Karaganda State Medical University.Karaganda State Medical University. Chemistry department. Chemistry department.

Lecture on the topic: Lecture on the topic:

High Molecular Weighteight Compounds.

For the 1st year students of specialty For the 1st year students of specialty “General medicine".“General medicine".Discipline: Chemistry.Discipline: Chemistry.Lecturer: PhD, Associate Professor Lecturer: PhD, Associate Professor

Vlassova Lenina.Vlassova Lenina.

Karaganda 201Karaganda 20144

The main purpose of the lecture – the study of the features of solutions of high molecular weight compounds, in particular, of protein solutions.

You should be solved the following problems:1 Disassemble the classification of the polymers.2.Be able to describe the polymer solutions. 3. Understand what are swelling and viscosity of the polymer solutions .4. Be able to identify the osmotic (oncotic) pressure in the solutions of the polymers.5. Understand what processes are described Donnan membrane equilibrium.6. Characterize the specific properties of the polymer solutions.

General concepts and classification of polymers. High molecular weight compounds (polymers) -

are substances whose molecules consist of hundreds or thousands of repetitive groups of

atoms. Same, repetitive groups of atoms are called the elementary

unit. Initial low-molecular substance which synthesized polymer is called a monomer. The molecules of the polymers due to their high molecular weight are called macromolecules.

By descent the polymers are divided into biogenic and synthetic. As a result, the activity of organisms biogenic polymers obtained in the biochemical synthesis of the polycondensation reaction (proteins, nucleic acids, etc.).Synthetic polymers prepared starting from low molecular weight substances in the polymerization reaction and polycondensation.

At the core of At the core of protein protein synthesis is synthesis is the reaction of the reaction of polycondensatpolycondensation.ion.

The main synthetic polymers having medical applications include:

1) polyester - polyethylene, for the manufacture of vascular prostheses - aorta, vein;

2) Teflon - PTFE, of it prepare cardiac valves;

3) PVC - of it prepare medical underwear;

4) polymethyl - used to make the jaws, gums, teeth;

5) nylon - for tendons, cartilage, ligaments;

6) blood substitutes - polyglukin, reopoligljukin;

7) diflon - used for the manufacture of thermometers, needles.

According to its spatial According to its spatial structure of macromolecules structure of macromolecules polymerspolymers are: are:linear, branched and space.linear, branched and space.

The linear form The linear form polymerspolymers is very important is very important as this form macromolecules as this form macromolecules causes the flexibility, causes the flexibility, elasticity, mechanical elasticity, mechanical strength.strength.

The ability to restore the The ability to restore the broken form called elasticity. broken form called elasticity. Many tissues of living Many tissues of living organisms (skin, hair, organisms (skin, hair, muscles) possess this quality.muscles) possess this quality.

General characteristics of solutions of macromolecular compounds.

The polymer solutions have a number of properties of colloidal-disperse solutions: they diffuse slowly, do not pass through the membrane, the size of the colloidal particles corresponds to (10-6 - 10-7).

The polymer solutions have several properties of true solutions: they do not have an phase separating border, i.e. they are homogeneous systems, which are stable and can reach a concentration of 10-12%.

• The polymer solutions have specific properties - they have a high viscosity, can easily turn into a gel.

• The process of swelling is preceded by dissolution.

• The polymer solutions capable of such special events as syneresis, thixotropic, coacervation under certain conditions.

Aqueous solutions of proteins

1. The polymer solutions are divided into electrolytes and non-electrolytes.2.Solutions of rubbers, nitrocellulose, cellulose acetate are nonelectrolytes.3.Substances containing a carboxyl group - COOH, sulfo - SO3H and amino-NH2 are electrolytes.4.The most important highmolecular-electrolytes - aqueous solutions of proteins. They are often called polyelectrolytes, since they have two ionogenic groups, the basic -(NH2) and acid -(COOH) by which protein macromolecule shows amphoteric properties.

