生物分離工程雙語(yǔ)版

Chapter

7Adsorption

influence

onbioseparation

andinactivationI

Introduction1

Adsorption

of

proteins

at

interface(1)

Biosensors(2)

Immunoassays(3)

Drug

delivery2

Attention(1)

Determination

of

quantitative

aspects

of

proteinadsorption(2)

Biological

behavior

of

proteins

at

solid

surfaceA

NatureB

StateC

Conformation

and

orientationD

Time-dependent

structure

changesSome

parameters

of

influencingproteins-surface

interaction1

Electrostatic

interactions2

pH3

Surface

charge4

Co-adsorption

of

low-molecular

weight

ions5

Isoelectric

point6

Intermolecular

forces(1)

molecules-molecules(2)

solvent-solvent

interaction(3)

strength

of

functional

group

bonds(4)

chemistry

of

solid

surface

and

morphology·Proteins

in

solution

diffuse

to

interf1

Thermodynamically

favorable

process2

Conformational

hydration

energy

lost

at

interface.3

Initially,

at

low

protein

concentration,

no

barrier

adsorptidiffusion

controlled4

At

high

surface

concentration,

activation

energy

barrieradsorption(1)

Electrostatic(2)

Steric(3)

Osmotic

effect

close

to

the

interfacial

or

surface

layers(4)

Rearrange

at

surface

is

rate

determining·Adsorption

of

proteins

at

interface1

Proteins

at

gas-liquid

interfaces

are

in

an

unfoldpartially

active

or

inactive

state(1)

Conformational

stability

of

flexible

segments(2)

Interfaces

are

primarily

responsible

for

proteininactivation(3)Shear-associated

damage

is

severe

at

gas-liquid

interfaceA

pumpB

centrifugesC

ultrafiltrationAdsorption

of

proteins

at

interface2

Proteins

undergo

a

change

from

globular

conformation

to

anextended

chain·

3

Adsorption

of

proteins-enzyme

at

interface

is

a

complexinterfacial

chemical

reactionkinetic

adsorption

and

desorption

mechanismsphenomenon(1)

transport

to

the

interface

by

diffusion,

convection,

miand

shearing

action(2)

adsorption-desorption

at

interface··(3)

structural

change

of

molecules

in

contact

with

interfac(4)

adsorption

competition

between

molecules

of

differentnature

or

molecular

weightFactors

of

influencing

proteinadsorption

onto

surface1

Protein

adsorption

kinetics2

Chemical

equilibrium

between

interfacialprotein

and

solution

proteins3

Flow

of

protein

past

adsorbing

surface4

Conformation

of

proteins

in

the

adsorbedlayerExample

7.11

Some

positive

influence

or

consequences(1)

stabilization

of

microemulsion,

pharmaceutical

creams,lotions,

formulated

foods

and

foams(2)

protein

purification

strategy

developments(3)

drug

delivery

systems(4)

biosensors2

Some

negative

aspects

of

protein

adsorption(1)

thrombus

development

on

blood

vessels

and

in

artificialimplant

materials(2)

fouling

of

kidney

dialysis

membrane

and

in

processingequipment(3)plaque（飾斑）

formation

on

teeth

and

dental

restorativUnderstanding

proteins

adsorptionstructural

rearrangements

in

protein

molecuredistribution

of

charged

groups

in

interfalayerprotein

surface

polaritydehydration

of

sorbent

surfaceII

Adsorption

of

proteins

and

otherbiological

macromoleculesA

.

Surfaces

for

protein

adsorption1

An

excellent

protein-resistant

surface

adsorption-PEO(1)

Steric

stabilization

effect(2)

Van

der

Waals

attraction

is

small

compared

with

stericrepulsion(3)

Weak

hydrophobic

interaction

between

the

PEO

layer

andprotein2

Sedimentation

volume

method

(Vsed)

to

characterize

thesurface

tension

of

protein-precoated

polymer

particlesB

Monolayer

adsorptionMechanism

of

protein

adsorption

to

surface(1)

Attachment

of

different

amino

acid

residues

to

surface(2)

Interface

will

initially

accommodate

protein

molecules

thhave

the

largest

diffusion

rate

coefficient

and

mostabundant

present

in

solution.(3)

Initially

adsorbed

protein

molecules

may

be

displaced

byother

protein

with

higher

affinity.(4)

Isotherm

(

A

langmuir,

B

Freundlich,

C

Henry’s

law)(5)

Many

adsorption

systems

is

represented

by

monolayeradsorption

systems(6)

