Rapid detection of trace Cu²⁺ using an l‐cysteine based interdigitated electrode sensor integrated with AC electrokinetic enrichment

Abstract

Copper is an indispensable trace element for human health. Too much or too little intake of copper ion (Cu2+) can lead to its own adverse health conditions. Therefore, detection of Cu2+ is always of vital importance. In this work, a simple sensor was developed for rapid detection of trace Cu2+ in water, in which L‐cysteine (Cys) as a molecular probe was self‐assembled on a gold interdigital electrode to form a monolayer for specific capture of Cu2+. The interfacial capacitance of interdigital electrode was detected to indicate the target adsorption level under an AC signal working as the excitation to induce directed movement and enrichment of Cu2+ to the electrode surface. This sensor reached a limit of detection of 4.14 fM and a satisfactory selectivity against eight other ions (Zn2+, Hg2+, Pb2+, Cd2+, Mg2+, Fe2+, As3+, and As5+). Testing of spiked tap water was also performed, demonstrating the sensor's usability. This sensor as well as the detection method shows a great application potential in fields such as environmental monitoring and medical diagnosis.

Real-time, selective, and low-cost detection of trace level SARS-CoV-2 spike-protein for cold-chain food quarantine

“…The S-protein is tested with ten-fold increase from 10 −5 to 10 −1 ng/mL in 0.1× PBS solution. Here, the upper-limit concentration of 10 −1 ng/mL is determined by observing the saturation phenomenon 32 , 33 at 1 ng/mL (illustrated in Fig. S 1a, b in Supplementary Material).…”

Real-time Sensing of Trace Biomarkers from Viruses with a Microfluidic Immunosensor: A Case Study of SARS-CoV-2 Detection in Cold-chain Food

“…The S-protein is tested with tenfold increase from 10 -5 to 10 -1 ng/mL in 0.1×PBS solution. Here the upper-limit concentration of 10 -1 ng/mL is determined by observing the saturation phenomenon [31,32] This indicates the sensor's primary performance of output monotonicity In Fig. 1a, the linearity of the transient curves become worse after 10 s when the concentration is high.…”

Real-time Sensing of Trace Biomarkers from Viruses with a Microfluidic Immunosensor: A Case Study of SARS-CoV-2 Detection in Cold-chain Food

“…The S-protein is tested with tenfold increase from 10 -5 to 10 -1 ng/mL in 0.1×PBS solution. Here the upper-limit concentration of 10 -1 ng/mL is determined by observing the saturation phenomenon [32,33] at 1 ng/mL (illustrated in Figure S1a 10 -1 ng/mL is equivalent to the response from S-protein at 4.27×10 -4 ng/mL calculated using the calibration line, then the selectivity ratio of this sensor is calculated to be 234: 1 (10 -1 ng/mL: 4.27×10 -4 ng/mL). Because N-protein is also a valuable marker for SARS-CoV-2 recognition, a weak response can help recognize the target in deed.…”

“…The S-protein is tested with tenfold increase from 10 -5 to 10 -1 ng/mL in 0.1×PBS solution. Here the upper-limit concentration of 10 -1 ng/mL is determined by observing the saturation phenomenon [32,33] at 1 ng/mL (illustrated in Figure S1a, b in supporting information).…”