Using beta-lactamase to trigger supramolecular hydrogelation.
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Biomedical subjects
Publications and source records attributed to Qigang Wang.
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Hemoglobin (Hb) was intercalated at the galleries of layered niobate HCa(2)Nb(3)O(10) (HCNO). Two different kinds of layered phases of Hb-CNO composites Hb-CNO-1 and Hb-CNO-2 were obtained with the interlayer distances of 7.2 and 10.3nm in correspondence with the monolayer and bilayer arrangements of proteins between the niobate layers, respectively, based on the powder XRD pattern, HRTEM, UV-vis spectra and CHN analyses. FTIR spectra of Hb-CNO composites show that amide I and amide II bands were actually the same as those of the native Hb, which indicates that there is almost no structural change after immobilization. Michaelis-Menten model methods were used to study the peroxidatic activity of the reaction of 2-methoxyphenol and H(2)O(2) for the entrapped Hb in the galleries of HCNO. Compared to that of free Hb, the kinetic parameters of Hb-CNO k(cat), K(M) and k(cat)/K(M) were affected by the immobilization process. The immobilized Hb showed a higher relative activity than that of free Hb after incubated in phosphate buffer (pH = 7) at 80 degrees C for a period of time. The environments between the layers of HCNO are hydrophilic which will bind water tightly and help to stabilize the 'essential water' layer around the protein. So, immobilization of Hb between the layers of HCNO enhanced the activity of Hb in water-DMSO mixture.
A simple layered titanate immobilization can significantly enhance the Hb catalytic activity in organic media relative to native Hb, especially in hydrophilic dioxane systems, where the composites have an about 100 times enhancement. The interlayer water should be responsible for the increased nonaqueous catalytic activities of the immobilized Hb due to its strengthened resistance to the distorting of the Hb surface essential water layer by organic solvents.
The exfoliated single-layer titanate can rapidly restack and reversibly release heme protein simply by adjustment of the pH value. The composites have regularly layered structure and powdery morphology by their ideal layer-to-layer assembly, which provides the titanate nanosheet an unusual specific intercalation capacity of 5900 mg g(-1) for the protein. The bound and released proteins keep active relative to the intact protein. The hemoglobin thermal and organic solvent stabilities are improved by the protective environment of the titanate host.