The proteins behaves as an acid reacts with a base due to its amphoteric properties:

and as a base, reacts with the acid:

R CHCOOH

NH2

+ R CHCHOOH

NaOHNH2

+ H2O

R CHCOOH

NH2 NH3+CI-

+ HCI R CHCHOOH

The state of protein wherein the number of ionized acidic and basic groups are equally in molecule is called isoelectric state (IEC).

The pH at which the number of opposite charge in a protein molecule and its the total charge is zero is called the isoelectric point (IEP) of the protein.

If the pH of the medium different from the IEP, the protein macromolecule are hydrated as they have an elongated shape and charge.In the process of hydration the water is retained of macromolecule of protein. This water is called associated.Than higher the hydrophilic properties of the polymer, it will contain the more water and the more stable solution of the polymers .

the formation of the solvation shell around a the formation of the solvation shell around a charged molecule.charged molecule.

The charge of the protein molecules in solutions The charge of the protein molecules in solutions with various media.with various media.

The phenomenon of swelling of the polymer solutions .

Swelling - the process that precedes dissolution of the polymers.Dissolving of the polymer starts with diffusion of the solvent molecules into the volume of polymer. In this case intermolecular bonds in the polymer are weakened, solvent molecules penetrate into polymer ,gradually loosen it and move apart polymer units. Thus, there is an increase of polymer - polymer swells.

proteins capable to swelling, which can be seen in proteins capable to swelling, which can be seen in the production of batter.the production of batter.

synthetic polymer that can replace the synthetic polymer that can replace the synovial fluid in joints, preventing the contact synovial fluid in joints, preventing the contact of joint surfaces and damage due to friction.of joint surfaces and damage due to friction.

If the intermolecular bonds in the polymer are strong enough and the solvent is not able to divide the molecule, then the swelling stops. Such swelling is called limited. Limited swelling rubber, cellulose, starch in water solutions.

Swelling degree α is a quantitative characteristic of limited swelling polymers and it determined by the ratio of the increment mass (or volume) of the polymer sample (m and V), occurring as a result of swelling to its initial weight (mo) or volume (Vo).

α= (m- mo) / mo или ά= (V- Vo)/ Vo

If between the polymer molecules no strong bonds, it swelling continues until dissolved.The homogeneous system is formed.Such swelling is called unlimited.Examples unlimited swelling polymers may serve as dissolving the rubber in hydrocarbons and the proteins in water.

Biomedical swelling is Biomedical swelling is often associated with often associated with edemas, which may edemas, which may occur as a result of occur as a result of violations of water-violations of water-salt metabolism and salt metabolism and excess water binding excess water binding cell, which is cell, which is observed as a result observed as a result of delays in the body of delays in the body of sodium by of sodium by reduction of renal reduction of renal function.function.

The water in the swollen polymer has two forms:

hydration (associated) and free (capillary), which plays the role of the medium.Bound(associated) water has limited mobility, and it has not dissolving properties, it has a regular structure, it is close to the properties of a solid and has a higher density (1,28-2,45) compared with free water.

It has been It has been established that one established that one of the reasons aging of the reasons aging of the body is the of the body is the loss of the ability of loss of the ability of tissues to hold the tissues to hold the bound water at bound water at normal levels. normal levels.

Typically, young Typically, young organisms organisms contain bound contain bound (associated) (associated) water water significantly significantly greater than the greater than the old.old.

The viscosity of the solutions of macromolecular compounds

Viscosity refers to the specific properties of the polymer solutions. The polymer solutions are

characterized by high viscosity, which is associated with a high molecular weight polymers, flexible chains, the availability of high-hydration of

macromolecules.The viscosity of the polymer solution depends on the nature of the solvent and greatly affects the

shape of the macromolecules in solution.

The relative viscosity is the ratio of the viscosity of the polymer solutions ή to the viscosity of the pure solvent ή0.

ήrel= ή/ ή0

The specific viscosity is given by:

ήsp=( ή – ή0 )/ ή0

The molecular weight of the polymer can be found by Staudinger formula:

ήSP/с= КМ α

where: ή sp / c - reduced viscosity,           M- the molar mass of the dissolved polymer:           C - mass concentration of the polymer in solution (%):           K and α - constant constants for a given homologous series.

