Injectable polyelectrolyte complex-nascent HAP biodegradable antibiotic delivery system for the treatment of osteomyelitis

An injectable osteoconductive polyelectrolyte complex –hydroxyapatite formulation capable of controlled delivery of ciprofloxacin has been developed from a novel biodegradable polyelectrolyte complex and antibiotic loaded nascent hydroxyapatite (n-HAP) for the treatment of osteomyelitis. A single source (chitosan) derived polyelectrolytes were complexed in situ in the presence of n-HAP, pre-loaded with ciprofloxacin. The PEC- (n-HAP) nanoformulation (HPEC) was characterized by FT-IR, XRD, TGA and TEM analyses. HPEC combines functionalities of n-HAP (crystallinity and osteoconductivity) as well as PEC (biodegradable hydrophilic electrostatically bound macromolecular network) imparting better control over swelling and degradation kinetics favourable for drug release and transport of micronutrients. MTT assay and cytoskeleton staining (MG 63 cells) established cytocompatibility of HPEC. Early biomimetic mineralization of apatite was manifested under simulated physiological condition with a Ca/P of 1.23 (day 3) and 1.55 (day 6) complimented by in vitro biomineralization of MG-63 and Human Osteosarcoma (HOS) cells in a week (Alizarin Red S staining), which was further validated by calcium quantification. Antibacterial efficacy of HPEC has been evaluated by delivery kinetics of ciprofloxacin and by disc diffusion method against S. aureus and E. coli. The injectable system therefore possesses unique combination of functionalities: osteoconduction enriched with early biomineralization, antibacterial activity and is biodegradable; hence highly suitable for osteomyelitis treatment.

Recent Advances of Macromolecular Hydrogels for Enzyme Immobilization in the Food Products

Enzymes are one of the main biocatalysts with various applications in the food industry. Stabilization of enzymes on insoluble carriers is important due to the low reuse, low operational stability, and high cost in applications. The immobility and the type of carrier affect the activity of the immobile enzyme. Hydrogels are three-dimensionally cross-linked macromolecular network structures designed from various polymers. Hydrogels can provide a matrix for an immobile enzyme due to their extraordinary properties such as high water absorbing capacity, carrier of bioactive substances and enzymes, biocompatibility, safety, and biodegradability. Therefore, this study mainly focuses on some enzymes (Lactase, Lipases, Amylases, Pectinase, Protease, Glucose oxidase) that are of special importance in the food industry. These enzymes could be immobilized in the hydrogels constructed of macromolecules such as kappa-carrageenan, chitosan, arabic gum, pectin, alginate, and cellulose. At last, in the preparation of these hydrogels, different enzyme immobilization methods in macromolecular hydrogels, and effect of hydrogels on enzyme activity were discussed.

Optimizing energy harvesting performance of silicone elastomers by molecular grafting of azobenzene to the macromolecular network

Homogeneous silicone rubber was prepared for DEG applications by molecular grafting of azobenzene to the polymer network. The energy conversion efficiency of the composite was optimized to 5.01%, increased by 150% compared to the matrix.

The Poynting effect in elastomeric bars undergoing chemo-mechanical evolution

This work considers a rubber cylinder under zero axial force that elongates in response to the normal stresses produced during torsion (the Poynting effect). The combined elongation and twisting deformation occurs at an elevated temperature at which the rubber undergoes time-dependent scission and re-crosslinking of its macromolecular network junctions. A constitutive theory accounting for this microstructural change is used in an analytical and numerical study of the interaction of the deformation and the scission or re-crosslinking process. Examples show the time-dependence of elongation for several twist histories.

Imaging the Extracellular Matrix in Prevalent Cardiovascular Diseases

The extracellular matrix (ECM) is a highly complex macromolecular network present in all tissues and organs. The ECM is continuously remodelling under an orchestrated process facilitated by many matrix-degrading and matrix-synthesising enzymes in both health and disease. Disturbance of this balance can be the result of or can lead to various diseases. In cardiovascular diseases (CVDs), changes to the ECM are evident in conditions including: atherosclerosis, myocardial infarction (MI), venous thromboembolism (VTE) and abdominal aortic aneurysm (AAA). ECM proteins and ECM regulating enzymes are differently expressed in various CVDs. Most importantly, the altered deposition, macromolecule arrangement and activity of the ECM makes it an attractive marker of disease onset, pathogenesis and progression. Many medical imaging modalities allow disease assessment by exploiting native image contrast, by using non-targeted or by using protein or cell specific (targeted) imaging probes. However, the ability to directly visualise and quantify changes in specific ECM proteins enhances our understanding of the biological role of these proteins, enables monitoring of disease progression and response to treatment and may improve patient diagnosis and allocation of personalised therapies. This review focuses on the biochemistry of the major extracellular matrix proteins and advancements in the development of ECM-targeted probes for molecular imaging of CVD, particularly for applications of molecular magnetic resonance imaging (MRI) and position emission tomography (PET) imaging.