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Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.

Electrospun fiber matrices composed of scaffolds of varying fiber diameters were investigated for potential application of severe skin loss. Few systematic studies have been performed to examine the effect of varying fiber diameter electrospun fiber matrices for skin regeneration. The present study reports the fabrication of poly[lactic acid-co-glycolic acid] (PLAGA) matrices with fiber diameters of 150-225, 200-300, 250-467, 500-900, 600-1200, 2500-3000 and 3250-6000 nm via electrospinning. All fiber matrices found to have a tensile modulus from 39.23 ± 8.15 to 79.21 ± 13.71 MPa which falls in the range for normal human skin. Further, the porous fiber matrices have porosity between 38-60 % and average pore diameters between 10-14µm. We evaluated the efficacy of these biodegradable fiber matrices as skin substitutes by seeding them with human skin fibroblasts (hSF). Human skin fibroblasts acquired a well spread morphology and showed significant progressive growth on fiber matrices in the 350-1100 nm diameter range. Collagen type III gene expression was significantly up-regulated in hSF seeded on matrices with fiber diameters in the range of 350-1100 nm. Based on the need, the proposed fiber skin substitutes can be successfully fabricated and optimized for skin fibroblast attachment and growth.

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Abstract1. Curcumin is a naturally occurring poly-phenolic compound with a broad range of favorable biological functions including anti-cancer, anti-oxidant and anti-inflammatory activities. The low bioavailability and in vivo stability of curcumin require the development of suitable carrier vehicles to deliver the molecule in a sustained manner at therapeutic levels.2. We investigated the feasibility and potential of poly(caprolactone) (PCL) nanofibers as a delivery vehicle for curcumin for wound healing applications. By optimizing the electrospinning parameters, bead-free curcumin loaded PCL nanofibers were developed.3. The fibers showed sustained release of curcumin for 72 h and could be made to deliver a dosage much lower than the reported cytotoxic concentration while remaining bioactive. Human foreskin fibroblast cells (HFF-1) showed more than 70% viability on curcumin loaded nanofibers. The antioxidant activity of curcumin loaded nanofibers was demonstrated using an ORAC assay and by the ability of the fibers to maintain the viability of HFF-1 cells on the fibers under a condition of oxidative stress. The curcumin loaded nanofibers also reduced inflammatory induction as evidenced by low levels of IL-6 release from mouse monocyte-macrophages seeded on the fibers following stimulation by E.coli-derived lipopolysaccharide (LPS). The in vivo wound healing capability of the curcumin loaded PCL nanofibers was demonstrated by an increased rate of wound closure in a streptozotocin (STZ) induced diabetic mice model.4. These results demonstrate that curcumin loaded PCL nanofiber matrix is bioactive and has potential as a wound dressing with antioxidant and anti-inflammatory properties.

Advancements in nanobiotechnology are revolutionizing our capability to understand biological intricacies and resolve biological and medical problems by developing subtle biomimetic techniques. Nanocomposites and nanostructured materials are believed to play a pivotal role in orthopedic research since bone itself is a typical example of a nanocomposite. This article reviews current strategies using nanobiomaterials to improve current orthopedic materials and examines their applications in bone tissue engineering. Preliminary investigations support the potential of nanobiomaterials in orthopedic applications; however, significant advancements are necessary to achieve clinical use. Overall, current trends in nanobiotechnology foreshadow a bright future through the use of nanobiomaterials in the orthopedic domain. ß

Biodegradable polyphosphazenes have been investigated for a variety of applications, such as controlled drug delivery matrixes, tissue-engineering scaffolds, membranes, and bone-type composites. In this study we have evaluated the effect of side group chemistry on the properties of biodegradable phosphazene polymers that contain ethyl alanato side groups together with ethyl glycinato, p-methylphenoxy, or p-phenylphenoxy side groups. The polymers were synthesized by a macromolecular substitution route. The molecular weights of aryloxy/amino acid ester cosubstituted polymers were much higher than the amino acid ester substituted polyphosphazenes described earlier. Polymer properties, such as glass transition temperature, hydrolytic degradation, surface wettability, tensile strength, and modulus of elasticity varied over a wide range following changes to the type of co-substituents on the polymer backbone. The glass transition temperatures varied from -10 to 35 degrees C and increased with the bulkiness of the side groups. Polymer films in phosphate buffer saline solution showed molecular weight declines ranging from 58% to >80% and mass loss ranging from 4% to 90% over a period of 7 weeks. Water contact angles for polymer films varied from 63 degrees to 107 degrees , with the highest angles for the alanine ethyl ester and p-phenylphenoxy cosubstituted polyphosphazene. The tensile strengths were in the range of 2.4-7.6 MPa and the modulus of elasticity was in the range of 31.4-455.9 MPa. Thus, in this study we have demonstrated the tunability of biodegradable polyphosphazenes to suit a range of biomedical applications.