want to do.

There is nothing else.

I don't think that's in front like OK

I

know

this shouldn't supply answers and
I don't know any reasons for it.

It's surprising that which is
a shortened life stance plan for

the platelets or or
is it that they see create undergo

their lease reaction
even though they were.

Permits well known in general
that platelets surface.

While you've worked on this area to
think which players have a surface but

they don't state.

Yes they're still altered and

yes yes that's right.

Course which of course

but the implication was very.

Yeah they're the ones you're
talking about we're public surfaces

because we are in the process and

they don't have the yeah I think
definitive to say about that.

Yeah right.

Yes yes.

So I you know I don't know but there's not
a piece of plate little alterations or

not he's of interactions of platelets
with sources is a well known phenomena.

You know and you can get

adverse effects on the platelets without
having them stick permanently and sort of.