Polycaprolactone(PCL)

POLYCAPROLACTONE (PCL)

1. POLYCAPROLACTONE (PCL) Rajeshwar kr. yadav M.Pharm (1 st Year) Dept. of Pharmacology 1

2. 2 CONTENTS: General description Introduction Synthesis 4. Biodegradation Pharmaceutical applications Other applications Recent advancements Advantages and disadvantages 9. References

3. 1. GENERAL DESCRIPTION : Biodegradable polymer Non-toxic Biodegradable in soil Broad miscibility Mechanical compatibility with many polymers and good adhesion to a broad spectrum of substrates. IUPAC name : (1,7)-Polyoxepan-2-one Systematic IUPAC name: Poly(hexano-6-lactone) Other names : 2-Oxepanone homo polymer 6-Caprolactone polymer Melting point : 60 °C (140 °F) Density : 1.071 g/ml Chemical formulae : (C 6 H 10 O 2 ) n Molecular weight: 3000-80,000 g/mol 3

4. 2. INTRODUCTION: Polycaprolactone (PCL) is a polymer composed of hexanoate repeat units, included in the class of aliphatic polyesters. PCL has been thoroughly investigated for its peculiar mechanical properties, miscibility with a large range of other polymers, and biodegradability. The physical, thermal, and mechanical properties of PCL mainly depend upon its molecular weight and degree of crystallinity . PCL is strongly hydrophobic, semicrystalline , highly soluble at room temperature. Easily processable due to the low melting temperature and exceptional blend compatibility. 4

5. PCL has been extensively studied for the preparation of controlled drug delivery systems. Its permeability to a wide range of drugs enabled uniform drug distribution in the matrix, assuring along-term release up to several months by a degradation mechanism. PCL has been largely used for the preparation of long-term implants and scaffolds . PCL has also been certified as FDA approved (Food and Drug Administration, USA) and CE registered mark (European Community) 5

6. 3. SYNTHESIS: The first synthesis of PCL by thermal treatment of 𝜀- caprolactone was reported by Van Natta and co-workers. PCL is still mainly synthesized by ionic and metal catalyzed ring-opening polymerization (ROP) of the cyclic monomer 𝜀 – caprolactone . The radical ring opening polymerization (RROP) of 2-methylene-1,3-dioxepane (MDO), using different conditions, and on the condensation of 6-hydroxycaproic acid 6 Stannous octonoate

7. The poly condensation of 6-hydroxycaproic acid, this synthetic route is also reported. The most interesting approaches are based on the enzymatic synthesis, such as those based on the use of lipase . The use of Candida Antarctica Lipase B (CALB) immobilized on acrylic resin slowly gives rise to PCL with an average degree of polymerization. 7

8. 4. BIODEGREDATION: PCL is degraded by hydrolysis of its ester linkages in physiological conditions (such as in the human body) PCL undergoes a two-stage degradation process : The non enzymatic hydrolytic cleavage of ester groups. When the polymer is more highly crystalline and has a low molecular weight (less than 3000) the polymer is shown to undergo intracellular degradation. Degradation is started by the hydrolysis of polymer chain 6-hydroxyhexanoic acid to acetyl co enzyme A which goes further degradation in TCA. 8

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10. 5. PHARMACEUTICAL APPLICATIONS: PCL is suitable for controlled drug delivery due to a high permeability to many drugs Biodegradation of PCL is slow in comparison to other polymers, so it is more suitable for long-term delivery. PCL also has the ability to form compatible blends with other polymers which can affect the degradation kinetics. 10

11. 11 Several drug delivery vehicles composed of PCL, such as microspheres, microcapsules, nano spheres and micro and nano fibers have been developed for the controlled release of drugs or protein.

12. 6. OTHER APPLICATIONS: PCL loaded with antibiotics may be used to treat infections of the respiratory tract, like tuberculosis. Investigations were carried out based upon phenotypic responses of human bone marrow mesenchymal cells . PCL/biomedical ceramic materials have been studied for possible osteo tissue regeneration. Action of PCL/graded insulin/beta-5 glycerophosphate concentrations on osteochondral tissue formation. Other general uses include: extrusion aid, die lubricant, mold release, pigment and filler dispersion aid and polyester segments in urethanes and block polyesters. 12

13. 7 . RECENT ADVANCEMENTS: PCL attracted interest for the design of green materials/biomaterials used for various applications. PCL mechanical properties make it suitable for medical applications complementary to tissue engineering, such as, for example, wound dressing, contraceptive, and dentistry but also in non medical fields such as environment, packaging and food. 13

14. 8. ADVANTAGES AND DISADVANTAGES: 14

15. 15 9. REFERENCES: 1. Bikiaris D N, Papageorgiou G Z, Achilias D S, Pavlidou E and Stergiou A. "Miscibility and enzymatic degradation studies of poly(e- caprolactone )/poly(propylene succinate ) blends". European Polymer Journal, Vol 43, 2007, pp. 2491–2503. 2. Johnson J, Niehaus A, Nichols S, Lee D, Koepsel J, Anderson D and Lannutti J, " Electrospun PCL in vitro: a microstructural basis for mechanical property changes". J. Biomater . Sci. Polymer Edn , Vol 20, 2009, pp. 467–481.

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