Arginine-Glycine-Aspartate (RGD) tripeptide can promote cell adhesion when present in the amino acid of proteins such as fibronectin. In order to demonstrate the bioactivity of an RGD-containing silk protein, a gene encoding the RGD motif-containing peptide GSGAGGRGDGGYGSGSS (–RGD–) derived from nonmulberry silk was designed and cloned, then multimerised and inserted into a commercial pGEX expression vector for recombinant expression of (–RGD–)n peptides. Herein, we focus on two glutathione-S-transferase (GST)-tagged fusion proteins, GST–(–RGD–)4 and GST–(–RGD–)8, which were expressed in Escherichia coli BL21, purified by GST affinity chromatography, and analyzed with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry (MS). Target peptides (–RGD–)4 and (–RGD–)8 (6.03 and 11.5 kDa) were cleaved from the GST-tag by thrombin digestion, as verified with MS and SDS-PAGE. Isoelectric point analysis confirmed that target peptides were expressed and released in accordance with the original design. Target peptides self-assembled into a mainly α-helical structure, as determined by circular dichroism spectroscopy. Furthermore, (–RGD–)4 and (–RGD–)8 modified mulberry silk fibroin films were more effective for rapid cell adhesion, spreading and proliferative activity of L929 cells than some chemically synthesized RGD peptides modified and mulberry silk lacking the RGD motif.

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Recently, the microfluidic system is one of the most trending research topics in the world due to its unique characteristics and great advantages. The present mini-review deals with the application of micro total analysis system for the biomedical fields, such as in situ detection, enrichment, imaging, and quantification of biomolecules and cell. The recent progress of the microfluidic system on cancer, tumor, HIV, diabetes, malaria and tuberculosis was displayed.

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