Soil and groundwater contamination by lead and cadmium poses significant environmental and health risks, necessitating the development of rapid and accurate field monitoring techniques, which are currently lacking. Although solid-phase colorimetric microProbing imaging offers a promising solution, fine-tuning the hydrophilic/hydrophobic microenvironment of lead or cadmium molecular sensors within the microProbing material is essential for achieving rapid and accurate detection. Here, we report a method to covalently bond xylenol orange (a lead sensor) or physically adsorb dithizone (a cadmium sensor) onto the hydrophilic or hydrophobic entities of TentaGel resins, enabling uniform sensor loading, selective sequestration, and rapid microProbing of soil and groundwater lead or cadmium. Through microenvironment fine-tuning, the method achieved high sensitivity, with detection limits of 28 ppm and 9.9 ppb for soil and groundwater lead, and 50 ppb and 6.8 ppb for soil and groundwater cadmium, respectively. It accurately detected soil and groundwater lead from an economic development zone in Shenzhou (Hebei Province) and cadmium from a mine in Daye (Hubei Province), China. A portable microProbing device was also custom-designed and fabricated. With this device, the microProbing method shows great promise for field monitoring of other heavy metals in contaminated lands.
Bin Jiao,Wei Zhou,Yikun Liu,Wenpeng Zhang,Zheng Ouyang
Direct sampling of lipids from tissues for direct mass spectrometry (MS) analysis allows a quick profiling of lipidome, which is important for biomedical applications. In this work, we developed a polyporous polymeric membrane (PPM) microprobe for highly efficient sampling of lipids directly from tissue samples. The PPM was prepared by polypropylene with pores as large of 10 μm, facilitating the permeation of lipids from tissue surfaces. The PPM was coated onto a stainless steel wire with a thickness of ∼100 μm. The entire analysis procedure includes sampling of the lipids in tissue, washing the probe, and extraction spray ionization for MS analysis. The effectiveness was validated by analyzing mouse brain tissue samples. It showed high recoveries for a series of lipid classes in comparison with total lipid extraction method. Further demonstration was carried out with analysis of tissue samples from mouse liver, stomach, kidney and legs. With high physical strength and good chemical stability, the microprobe was also demonstrated for sampling lipids inside mouse kidney tissue samples. By incorporating a photochemical derivatization, a workflow was also developed for fast detection of lipid C C isomers in tissue samples. Finally, a microprobe array was also developed for simultaneous sampling of lipids from multiple sites on tissue surfaces.
Zhe Wu,Yingjie Wang,Yufei Wang,Kaining Zhang,Yongchao Lai
Malondialdehyde (MDA) is an endogenous genotoxic product of lipid peroxidation and its accumulation in the human body is associated with various diseases. To accurately understand the role of MDA in physiological and pathological processes, it is of great significance to develop a robust and reliable method for rapid detection of MDA. Hence, we proposed a surface-enhanced Raman spectroscopy (SERS) based method for MDA analysis, which employed 4-aminophenylthiophenol (PATP) as a SERS microprobe to recognize and quantify MDA. Qualitative analysis of MDA was performed using the fingerprint Raman spectrum of MDA adducts, and quantitative analysis of MDA was conducted using the characteristic peak of PATP at 1083 cm −1 as the internal standard. MDA detection can be performed in a mild reaction environment and the detection limit was below 0.50 μM. The proposed method successfully detected MDA in fresh blood samples and found satisfactory recovery rates in spiked samples. The proposed method allows reliable detection of endogenous toxic compounds in blood plasma, which is of great significance for monitoring oxidative stress indicators, such as lipid peroxidation rate and intensity, potential antioxidant capacity, and the degree of tissue peroxidation damage.
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