物理药剂学-课件

1、Colloidal dispersion systemColloidal dispersion systemClassification of dispersed system based on particle sizeclassParticle sizeCharacteristics of systemexampleMolecular dispersionLess than 1 nmInvisible in electron microscope Pass through ultrafilter and semipermeable membrane undergo rapid diffus

2、ionOxygen molecules, ordinary ions, glucoseColloidal dispersionFrom 1 nm to o.5 mNot resolved by ordinary microscope (although may be detected under ultramicroscope) Visible in electron microscopePass though filter paperDo not pass semipermeable membrane Diffusion very slowly Colloidal silver sols,

3、natural and synthetic polymers, cheese, butter, jelly, milk, etc.Coarse dispersionGreater than o.5 mVisible under microscopeDo not passthough normal filter paper Do not dialyze though semipermeable menmbraneDo not diffusionGrains of sand,most pharmaceutical emulsions and suspension, red blood cellsC

4、lassification of dispersed syTypes of Colloidal dispersion Types of Colloidal dispersion Lyophilic colloidsSystems containing colloidal particles that interact to an appreiable extent with the dispersion medium are referred to as lyophilic(solvent-loving)colloids.hydrophilic sols: gelatin, acacia, i

5、nsulin, albuminLipophilic colloids: rubber, polystyrene.A material that forms a lyophilic colloidal system in one liquid(e.g. water) may not do so in another liquid(e.g. benzene).Lyophilic colloidsSystems cont物理药剂学-课件物理药剂学-课件Lyophobic colloidsLyophobic colloids is composed of materials that have lit

6、tle attraction.e.g. gold, silver, sulfur, arsenous sulfide, and silver iodide.Lyophobic colloidsLyophobic coThe methods to prepare lyophobic colloids Dispersion methods 1,grinding method 2,sonication dispersion method 3,arc discharge methodCondensation methods 1,physical methods 2,chemical methodsTh

7、e methods to prepare lyophobgrinding methodgrinding methodsonication dispersion methodsonication dispersion methodarc discharge methodOwing to the intense heat generated by the arc, some of the metal of the electrodes is dispersed as vapor, which condenses to form colloidal particles.arc discharge m

8、ethodOwing to Physical condensation methods1,replacement of solventPhysical condensation methodsPhysical condensation methods2, Steam quench methodPhysical condensation methods2chemical condensation methods 2H3AsO3（w）+ 3H2S As2S3（sol）+6H2OFeCl3 （w）+3H2O （H） Fe(OH)3 （sol）+3HCl2H2S(w）+ SO2(g) 2H2O +3S

9、 (sol） Na2S2O3 +2HCl 2NaCl +H2O +SO2 +S (sol)2HAuCl4+ 3HCHO +11KOH 2Au(sol）+3HCOOK + 8KCl + 8H2O chemical condensation methods Sol purification1,dialysis method2,ultrafiltrationSol purification1,dialysis metdialysis methodSemipermeable membranedialysis methodSemipermeable dialysis methodElectrodialy

10、sisdialysis methodElectrodialysisultrafiltrationSemipermeable membraneultrafiltrationSemipermeable ultrafiltrationElectro ultrafiltrationultrafiltrationElectro ultrafiAssociation colloidsAssociation colloidsCMCthe critical micelle concentration (CMC) is defined as the concentration of surfactants ab

11、ove which micelles form and all additional surfactants added to the system go to micelles.CMCthe critical micelle concenType of micelleCylindrical micelleBilayerBilayer vesicleInverted micelleMicrotubuleType of micelleCylindrical miClassification and typical examples of association colloidsExampleTy

12、pe Compound Amphiphile Gegenions Anionic Sodium lauryl sulfateCH3(CH2)11OSO3-Na+Cationic Cetyl trimethyl-ammonium bromideCH3(CH2)15N+(CH3)3Br-Nonionic Polyoxyethylene laury etherCH3(CH2)10CH2O(CH2OCH2)23HAmpholytic Dimenthyldodecy lammonio-propane sulfonateCH3(CH2)11N+(CH3)2(CH2)3OSO2-Classification

13、 and typical exaProperties of surface-active agents showing changes that occur sharply at the CMCProperties of surface-active aPredict the CMC of the mixtureTo determine the minimum amount of surfactantPredict the CMC of the mixtureOptical properties of colloidsOptical properties of colloidsscatteri

14、ng of light Light scattering is a form of scattering in which light is the form of propagating energy which is scattered. Light scattering can be thought of as the deflection of a ray from a straight path, for example by irregularities in the propagation medium, particles, or in the interface betwee

15、n two media.scattering of light Light scatThe Faraday-Tyndall EffectWhen a strong beam of light is passed through a colloidal sol, a visible cone, resulting from the scattering of light by the colloidal particles, is formed. This is the Faraday-tyndall effect.The Faraday-Tyndall EffectWhenUltramicro

