Alkaline Phosphatase Immobilized CdTe/ZnS Quantum Dots for Dual-Purpose Fluorescent and Electrochemical Detection of Methyl Paraoxon

Exploring Various Photochemical Processes in Optical Sensing of Pesticides by Luminescent Nanomaterials: A Concise Discussion on Challenges and Recent Advancements

Food safety is a burning global issue in this present era. The prevalence of harmful food additives and contaminants in everyday food is a significant cause for concern as they can adversely affect human health. More particularly, among the different food contaminants, the use of excessive pesticides in agricultural products is severely hazardous. So, the optical detection of residual pesticides is an effective strategy to counter the hazardous effect and ensure food safety. In this perspective, nanomaterials have played a leading role in defending the open threat against food safety instigated by the reckless use of pesticides. Now, nanomaterial-based optical detection of pesticides has reached full pace and needs an inclusive discussion. This Review covers the advancement of photoprocess-based optical detection of pesticides categorically using nanomaterials. Here, we have thoroughly dissected the photoprocesses (aggregation and aggregation-induced emission (AIE), charge transfer and intramolecular charge transfer (ICT), electron transfer and photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), hydrogen bonding, and inner filter effect) and categorically demarcated their significant role in the optical detection of pesticides by luminescent nanomaterials over the last few years.

Advances in Ultra-small Fluorescence Nanoprobes for Detection of Metal Ions, Drugs, Pesticides and Biomarkers

Identification of trace level chemical species (drugs, pesticides, metal ions and biomarkers) plays key role in environmental monitoring. Recently, fluorescence assay has shown significant advances in detecting of trace level drugs, pesticides, metal ions and biomarkers in real samples. Ultra-small nanostructure materials (metal nanoclusters (NCs), quantum dots (QDs) and carbon dots (CDs)) have been integrated with fluorescence spectrometer for sensitive and selective analysis of trace level target analytes in various samples including environmental and biological samples. This review summarizes the properties of metal NCs and ligand chemistry for the fabrication of metal NCs. We also briefly summarized the synthetic routes for the preparation of QDs and CDs. Advances of ultra-small fluorescent nanosensors (NCs, QDs and CDs) for sensing of metal ions, drugs, pesticides and biomarkers in various sample matrices are briefly discussed. Additionally, we discuss the recent challenges and future perspectives of ultra-small materials as fluorescent sensors for assaying of wide variety of target analytes in real samples.

Supramolecular host-guest interaction-driven electrochemical recognition for pyrophosphate and alkaline phosphatase analysis

Herein, we report an electrochemical biosensor based on the supramolecular host-guest recognition between cucurbit[7]uril (CB[7]) and L -Phenylalanine-Cu(II) Complex for pyrophosphate (PPi) and alkaline phosphatase (ALP) analysis. First, L -Phe-Cu(II) Complex is simply synthesized by the complexation of Cu(II) (metal node) with L -Phe (bioorganic ligand), which can be immobilized onto CB[7] modified electrode via host-guest interaction of CB[7] and L -Phe. In this process, the signal of the Complex triggered electro-catalytic reduction of H 2 O 2 can be captured. Next, in the view of strong chelation between PPi and Cu(II), a biosensing system of the model "PPi and Cu(II) premixing, then adding L -Phe" is designed and the platform can be applied for PPi analysis well by hampering the formation of L -Phe-Cu(II) Complex. Along with ALP introduction, PPi can be hydrolyzed into orthophosphate (Pi), where abundant Cu(II) ions are released to form L -Phe-Cu(II) Complex, which gives rise to the catalytic reaction of Complex to H 2 O 2 reduction. The quantitative analysis of H 2 O 2 , PPi and ALP activity is achieved successfully and the detection of limits are 0.067 μM, 0.42 μM and 0.09 mU/mL ( S / N =3), respectively. With the merits of high sensitivity and selectivity, cost-effectiveness, and simplification, our developed analytical system has great potential to act on diagnosis and treatment of ALP-related diseases.

A two-step strategy for simultaneous dual-mode detection of methyl-paraoxon and Ni (Ⅱ)

Exogenous pollution of Chinese medicinal materials by pesticide residues and heavy metal ions has attracted great attention. Relying on the rapid development of nanotechnology and multidisciplinary fields, fluorescent techniques have been widely applied in contaminant detection and pollution monitoring due to their advantages of simple preparation, low cost, high throughput and others. Most importantly, synchronous detection of multi-targets has always been pursued as one of the major goals in the design of fluorescent probes. Herein, we firstly develop a simultaneous sensing method for methyl-paraoxon (MP) and Nickel ion (Ni, Ⅱ) by using carbon based fluorescent nanocomposite with ratiometric signal readout and nanozyme. Notably, the designed system showed excellent effectiveness even when the two pollutants co-exist. Under the optimum conditions, this method provides low limits of detection of 1.25 µM for methyl-paraoxon and 0.01 µM for Ni (Ⅱ). To further verify the reliability, recovery studies of these two analytes were performed on ginseng radix et rhizoma, nelumbinis semen, and water samples. In addition, smartphone-based visual analysis has been introduced to expand its applicability in point of care detection. This work not only expands the application of the dual-mode approach to pollutant detection, but also provides insights into the analysis of multiple pollutants in a single assay.