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Enzymatic catalysis in microreactors has attracted growing scientific interest because of high specific surface enabling heat and mass transfer and easier control of reaction parameters in microreactors. However, two major challenges that limit their application are fast inactivation and the inability to the biocatalysts in microchannel reactors. A fluid and unsinkable immobilized enzyme were firstly applied in a microchannel reactor for biocatalysis in this study. Functionalized forms of graphene-immobilized naringinase flowing in microchannels have yielded excellent results for isoquercitrin production. A maximum yield of 92.24 ± 3.26% was obtained after 20 min in a microchannel reactor. Ten cycles of enzymatic hydrolysis reaction were successively completed and an enzyme activity above 85.51 ± 2.76% was maintained. The kinetic parameter V m/K m increased to 1.9-fold and reaction time was decreased to 1/3 compared with that in a batch reactor. These results indicated that the moving and unsinkable graphene sheets immobilized enzyme with a high persistent specificity and a mild catalytic characteristic enabled the repetitive use of enzyme and significant cost saving for the application of enzyme catalysis. Thus, the developed method has provided an efficient and simple approach for the productive and repeatable microfluidic biocatalysis.

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The exploration of safe and efficient polycationic gene vectors from natural small molecules such as kanamycin was proposed. Cationic hyperbranched glycoconjugated polymer was synthesized by the Michael-addition polymerization of kanamycin and N,N 0 -methylenebisacrylamide, and the resultant product was well characterized by FTIR, 1 H NMR, 13 C NMR, SEC-MALLS and z-potential analyses. The nitrogen content (7.3%) of this kanamycin-based hyperbranched glycoconjugated polymer was much lower than that (32.6%) of polyethylenimine (PEI) control. Moreover, this resultant polymer could be degraded in acidic conditions. Therefore, the hyperbranched glycoconjugated polymer showed low cytotoxicity, even lower than that of natural biomacromolecule chitosan. Due to the existence of various primary, secondary and tertiary amines in the polymer backbone, hyperbranched glycoconjugated polymer exhibited high buffering capacity and strong pDNA condensation ability. In vitro transfection showed that the luciferase expression of hyperbranched glycoconjugated polymer was about 4.4 Â 10 8 RLU per mg protein, approximately 33-fold greater than that of chitosan transfection. These results demonstrate that the construction of highly branched polycations from natural small molecules provides a new opportunity for developing safe and efficient gene vectors.