In order to characterize viscosity of the polymer solutions the equation Mark-Kuhn-Houwink applicable: [η] = KМα,

where: [η] - the intrinsic viscosity;α - constant characterizing the degree of coagulation of the macromolecule in the solvent (in the form of sticks or globules).

The osmotic (oncotic) pressure.The osmotic pressure of blood at 37C is 7.7 atm. This pressure is the sum of pressures of the dissolved substances in the blood plasma, including proteins.Part of the osmotic pressure due to the presence of proteins, called -oncotic pressure. It is 0,004 atm (i.e., 200 times lower than the osmotic pressure).

Oncotic pressure HMC solutions can be calculated according to the Haller equation :

2KCM

CRTπ

where: C - mass fraction of the polymer;M - molar mass of the polymer;R - universal gas constant;T - the absolute temperature;K - constant, reflecting the properties of the solvent.

Oncotic pressure has a key role in the flow of water into the bloodstream from the tissue fluid.

Donnan membrane equilibrium.

Always in the living tissue along with solutions proteins and their salts,the ions of conventional electrolyte (NaCI, KCI, CaCI2, Na2HPO4, NaHCO3)are also present , which leads to a redistribution of electrolyte and thus affects on the osmotic pressure to either side the membrane. Redistribution of electrolytes membrane obeys the Donnan balance.

)outsideC(2)insideC(

)outside(Cx

2

where: x - the number of ions passing through the membrane into the cell;C (outside) - the number of ions of the electrolyte outside of the membrane;C (inside) - the number of ions of the electrolyte within the cell.

inside

The specific properties of HMC solutions .

You can often to observe gelation in HMC solutions .Essence of its consists in the complete loss of fluidity and solution acquires of hardness : solution turns into jelly or gel.

Gels that are part of the cell membrane and the nucleus are biologically important gels. Vitreous body of the eye - a typical gel ;clotted blood - gel, jellyfish - a living gel (99% of water). Fruit jelly, sour milk products - yogurt, buttermilk, cheese are gels.

Vitreous body of the eye - a typical Vitreous body of the eye - a typical gelgel

Venous clot .Venous clot .

Jellyfish - a living gel (99% of Jellyfish - a living gel (99% of water).water).

Syneresis - is aging of gels. It is associated with loss of associated water of proteins, which leads to the gradual contraction of the gel structure.  Syneresis is observed in blood clot (gel) at 40 C, when the selection is slightly colored, almost transparent blood serum occurs.

Syneresis plays a role in blood Syneresis plays a role in blood clotting.clotting.

The destruction of the gel can be observed by mechanical action.The phenomenon of mechanical failure of the structural network is called thixotropy.This process is also reversible: at rest the solution is gelatinized again. The ability of the polymer solutions many times to gel at rest and during mechanical effect become by liquid is called thixotropy.

Thixotropy.Thixotropy.

Thixotropy.Thixotropy.

The photo shows the The photo shows the gums and the gums and the polymeric material polymeric material from which the from which the sample of tooth is sample of tooth is prepared.prepared.

Due to its thixotropic Due to its thixotropic material does not flow material does not flow down from the teeth down from the teeth of the upper jaw.of the upper jaw.

Coacervation - the separation of a homogeneous HMC solution in two phases. Single phase - is a HMC solution in a solvent , the other - it is a solution of the solvent in the HMC solution .Both layers are homogeneous, but differ in content BMC in each phase, i.e. viscosity. Viscous phase containing almost all macromolecular substances, called koatservant. Coacervation characterized in that the macromolecular substance is collected in large droplets, until there fiber bundle.In the history of life on Earth coacervation process was an exceptional importance.

Coacervation can give Coacervation can give the product as a fine the product as a fine powder, granules or a powder, granules or a suspension with a particle suspension with a particle size from 10 to 800 size from 10 to 800 microns.microns.

The capsule shell The capsule shell insoluble and only insoluble and only collapses by a collapses by a mechanical impact.mechanical impact.

Externally the formation Externally the formation of coacervates looks like of coacervates looks like a haziness or a haziness or opalescence of the opalescence of the solution.solution.

Thank you for your attention.Thank you for your attention.