Abstract
Metal ions in high concentrations can pollute the marine environment. Human activities and industrial pollution are the causes of Cu2+ contamination. Here, we report our discovery of an enzyme method-based microfluidic that can be used to rapidly detect Cu2+ in seawater. In this method, Cu2+ is reduced to Cu+ to inhibit horseradish peroxidase (HRP) activity, which then results in the color distortion of the reaction solution. The chip provides both naked eye and spectrophotometer modalities. Cu2+ concentrations have an ideal linear relationship, with absorbance values ranging from 3.91 nM to 256 μM. The proposed enzyme method-based microfluidic chip detects Cu2+ with a limit of detection (LOD) of 0.87 nM. Other common metal ions do not affect the operation of the chip. The successful detection of Cu2+ was achieved using three real seawater samples, verifying the ability of the chip in practical applications. Furthermore, the chip realizes the functions of two AND gates in series and has potential practical implementations in biochemical detection and biological computing.
Highlights
Marine environmental pollution is an increasingly acute global problem [1,2]
The results showed that Cu2+ had a slight inhibitory effect on ng/mL horseradish peroxidase (HRP), respectively (Figure 2a)
The HRP-TMB color reaction is a well-known technique in biochemical detection
Summary
Marine environmental pollution is an increasingly acute global problem [1,2]. Trace metals are essential components of biogeochemistry; high concentrations of metals can cause persistent harm to the marine environment [3,4]. Copper ions found in seawater mainly exist in the form of Cu2+ in the concentration of fM-pM [5]. Concentrations vary depending on the location, temperature, acidity, salinity, and depth of the seawater [6]. The concentration of copper ions in the ocean can rise to μM as a consequence of human activities and industrial pollution. High concentrations of copper ions are toxic, to the metabolisms of marine organisms [7]; for example, high levels of copper ions can interfere with the fertilization of sea urchins and negatively impact algae survival [8,9]. Excess copper ions can lead to diseases such as anemia and Alzheimer’s disease [10,11,12].
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