Novel dense CO2 technique for beta-galactosidase immobilization in polystyrene microchannels

Stabilization of β-Galactosidase on Modified Gold Nanoparticles: A Preliminary Biochemical Study to Obtain Lactose-Free Dairy Products for Lactose-Intolerant Individuals

The unique chemical, optical, and electrical characteristics of nanoparticles make their utilization highly successful in every field of biological sciences as compared to their bulk counterpart. These properties arise as a result of their miniature size, which provides them an excellent surface area-to-volume ratio, inner structure, and shape, and hence increases their surface characteristics. Therefore, this study was undertaken to engineer gold nanoparticles (AuNPs) for improving their catalytic activity and stability in biotechnological processes. The characterization of AuNPs was performed by XRD, UV spectra, and TEM. The synthesized AuNPs were surface-modified by polyvinyl alcohol (PVA) for binding the enzyme in excellent yield. The developed immobilized enzyme system (PVA-AuNPs-β-galactosidase) displayed pH optima at pH 7.0 and temperature optima at 40 °C. Moreover, the stability of PVA-AuNPs-β-galactosidase was significantly enhanced at wider pH and temperature ranges and at higher galactose concentrations, in contrast to the free enzyme. β-galactosidase bound to PVA-modified AuNPs exhibited greater operational activity, even after its sixth reuse. The developed nanosystem may prove useful in producing lactose-free dairy products for lactose-intolerant patients.

Controlling the porosity and microarchitecture of hydrogels for tissue engineering

Tissue engineering holds great promise for regeneration and repair of diseased tissues, making the development of tissue engineering scaffolds a topic of great interest in biomedical research. Because of their biocompatibility and similarities to native extracellular matrix, hydrogels have emerged as leading candidates for engineered tissue scaffolds. However, precise control of hydrogel properties, such as porosity, remains a challenge. Traditional techniques for creating bulk porosity in polymers have demonstrated success in hydrogels for tissue engineering; however, often the conditions are incompatible with direct cell encapsulation. Emerging technologies have demonstrated the ability to control porosity and the microarchitectural features in hydrogels, creating engineered tissues with structure and function similar to native tissues. In this review, we explore the various technologies for controlling the porosity and microarchitecture within hydrogels, and demonstrate successful applications of combining these techniques.

The development of a dense gas solvent exchange process for the impregnation of pharmaceuticals into porous chitosan

The aim of this study was to prepare stable formulations of poorly water-soluble drugs in amorphous forms to enhance their dissolution rates, promote the bioavailability, minimize the dosage, thereby theoretically decreasing their side effects. A dense gas solvent exchange process was developed for the impregnation of poorly water-soluble drugs such as camptothecin and griseofulvin into a chitosan matrix. The amount of drug impregnated was measured by UV-spectrophotometery and gravimetric techniques. Pore characteristics and the crystallinity of the drugs in the impregnated chitosan were measured. Homogenous nano-sized pores with thin walls were formed in chitosan using the dense gas solvent exchange process. The method was efficient for the impregnation of a drug into chitosan. Results of XRD, Fourier transform infrared spectroscopy and differential scanning calorimetry demonstrated that as a result of interaction between chitosan and the drug, both camptothecin and griseofulvin were in amorphous forms after processing. The dissolution rate of processed griseofulvin was increased threefold due to the hydrophilic properties of chitosan and its interaction with the drug. A new approach was developed for promoting drug bioavailability that has the potential to decrease the required dose and side effects, particularly for chemotherapeutic drugs with narrow therapeutic index.

Density functional approach for modeling CO2 pressurized polymer thin films in equilibrium

We have used polymer density functional theory to analyze the equilibrium density profiles and interfacial properties of thin films of polymer in the presence of CO(2). Surface tension, surface excess adsorption of CO(2) on polymer surface, and width of the interface are discussed. We have shown the changes in these properties in the presence of CO(2) and with increasing film thickness and their inverse linear relationship with increasing chain length. One of our important findings is the evidence of segregation of end segments toward the interface. We have introduced a new method of representing this phenomenon by means of Delta profiles that show increase in segregation owing to the presence of CO(2) and with increasing chain length. We also make predictions for the octacosane-CO(2) binary system near the critical point of CO(2). Our results indicate qualitative trends that are comparable to the similar experimental and simulation studies.