Second

and

higher

layer

are

formed

primarily

by

interactiobetween

molecules

of

the

liquid

mixture

themselves.Example

7.3

Quantitative

and

qualitative

features1

Adsorption

process

was

monitored

by

reflectometryand

by

streaming

potential

measurements2

Sequential

and

competitive

adsorption

amount

fromflowing

solutions

never

exceeded

values

ofmonolayer

coverage(1-2ng/m2)3

The

effects

of

molecular

size

and

diffusioncoefficient

on

adsorption

preference

are

practicallnegligible4

Hydrophilic

surface

adsorption

is

largely

determinedby

electrostatic

interactionHydrophilic

surface

adsorption

Protein

amount

adsorbed

from

single-protein

solutionincreases

with

increasing

charge

Sequential

adsorption

occurs

only

if

the

second

proteinhas

a

more

favorable

electrostatic

interaction

The

final

composition

of

adsorbed

layer

essentiallyconsists

of

the

protein

that

has

most

favorableelectrostatic

interaction

with

the

adsorbent.(4)

Initial

adsorption

rate

stages

are

not

significantly

affeby

the

nature

of

the

surface,

at

later

stage,

surfacebecomes

crowded

with

protein

molecules

andresult

in

heterogeneity(5)

At

hydrophobic

surface,

electrostatic

interactiondefinitely

do

not

dominate

adsorption

processSurface

reaction

of

protein

adsorption1

An

exchange

reaction

takes

place

in

proteinadsorption2

Long

protein

molecule

resides

forms

all

itspossible

bonds

with

a

surface

result

inconformation

change

and

stronger

bonds3

Three

types

of

protein

surface

adsorption(1)

Exchange

reaction

and

reversible

adsorptiontakes

place

with

small

conformation

change(2)

Only

exchange

reaction

occurs(3)

At

least

one

kind

of

protein

molecule

is

irreversibadsorbed

on

the

surfaceThermodynamics

of

protein

adsorption1

longer

the

polar

chain,

the

greater

the

endothermic

value2

Protein

chain

increase

ΔH

changes

fromexothermic

to

endothermic

at

higher

degrees

of

coverage3

Dispersion

component

and

surface

energy

determine

proteinadsorption4

The

lowering

of

the

free

energy

is

the

driving

force

and

givrise

to

the

unfolding

of

the

molecule

at

the

surface5

Desorption

isotherm

shows

a

hystersis

curve

and

does

notfollow

the

adsorption

curve.Thermodynamics

of

protein

adsorptionThermodynamic

driving

force(1)

two

positive

entropic

contributionsA

an

entropy

gain

due

to

dehydration

of

proteinsurfaceB

an

entropy

gain

due

to

adsorption(2)

Two

enthalpic

effectsA

positive

one

associated

with

dehydrationB

a

negative

one

due

to

interactions

with

thesolid(3)

Total

entropic

effect

dominates

and

proteinadsorption

is

entropically

drivenD

Adsorption

parameters1

Electrostatic

interaction2

Isoelectric

point

(maximum

protein

adsorptionaround

the

isoelectric

point3

pH(pH

values

away

from

the

isoelectric

point

ofprotein

will

increase

electrostatic

repulsion

leadsa

smaller

amount

of

adsorged

protein4

Negatively

charged

surface

(negatively

chargedBSA

molecule

has

a

higher

affinity

for

the

negativelycharged

polystyrene

surface5

Surface

chargeD

Adsorption

parameters6

Coadsorption

of

low

molecular

ion7

Intermolecular

force8

Solute-solvent

interaction,

strength

offunctional

group

bonds9

Chemistry

of

the

solid

surface10

Morphology11

TopologyIII

heterogeneity

in

protein

adsorptio1

Heterogeneity

of

surface(1)

Significantly

influence

adsorption

and

reaction

onsurface(2)

Influence

the

rate

and

extent

of

protein

denaturation2

Heterogeneity

influence

protein

adsorption(1)

Heterogeneity

in

solute(2)

Heterogeneity

on

surface(3)

Models

incorporating

Heterogeneity(4)

Implications

of

this

heterogeneity

on

protein

adsorptionreactions

on

the

surface3

Distribution

model

of

thermal

activation

energy

fordeactivationIV

Techniques

for

qualitativecharacterization

of

protein

adsorptA

Ellipsometry

Make

more

quantitative

information

aboutadsorbed

protein

films(1)

Thickness(2)

Refractive

indices(3)

Specific

amountB

Total

internal

reflection

fluorescenApplication(1)

Flowing

solution(2)

Measure

adsorption

kinetics(3)

Relating

TIRF

fluorescence

signals

toprotein

surface

concentrations(4)

Examine

initial

adsorption,

desorption

andexchange

kineticC

protein

fluorescence

and

circulardichroism·

1

Far-UV

circular

dichroism

spectraOnly

minor

change

in

the

protein

secondarystructure2

Intrinsic

fluorescenceReveal

tertiary

structure

level3

Low-angle

X-ray

and

neutron-scatteringtechnique4

Enzyme

methodC

Probabilistic

analysis

for

proteinadsorption1

Langmuir

isotherm

only

is

a

macroscopiccharacteristics2

A

stochastic（推理的）

approach

is

capable

ofproviding

more

details

about

a

dynamic

system3

Statistical

analysis

model

the

transient

behavior