Polymeric miscelle
- 1. MAHARAJA AGRASEN UNIVERSITY(SCHOOL OF PHARMACY) POLYMERIC MICELLE Submitted to: Submitted by: Mr. Hans Raj Sagar Kundlas (Astt. Professor) MAU16BPH049 B. Pharmacy (6th semester) 1
- 2. • Polymeric micelles are formed from self- aggregation of amphiphilic block / graft co- polymers with the hydrophobic part of the polymer on the inside (core) and hydrophilic on the outside (shell). • In drug delivery, PM are classified under the “Nano carriers”. • A polymeric micelle usually consists of several hundred block copolymers and has a diameter of about 20-50 nm INTRODUCTION 2
- 4. • Self-assembled supramolecular core-shell structure. • Core is a dense region consisting of the hydrophobic part of the amphiphilic polymer. • Core serves as a reservoir for drugs with low aqueous solubility. • Shell consisting hydrophilic portion of the co-polymer. • The morphology of micelles is the hydrophilic–hydrophobic balance of the block copolymer defined by the hydrophilic volume fraction, f.( f>45% form PM) 4
- 5. MECHANISM OF MICELLIZATION Amphiphilic block or graft copolymers behave in the same manner as that of conventional amphiphiles and in aqueous solution, above CMC, it forms PM. CMC (critical micelle concentration) it is the minimum concentration required by amphiphilic molecule to start micellization . CMT( critical micelle temperature) The temperature below which amphiphilic molecules exist as unimers and above which as aggregates. Aggregation number is the number of molecules present at CMC. They form spherical structure in order to reduce the free energy of system. 5
- 6. TYPES OF POLYMERIC MICELLE • On the basis of the type of intermolecular forces governing the segregation of the core segment from the aqueous Environment, those formed by ; 1. Hydrophobic interaction – these are Conventional micelles 2. Electrostatic interaction – these are Polyion complex micelle 3. Metal complexation – these are Noncovalently Connected Polymeric Micelles . 6
- 7. METHOD OF PREPARATION Can be prepared mainly by three common approach: Direct dissolution Solvent casting technique Dialysis 7
- 8. CONTINUED: Direct dissolution Direct dissolution of drug and copolymer in water It is simple technique Drug loading efficiency is low Solvent casting Volatile organic solvent used to dissolve the copolymer & drug After complete evaporation of solvent there is thin film obtained Drug loaded micelles are obtained by reconstitution of film in water 8
- 9. • Dialysis • Solution of drug and copolymer in organic solvent are placed in dialysis bag and the solvent is exchanged with water by immersing the bag into water inducing micelle assembly. • This method is suitable for loading of drug which has poor solubility • Suitable for core forming blocks are long & more hydrophobic • Dialysis process often take mare than 36 hours for efficient drug loading • Lyophilization method • Water tert. Butanol mixt. Is used for dissolving drug as well as polymer and then solution is polymerised • Drug loaded polymeric micelles obtained by redispersing the lyophilized product in suitable vehicle • It is simple and cost effective method 9
- 10. CHARACTERIZATION OF POLYMERIC MICELLES CMC: It is the key parameter in the formation & the static stability of polymeric micelles Con. of amphiphilic polmer in aqueous media if , >cmc – exhist in t5he form of polymeric micelles if , < cmc – micelles may collapse 10
- 11. CONTI. • CMC determination • Surface tension measurement • Chromatography • Light scattering • DSC • Viscometry • Pyren as fluorscent probe • Size & shape (geometry) • The polydispersity index of prepared structure is • obtained by examining the micellar solution using • light scattering techniques 11
- 12. CONTI. Monodisperse micelles If produce blue color indicate good micellar preparation If produce white color indicate aggregation Scanning electron microcopy & transmission electronmicroscopy has been used for size and shape determination In-vitro drug release behavior 12
- 13. • Solubilization • Solubilization process leads to enhance solubility of water insoluble molecule in water • Non-osized polymeric micelles elevate GI uptake & enhance its bioavailability • Targetting delivery of drug • It is usually achieved by one of the following approaches • Permeability enhancer • Retention effect • Stimuli sensitivity • internal : pH, enzymes • external : temp. ,light, ultrasound, magnetic field • Liganding to micelle surface • Immunomicelles APPLICATIONS 13
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