Detection of Cadmium in Human Biospecimens by a Cadmium-Selective Whole-Cell Biosensor Based on Deoxyviolacein.

Cadmium poses a severe health risk, impacting various bodily systems. Monitoring human exposure is vital. Urine and blood cadmium serve as critical biomarkers. However, current urine and blood cadmium detection methods are expensive and complex. Being cost-effective, user-friendly, and efficient, visual biosensing offers a promising complement to existing techniques. Therefore, we constructed a cadmium whole-cell biosensor using CadR10 and deoxyviolacein pigment in this study. We assessed the sensor for time-dose response, specific response to cadmium, sensitivity response to cadmium, and stability response to cadmium. The results showed that (1) the sensor had a preferred signal-to-noise ratio when the incubation time was 4 h; (2) the sensor showed excellent specificity for cadmium compared to the group 12 metals and lead; (3) the sensor was responsive to cadmium down to 1.53 nM under experimental conditions and had good linearity over a wide range from 1.53 nM to 100 µM with good linearity (R2 = 0.979); and (4) the sensor had good stability. Based on the excellent results of the performance tests, we developed a cost-effective, high-throughput method for detecting urinary and blood cadmium. Specifically, this was realized by adding the blood or urine samples into the culture system in a particular proportion. Then, the whole-cell biosensor was subjected to culture, n-butanol extraction, and microplate reading. The results showed that (1) at 20% urine addition ratio, the sensor had an excellent curvilinear relationship (R2 = 0.986) in the range of 3.05 nM to 100 µM, and the detection limit could reach 3.05 nM. (2) At a 10% blood addition ratio, the sensor had an excellent nonlinear relationship (R2 = 0.978) in the range of 0.097-50 µM, and the detection limit reached 0.195 µM. Overall, we developed a sensitive and wide-range method based on a whole-cell biosensor for the detection of cadmium in blood and urine, which has the advantages of being cost-effective, ease of operation, fast response, and low dependence on instrumentation and has the potential to be applied in the monitoring of cadmium exposure in humans as a complementary to the mainstream detection techniques.

High-throughput screening of human mercury exposure based on a low-cost naked eye-recognized biosensing platform.

Whole-cell biosensors could be helpful for in situ disease diagnosis. However, their use in analyzing biological samples has been hindered by unstable responses, low signal enhancement, and growth inhibition in complex media. Here, we offered a solution by building a visual whole-cell biosensor for urinary mercury determination. With deoxyviolacein as the preferred signal for the mercury biosensor for the first time, it enabled the quantitative detection of urinary mercury with a favorable linear range from 1.57 to 100 nM. The biosensor can accurately diagnose urine mercury levels exceeding the biological exposure index with 95.8% accuracy. Thus, our study provided a biosensing platform with great potential to serve as a stable, user-friendly, and high-throughput alternative for the daily monitoring or estimating of urinary mercury.

[Detecting the isoflurane in the air of workplaces with chromatographic method].

OBJECTIVE: To establish a solvent desorption Gas chromatographic method for detecting the isoflurane in air of workplaces. METHODS: This method is based on "Standardization of methods for determination of toxic substances in workplace air". RESULTS: This method presents the linear relation with the minimum detectable limit 1.0 µg/ml and the minimum detectable concentration 0.07 mg/m(3). The precision (RSD) was 0.5% ∼ 5.0%, the mean dsorption efficiencies were 96.7% ∼ 98.9%, the absorption efficiencies were 92.1% ∼ 100%, the breakthrough volume was 3.7 mg isoflurane/100 mg active carbon. Other volatile organic solvents (Sevoflurane, Enflurane and Ethyl Alcohol) did not interfere the detection. The sample could be stored in the active carbon tube at least for 10 days. CONCLUSION: This method is meet the requirement of GBZ/T 210.4-2008 "Guide for establishing occupational health standards-Part4: Determination methods of air chemicals in workplace" and is feasible for determining the isoflurane in the air of workplaces.

[Simultaneous determination of seven chemicals of halogenated alkanes and aromatic hydrocarbons in the air of workplace by gas chromatography].

OBJECTIVE: To establish a gas chromatographic method for determination of halogenated alkanes and aromatic hydrocarbons including trichloromethane, 1,2-dichloroethane, carbon tetrachloride, benzene, toluene, ethylbenzene and xylene in the air of workplace. METHODS: After the air samples collected with activated carbon tubes and desorbed with CS(2), the target toxicants were separated with FFAP capillary columns and detected with flame ionization detector. RESULTS: The coefficient of correlation was above 0.999 and the lowest detectable concentrations were 0.2 ∼ 3.6 mg/m(3) with the RSD of 1.2% ∼ 4.6%. The desorption efficiencies was 94.9% ∼ 100.7%. CONCLUSION: The method shows lower detection limit, high accuracy and precision. It is feasible for determination of the seven halogenated alkanes and aromatic hydrocarbons in the air of workplace.