Peptide and peptide nucleic acid syntheses using a DNA/RNA synthesizer

Automatic In Situ Synthesis System for Polypeptide Biochip Based on Microfluidic Mixer

Biochips have become a sophisticated analytical device in the fields of biochemical sensing and genetic analysis. However, the cumbersome preparation process and the high production cost limit the versatility of its application. Herein, we have developed an automated synthesis system for in situ preparation of biochip with peptide backbone based on the microfluidic mixer and micro reaction chamber. The microfluidic mixer was used as a key component to perform the real-time activation of the carboxylic groups, leading to an instant coupling reaction of monomers with high efficiency. The repeating synthesis procedure was realized without too much manual intervention with the help of flow control system based on programmable logical controller and LabVIEW. The real-time monitoring of synthesis process was realized using a low-cost solar cell coupled with simple ultraviolet absorption device. The photodeprotection experiment revealed that an exposure time of 4 min with 20 mW/cm² ultraviolet (UV) light at 365nm was sufficient for the complete removal of 2-(2-nitrophenyl) propyloxycarbonyl (NPPOC) groups from the synthetic sites in N, N-dimethylformamide (DMF). The practical capability performance of this synthesis system was further demonstrated by the synthesis of four cycles of aminocaproic acid, and the stepwise yield of coupling was measured to be about 96%, which was comparable with the result from literature, and indicated that this system may provide a new alternative for low-cost in situ synthesis of biochip.

Solid Phase Stepwise Synthesis of Polyethylene Glycols

Polyethylene glycol (PEG) and derivatives with eight and twelve ethylene glycol units were synthesized by stepwise addition of tetraethylene glycol monomers on a polystyrene solid support. The monomer contains a tosyl group at one end and a dimethoxytrityl group at the other. The Wang resin, which contains the 4-benzyloxy benzyl alcohol function, was used as the support. The synthetic cycle consists of deprotonation, Williamson ether formation (coupling), and detritylation. Cleavage of PEGs from solid support was achieved with trifluoroacetic acid. The synthesis including monomer synthesis was entirely chromatography-free. PEG products including those with different functionalities at the two termini were obtained in high yields. The products were analyzed with ESI and MALDI-TOF MS and were found close to monodispersity.