新型固定化方法－－环氧胺树脂及硅树脂生物包埋

在生物包埋技术的研究过程中，人们发现生物功能可以融合并保存于聚合物基 质中，继溶胶凝胶生物包埋法以后，目前以发展了许多非溶胶凝胶聚合物用于蛋白 质的固定化，此类聚合物包括环氧胺树脂，硅树脂，聚乙烯塑料和聚氨酯泡沫材料 等。迄今为止，人们已成功地将多种酶包埋其中，加上原有的溶胶凝胶包埋物。这 些生物复合体为生物物质的固定化及在生物传感器和生物催化剂中的应用提供了一 个强有力的工具，此外，作为具有生物活性且防污染的聚合物，它们还有望应用于 环境，食品以及医药行业，尽管尚处于发展阶段，但是这些生物复合体将为高效生 物固定化提供一种新的手段，将具体介绍其中最受关注的环氧胺树脂和硅树脂。     

Autoinducer Sensing Microarrays by Reporter Bacteria Encapsulated in Hybrid Supramolecular‐Polysaccharide Hydrogels

A generally applicable strategy to obtain mechanically robust hydrogels for the incorporation and containment of functional reporter bacteria for the microarray and microparticle‐based detection and signaling of N‐acyl homoserine lactone autoinducers (3OC₁₂HSL) at relevant concentrations is reported. For reinforcing hydrogels of 1,4‐bi(phenylalanine‐diglycol)‐benzene (PDB), a hybrid hydrogel is formed by the combination of PDB self‐assembly with Ca²⁺ mediated alginate crosslinking. The different assembly mechanisms are shown not to interfere with each other and despite the more than four‐fold increased moduli of the hydrogels, diffusion of autoinducers into the gels remains efficient and Escherichia coli pLuxR‐green fluorescent protein (GFP) reporter bacteria are proliferating. Templating affords reporter bacteria‐loaded hydrogels with controllable shape and size. Upon exposure to 3OC₁₂HSL, the embedded bacteria exhibit an up to 12 ± 3 times increase in fluorescence intensity due to autoinducer‐triggered GFP expression. This approach can serve as a potentially generally applicable strategy to sensitively detect bacteria via their secreted autoinducers.     

Encapsulation of Viable Aerobic Microorganisms in Silica Gels

The aim of this study was to develop techniques to sterilise the surface of silica gels containing encapsulated cells and the liquid broth they were immersed in, so that the observed metabolic activities could be unambiguously assigned to fully encapsulated cells. Gel surfaces were sterilised by UV-irradiation daily. The surfaces of the gels and the overlaying medium remained sterile for 20 days following irradiation, as demonstrated by the lack of visible surface growth and viable cells in the medium. We report the encapsulation of a viable, metabolically active, aerobic fungus Penicillium chrysogenum, and the aerobic Gram-positive bacterium Streptomyces rimosus in gels derived from aqueous silica sols. Carbohydrate consumption (catabolism) and antibiotic biosynthesis (penicillin or oxytetracycline) (anabolism) were monitored in both cultures, demonstrating that the encapsulated cells remained viable within the gel matrix. This demonstrates that the silica gels are sufficiently porous to sustain metabolic activities of aerobic cells, which require the diffusion of oxygen and other substrates within the gels nanopore network.     

Denaturation and Leaching Study of Horseradish Peroxidase Encapsulated in Sol-Gel Matrices

Sol-gel matrices have been shown to be relatively inert while preserving the spectroscopic properties and biological activity of the encapsulated proteins. Horseradish peroxidase (HRP) is a hemeprotein widely used in the field of biosensors because of its high specificity for hydrogen peroxide. However, partial inactivation of the protein has been reported when incorporated in aged gels. Whether that inactivation comes from the unfolding of some of the encapsulated proteins or from the leaching of the heme non-covalent active site of HRP is evaluated by absorption and fluorescence spectroscopy. This study shows that the single Trytophan (Trp) fluorescence of HRP may be used to distinguish denaturation processes from leaching of the heme group, as well as to estimate the extent of the denaturation.