16、scopeAn ultramicroscope is a microscope with a system of illumination that allows viewing of tiny particles. When the diameter of a particle is below or near the wavelength of visible light (around 500 nanometers), the particle cannot be seen in a light microscope with the usual method of illuminati

17、on. The ultramicroscope system is based on light scattering, not light reflection.UltramicroscopeAn ultramicroscUltramicroscopeUltramicroscopeElectron microscope Electron microscope ,capable of yielding pictures of the actual particles, even those approaching molecular dimensions, is now widely used

18、 to observe the size, shape, and structure of colloidal particles.Electron microscope Electron m物理药剂学-课件Kinetic properties of colloids1,Thermally induced: Brownian movement, diffusion, osmosis.2,gravitationally induced: sedimentation3,applied externally: viscosityKinetic properties of colloidsBrowni

19、an Motionthe random movement of colloidal partoclesThe first satisfactory theoretical treatment of Brownian motion was made by Albert Einstein in 1905. Brownian Motionthe random movDiffusion Deduced by Einstein and StrokesWhere NA is Avogadros number, R is the gas constant, is the coefficient of vis

20、cosity of the surrounding medium, r is the radius of the spherical particle, T is the absolute temperature Diffusion is an entropy increasing process.Diffusion DiffusionDiffusionOsmotic pressureOsmotic pressureSedimentation In a gravitational field, heavy particles settle towards the foot of a colum

21、n of solution by the process called sedimentation.When a solution is allowed to stand, a state of equilibrium is finally reached when sedimentation and diffusion balance each other, that is, when in a given interval of time the amount of material which falls in the downward direction through a unit

22、area is the same as that which diffuses upward because of the greater concentration at the lower level. sedimentationdiffusionSedimentation In a gravitation物理药剂学-课件ultracentrifugationSedimentation is normally very slow, but it can be accelerated by ultracentrifugation, a technique that replaces the

23、gravitational field with a centrifugal field.Where R is the gas constant, S is the sedimentation coefficient, the unit Svedberg is 1 X 10-13 second, T is the absolute temperature, D is the diffusion constant, v is the volume of 1 g of particle, is the density of medium. ultracentrifugationSedimentat

24、isupercentrifugesupercentrifugeViscosity Viscosity is en expression of the resistance to flow of a system under an applied stress. The more greater is the applied force required to make it flow at a particular rate.Viscosity Viscosity is en exprElectrical Properties of ColloidsElectrical Properties

25、of ColloElectrokinetic PhenomenaElectrophoresisElectroosmosisSedimentation potentialStreaming potential Electrokinetic PhenomenaElectrElectrophoresisElectrophoresisElectroosmosisElectroosmosisSedimentation potentialSedimentation potentialStreaming potentialStreaming potentialStability of Colloid Sys

26、temsKinetic stability stableThermodinamic stability Lyophobic colloids unstable Lyophilic colloids stable Association colloids Stability of Colloid SystemsKiDLVO theoryEnergy（+）（-）Repulsion , VRComposite , VTPotential barrierInterparticle distancePrimary minimum(atrraction)Atrractive ,VASecondary mi

27、nimum(atrraction)DLVO theoryEnergy（+）（-）RepulsiSensitization and Protective Colloidal ActionThe presence and magnitude, or absence, of a charge on a colloidal particle is an important factor in the stability of colloidal systems.Sensitization: the addition of a small amount of hydrophilic or hydroph

28、obic colloid to a hydrophobic colloid of opposite charge tends to sensitize or even coagulate.Protection: the addition of large amounts of hydrophile, however, stabilizes the system, the hydrophile being adsorbed on the hydrophobic particles.Sensitization and Protective C Sensitization protection So

29、lubilizationAn important property of association colloids in the solution is the ability of the micelles to increase the solubility of materials that are normally insoluble, or only slightly soluble, in the dispersion medium used.SolubilizationAn important proThe surface-active agent, if taken inter

30、nally must be :1, nontoxic 2, miscible with the solvent3, compatible with the material to be solubilized4, free from disagreeable oder and taster5, relatively nonvolatileThe surface-active agent, if Association colloidsDrug Association colloidsDrug SolubilizationFactors affecting solubilization1, th

31、e chemistry of the surfactants2, the location of the drug in the micells 3, pH ( nonionic surfactants)SolubilizationFactors affectinTween 20Peppermint oilWater 010010001000505050Increasing quantity of waterTween 20Peppermint oilWater 01物理药剂学-课件物理药剂学-课件Pharmaceutical application of colloidsPharmaceutical application of Pharmaceutical application of colloidsHydrogelsPharmaceutical application of HydrogelsHydrogelsHydrogelsHydrogelsHydro