Abstract
Composites of tetracycline (Tc)-imprinted polymethacrylates and quantum dots have been coated on chemically pretreated polyimide substrates (PIs) as fluorescent sensors. In this study, PIs were pretreated by capacitively coupled plasma (CCP) before coating the same composites on them. For the first time, to fabricate sensors by plasma modification of PIs, the CCP conditions, including plasma gas, flow rate, radio frequency generation power, and duration time, the fabrication details, including coating, baking, and stripping steps, and the sample loading process were optimized to perform a linear decrease in fluorescent intensity with Tc concentrations in the range of 5.0–3000 μM (R2 = 0.9995) with a limit of detection of 0.2 μM (S/N = 3, relative standard deviation (RSD) = 2.2%). The selectivity of the stripped PIs was evaluated by the imprinting factors (IFs) for Tc (IF = 7.2), other Tc analogues (IF = 3.4–5.3), and steroids (IF ≈ 1) and by the recoveries of 5.0 μM Tc from bovine serum albumin at 300 μg∙mL−1 (98%, RSD = 3.2%), fetal bovine serum at 1.5 ppt (98%, RSD = 2.8%), and liquid milk (94.5%, RSD = 5.3%). The superiority of the present plasma-treated-based sensor over the previous chemically-treated one in fabrication efficiency and detection effectiveness was clear.
Highlights
Plastic substrates have been successfully used in electrochemical sensors with advanced sensing materials and fabrication techniques, such as substrate pretreatment, film deposition, line patterning, and module assembly, at low temperatures that a plastic substrate can sustain [1,2,3].Many electrochemical sensors are electronic noses, which aim at gas detection to avert false conductive connections between the sensing elements in solution
To the best of our knowledge, sensors fabricated with dry modification of polyimide substrates (PIs) have not been described to date, chemical modification of PIs has been used as a substrate for bonding quantum dots (QDs) as fluorescent sensors in our previous study [21]
The pristine PI substrates do not adhere to the molecularly imprinted polymers (MIPs)-QD composites
Summary
Plastic substrates have been successfully used in electrochemical sensors with advanced sensing materials and fabrication techniques, such as substrate pretreatment, film deposition, line patterning, and module assembly, at low temperatures that a plastic substrate can sustain [1,2,3]. To the best of our knowledge, sensors fabricated with dry modification of PIs have not been described to date, chemical modification of PIs has been used as a substrate for bonding quantum dots (QDs) as fluorescent sensors in our previous study [21]. PI substrates were treated by capacitively coupled plasma and their efficiency and effectiveness in sensor fabrication and fluorescence measurement were compared with chemically treated PI [21] and glass [34] substrates as they were all coated with the same composite of tetracycline (Tc)-imprinted polymethacrylate and CdTe QD after the treatments. Other significant steps in subsequent processes, including coating the MIP-QD composites on the treated PIs, stripping the Tc from the MIP-QD composites, and sensing the Tc through a fluorescence-quenching mechanism, were optimized and noticed with the difference between the studies. The sensitivity in the dose-response, stability in replicate measurement and storage, and selectivity in imprinting factor and recoveries from bovine serum albumin, fetal bovine serum, and fresh liquid milk, were investigated for the studied sensor
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