Polymeric scaffolds play a crucial role in engineering process of new tissues and effect the cell growth and viability. PLCL copolymers are found to be very useful during cell growth due to their elastic behavior and mechanical strength. Thus, low molecular weight PLCL copolymers of various ratios viz. PLCL(90/10), PLCL(75/25), PLCL(50/50) and PCL were synthesized by ring opening polymerization using stannous octoate as a catalyst. Synthesized polymers were characterized by GPC, 1 H-NMR, FTIR and XRD. The thermal properties of the copolymers were studied using TGA and DSC. Microspheres of about 100 lm diameter were prepared for different copolymers and their in vitro degradation behaviors were studied up to 108 days. It was observed that degradation of PLA content in polymer backbone occurs faster than PCL component which is also indicated by corresponding change in ratios of PLA/PCL, as determined by 1 H-NMR. SEM images of microspheres depicted the surface morphology during degradation and suggested the faster degradation for PLCL (50:50). Copolymers of different thermal, mechanical properties and different degradation behaviors can be prepared by adjusting the composition of copolymers. Various synthesized polymers from this work have been tested in our laboratory as polymeric scaffold for soft tissue engineering.

P-15 modified poly(L-lactide-co-epsilon-caprolactone) (PLCL) microspheres were investigated as scaffolds for tissue engineering applications. PLCL copolymer was synthesized by ring opening polymerization and was composed of a soft matrix of mainly epsilon-caprolactone moieties and hard domains containing more of L-lactide units thus exhibiting a rubber like elasticity responsible for providing mechanical strength to scaffolds. Microspheres were fabricated by solvent evaporation method and surface modified with P-15, a synthetic analogue of collagen. These were then evaluated for cell adhesion, ECM formation and cell proliferation. Anchorage dependent cell lines LLCPK-1 and L6 were seeded on PLCL microspheres (unmodified surface activated microspheres) and P-15-PLCL microspheres (P-15 modified microspheres). P-15 modified microspheres showed significantly higher cell adhesion and viability than unmodified microspheres. Scanning electron microscopy also revealed copious amount of extra-cellular matrix production by P-15. Initial results of cell culture experiment on two different cell lines suggested that the growth of LLCPK-1 in a 3D environment with P-15 modified microspheres is via spreading and flattening on the surface of scaffold followed by formation of a sheet-like structure while L6 grew in the form of multilayered structures with formation of interparticulate cellular bridges. The 3D moldable nature, combined with modification of surface chemistry with cell adhesion molecules such as P-15 to enhance proliferation of epithelial cells and myoblasts, recommends further investigation of P-15-PLCL microspheres for production of an ideal scaffold for soft tissue engineering.

This study is focused on the preparation of doxorubicin-loaded nanopolymersomes (PolyDoxSome) and assessment of the effects of various solvents and process variables on the size and drug loading during preparation of formulation. PolyDoxSome was prepared by nanoprecipitation method using amphiphilic (PEG)₃-PLA copolymer, and the formation of polymersomes was assessed by dynamic light scattering and optical and transmission electron microscopy and evaluated for in vitro release profile and in vitro cytotoxicity. A systematic investigation indicated that solvent composition, order of addition, aqueous phase, copolymer concentration, and external energy input have significant influence on size and dispersity of PolyDoxSome. Under optimized conditions, PolyDoxSome had a size range of 130-180 nm with PDI < 0.2, a zeta potential ∼-8 mV, and a drug loading at ∼11% w/w with an encapsulation efficiency at ∼53% w/w. In vitro release profile of PolyDoxSome at 37 °C demonstrated that doxorubicin release was pH dependent and gave higher release at pH 5.5 in comparison to the release at pH 7.4 (similarity factor, f₂ < 50). PolyDoxSome exhibited enhanced cellular uptake of doxorubicin compared to free doxorubicin solution in MCF-7 cell line and showed a better cytotoxicity of doxorubicin at equivalent dose in nanopolymersomes. In conclusion, size and dispersity were strongly influenced by duration of magnetic stirring and overall composition of organic/aqueous media; however, size and dispersity were retained against different degrees of dilution. PolyDoxSome was able to control the release of doxorubicin in pH dependent manner and effectively deliver the drug in active form to MCF-7 breast cancer cells.

In this study, porous poly(lactide-co-glycolide) (PLGA) (50/50) microspheres have been fabricated by the gas-foaming technique using ammonium bicarbonate as a gas-foaming agent. Microspheres of different porosities have been formulated by varying the concentration of the gas-foaming agent (0%, 5%, 10% and 15% w/v). These microspheres were characterized for particle size, porosity and average pore size, morphology, water uptake ratio and surface area and it was found that the porosity, pore size and surface area increased on increasing the concentration of the gas-foaming agent. Further, the effect of porosity on degradation behavior was evaluated over a 12 week period by measuring changes in mass, pH, molecular weight and morphology. Porosity was found to have an inverse relationship with degradation rate. To render the surface of the microspheres biomimetic, peptide P-15 was coupled to the surface of these microspheres. In vitro cell viability, proliferation and morphological evaluation were carried out on these microsphere scaffolds using MG-63 cell line to study the effect of the porosity and pore size of scaffolds and to evaluate the effect of P-15 on cell growth on porous scaffolds. MTT assay, actin, alizarin staining and SEM revealed the potential of biomimetic porous PLGA (50/50) microspheres as scaffolds for tissue engineering. As shown in graphical representation, an attempt has been made to correlate the cell behavior on the scaffolds (growth, proliferation and cell death) with the concurrent degradation of the porous microsphere scaffold as a function of time.

This injectable, biocompatible and bioactive in situ hardening composite graft was found to be suitable for load-bearing bone regeneration applications using minimally invasive surgery.