Surface modification of polydimethylsiloxane microfluidic chips by polyamidoamine dendrimers for amino acid separation

In order to improve the hydrophilicity of polydimethylsiloxane (PDMS) microfluidic chips, a series of polyamidoamine (PAMAM) dendrimers were grafted onto the PDMS pretreated by oxygen plasma and silanized with γ-glycidoxypropyltrimethoxysilane (γ-GPS). Fourier transformed infrared absorption by total attenuated reflection (ATR-FTIR) and scanning electronic microscopy (SEM) showed that PAMAM dendrimers had been grafted on the PDMS surface and a dense and uniform coating was generated. The contact angle decreased from 108.1° to 31.8° compared with the unmodified PDMS, which indicated that the hydrophilicity of PDMS improved markedly. In the modified PDMS microfluidic chips, the EOF reduced obviously and the nonspecific adsorption between the amino acids and the microchannel surface was prevented effectively. The separation efficiency of arginine and phenylalanine were as high as 7.34 × 10 4 plates/m and 8.61 × 10 4 plates/m, respectively, and the resolution ( R S ) was 4.41. Furthermore, the reproducibility of modified chips was also very excellent, which suggested they had good stability and long service life. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43580.