Peptides are important endogenous compounds playing critical roles in living systems. Active peptide drugs, vaccines and probes are mainly obtained from solid phase peptide synthesis (SPPS) and high throughput peptide screening (HTPS). However, there are several inherent disadvantages of traditional SPPS and HTPS such as long periods, excessive reagents consumption and expensive apparatus. Microfluidic chips represent a revolution in laboratory experimentation and bring the benefits of miniaturization, automation and integration to many research fields.

Herein, microfluidic chip based peptide synthesis, screening and identification were performed. First, an integrated continuous-flow arrayed SPPS microfluidic chip system was constructed ^[1].The microfluidic system was composed of a glass-based radial reaction chip, a diffluent chip, amino acid feeding reservoirs and continuous-flow reagent pathways. Cross-linked, porous and high-loading polystyrene beads were prepared for microfluidic SPPS. Additionally, solvent-resistant perfluoroalkoxy (PFA) was used to construct chip-sized devices featuring multiple pneumatic microvalves ^[2]. Using these micro devices, model peptides were automatically synthesized and cleaved in situ in a continuous-flow manner. The total coupling and cleavage time was significantly reduced compared to conventional bulk reactors.

Screening for peptides with high specificity and high affinity against specific targets has significant applications. In our work, firstly, one novel type of integrated tetra-layer microfluidic system for affinity peptide screening was achieved ^[3].Eccentric diffluent layers were invented for the vertical sample delivery, which eliminated the use of excessive accessories and complicated pipelines. Furthermore, for HTPS, microfluidic chip has been designed to screen peptides out from the “one bead one compound” combinatorial libraries. “Magnetic beads” were employed to enrich positive peptide beads. A microarray chip with microcavities was fabricated for high-throughput beads trapping, on-line cleavage and single bead sequencing by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Peptide screening and in-situ identification was performed with the throughput of >10³.