Portable colorimetric sensors based on supported ionic liquid materials for L-asparagine detection

Abstract

L-asparaginase (ASNase) is an amidohydrolase enzyme applied in the pharmaceutical industry as an anticancer agent in the treatment of lymphoproliferative disorders. ASNase is also used in biosensors for the detection of L-asparagine in blood serum samples of acute lymphoblastic leukemia (ALL) patients. However, the high cost of non-portable and sensitive L-asparagine detection techniques, being mainly carried out by chromatography, reinforces the need of developing portable and low-cost colorimetric sensors for L-asparagine detection. Supported ionic liquid (SIL) materials comprise ionic liquids (ILs) covalently attached to the support, enabling distinct interactions to be established among the target compounds and the support. SIL materials with quaternary ammonium cations and Clˉ as the counterion have been successfully applied in the immobilization of ASNase. In this work, SIL materials based on silica fabric functionalized with quaternary ammonium cations and the Cl− anion, viz. silica fabric functionalized with dimethylbutylpropylammonium chloride ([SF][N3114]Cl) and silica fabric functionalized with triethylpropylammonium chloride ([SF][N3222]Cl), were synthesized, characterized through several distinct techniques. These novel materials were also investigated as portable colorimetric sensors for L-asparagine detection in aqueous samples, i.e., aqueous solution of L-asparagine or commercial blood serum spiked with different L- asparagine concentration levels (10-1 M – 10-5 M). The developed low-cost and portable silica fabric SILs allows the fast and accurate detection of L-asparagine at different concentration levels.