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This paper proposes a novel handheld analyzer with disposable lab-on-a-chip technology for the electrical detection of the anesthetic propofol in human plasma samples for clinical diagnoses. The developed on-chip biosensors are based on the conduction of molecularly imprinted polymers (MIPs) that employ label-free electrical detection techniques. Propofol in total intravenous anesthesia is widely used with a target-controlled infusion system. At present, the methods employed for detecting blood propofol concentrations in hospitals comprise high-performance liquid chromatography and ion mobility spectrometry. These conventional instruments are bulky, expensive, and difficult to access. In this study, we developed a novel plastic microfluidic biochip with an on-chip anesthetic biosensor that was characterized for the rapid detection of propofol concentrations. The experimental results revealed that the response time of the developed propofol biosensors was 25 s. The specific binding of an MIP to a nonimprinted polymer (NIP) reached up to 560%. Moreover, the detection limit of the biosensors was 0.1 μg/mL, with a linear detection range of 0.1–30 μg/mL. The proposed disposable microfluidic biochip with an on-chip anesthetic biosensor using MIPs exhibited excellent performance in the separation and sensing of propofol molecules in the human plasma samples. Compared with large-scale conventional instruments, the developed microfluidic biochips with on-chip MIP biosensors present the advantages of a compact size, high selectivity, low cost, rapid response, and single-step detection.

This paper presents enhanced performance of anesthetic propofol biosensors by modifying molecularly imprinted nanocavities of biosensors. In this work, the relationship between molecularly imprinted nanocavities and performance of molecularly imprinted polymer (MIP) films is investigated. The morphological control of imprinted nanocavities on molecularly imprinted biosensors is done by adjusting polymer composition and polymerization process. The newly developed MIP biosensors are characterized using our developed microfluidic biochips and optical microsystems. Experimental results show that the sizes of molecularly imprinted nanocavities were reduced to 10 to 14 nm from 10 to 25 nm. The roughness of the MIP film surface was reduced to 2.5 nm from 6.6 nm. Smaller imprinted nanocavities have better molecular separation performance. The specificity and linearity of the anesthetic biosensors could be enhanced by adjusting morphology of imprinted nanocavities. The linearity and the sensitivity of the microfluidic biochip with an improved on-chip MIP biosensor have been enhanced from 0.9341 to 49.5 mV/mm2.ml/μg, respectively, to 0.9782 and 176.9 mV/mm2.ml/μg. The anesthetic propofol biosensor presented in this study is applicable to numerous fluidic-based disposable biochips.