Superparamagnetic
nanoparticles (SPMNPs) have attracted interest
for various biomedical applications due to their unique magnetic behavior,
excellent biocompatibility, easy surface modification, and low cost.
Their unique magnetic properties, superparamagnetism, and magnetophoretic
mobility have led to their inclusion in immunoassays to enhance biosensor
sensitivity and allow for rapid detection of various analytes. In
this review, we describe SPMNP characteristics valuable for incorporation
into biosensors, including the use of SPMNPs to increase detection
capabilities of surface plasmon resonance and giant magneto-resistive
biosensors. The current status of SPMNP-based immunoassays to improve
the sensitivity of rapid diagnostic tests is reviewed, and suggested
strategies for the successful adoption of SPMNPs for immunoassays
are presented.
In situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming groundwater contaminants into harmless by‐products. Owing to oxidant persistence, groundwater samples collected at hazardous waste sites may contain both the contaminant(s) and the oxidant in a “binary mixture.” Binary mixtures composed of sodium persulfate (2.5 g/L; 10.5 mM) and volatile organic compounds (VOCs) (benzene, toluene, m‐xylene, perchloroethylene, trichloroethylene) were analyzed to assess the impact on the quality of the sample. A significant decline (49 to 100%) in VOC concentrations was measured in binary mixtures using gas chromatography (GC) purge and trap, and GC mass spectroscopy headspace methods. Preservation of the binary mixture samples was achieved through the addition of ascorbic acid (99 to 100% VOC average recovery). High concentrations of ascorbic acid (42 to 420 mM) did not interfere in the measurement of the VOCs and did not negatively impact the analytical instruments. High concentrations of ascorbic acid favored the reaction between persulfate and ascorbic acid while limiting the reaction between persulfate and VOCs. If an oxidant is detected and the binary sample is not appropriately preserved, the quality of the sample is likely to be compromised.
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