This method was applied during a monitoring activity in an Italian volcanic lake in Viterbo (Lazio Region, Italy), due to a severe algal proliferation in January 2018-March 2019 period and for the assessment of cyanobacteria proliferation risk and of cyanotoxin production in drinking water chain. We reported a novel colorimetric method for highly selective halide ions (Cl-, Br-and I-) recognition by Ag nanoclusters hydrogel (Ag-NCs hydrogel). The Ag-NCs hydrogel could discriminate Cl-, Br-and I- ions from a wide range of environmentally important anions, identified by the distinct UV-vis absorption band changes or the change in the color of Ag-NCs hydrogel. On the basis of this strategy, 20 μM and 200 μM of Cl-, 5 μM and 100 μM of Br-, 5 μM and 100 μM of I- could be recognized within 5 min by UV-vis spectrum and naked eye observation, respectively. The surface color of hydrogel changed from yellow to dark green for Cl-, to brown for Br-, and to deep brown for I-. In addition, this sensing method had been applied successfully to detect chloride anion in real water samples such as tap water, pond water and pure water. Therefore, this rapid, facile, and cost-effective colorimetric assay based on Ag-NCs hydrogel was attractive and promising. Alzheimer’s disease is a debilitating and largely untreatable condition with subtle onset and slow progression over an extensive period of time, which culminate in increasing levels of disability. As Alzheimer’s disease prevalence is expected to grow exponentially in the upcoming decades, there is an urgency to develop analytical technologies for the sensitive, reliable and cost-effective detection of Alzheimer’s disease biomarkers. Biosensors are powerful analytical devices that translate events of biological recognition on physical or chemical transducers into electrical, thermal or optical signals. The high sensitivity and selectivity of biosensors associated with easy, rapid and low-cost determination of analytes have made this discipline one of the most intensively studied in the past decades. This review centers on recent advances, challenges and trends of Alzheimer’s disease biosensing particularly in the effort to combine the unique properties of nanomaterials with biorecognition elements. In the last decade, impressive progresses have been made towards the development of biosensors, mainly electrochemical and optical, for detection of Alzheimer’s disease biomarkers in the pico- and femto-molar range. Nonetheless, advances in multiplexed detection, robustness, stability and specificity are still necessary to ensure an accurate and differentiated diagnosis of this disease. Core-shell SiO2@CIM-80(Al) microspheres were synthesized, characterized, and used as novel sorbent in a dispersive miniaturized solid-phase extraction (D-μSPE) method for the determination of fourteen polycyclic aromatic hydrocarbons (PAHs) in wastewaters by ultra-high performance liquid chromatography coupled to a fluorescence detector (UHPLC-FD). A Doehlert experimental design permitted to optimize the main parameters affecting the microextraction procedure, intending the obtaining of a simple approach. Optimized extraction conditions include 13 mg of SiO2@CIM-80(Al) microparticles (~2 mg CIM-80(Al)), 2.5 min of extraction time, 0.125 mL of acetonitrile (ACN) as desorption solvent and 0.5 min of desorption time. The entire method showed adequate analytical performance with limits of detection down to 5 ng L-1, and inter-day precision lower than 14.1% for a concentration level of 0.5 μg L-1. The extraction capability of SiO2@CIM-80(Al) microspheres was compared to that obtained with commercially available silica microspheres and the neat MOF CIM-80(Al), demonstrating the advantages of the use of MOF core-shell sorbents in D-μSPE. A miniaturized and high sensitive dual channel fluorimeter was developed and evaluated. It employed collinear optical arrangement, a 365 nm and a 470 nm light emitting diodes (LEDs) as light sources, two photodiodes (PDs) integrated with pre-amplifiers as optoelectronic detectors, and a 12.5 mm × 12.5 mm × 45 mm (width × length × height) quartz cuvette as detection cell. The optical parameters such as spectrum compatibility of dual channel, reshaping lens, the common optical path length (COPL), the common focus lens (CFL), as well as working distance of the cuvette were optimized carefully. It was found that the use of shortened optical path and common focal lens could improve the sensitivity of the dual channel fluorimeter significantly. The limits of detection (LODs) for coumarin, aflatoxin B1, fluorescein sodium, and vitamin B2 were 0.002 μg L-1, 0.006 μg L-1, 0.008 μg L-1, and 0.03 μg L-1, respectively. The dual channel fluorimeter can be used for detection of several categories of substance, such as mycotoxins, polycyclic aromatic hydrocarbons, fluorescein, vitamins, and pathogenic microorganisms etc. As a key component, it can also find application in different disciplines such as fluorescent PCR instruments and 96-well plate fluorescence analyzer. The exosomes are emerging as biomarkers for the detection of cancer in early stages, as well as for the follow-up of the patients under treatment. This paper describes the characterization of exosomes derived from three different breast cancer cell lines (MCF7, MDA-MB-231 and SKBR3), and the quantification based on a magneto-actuated immunoassay. The exosomes are separated and preconcentrated on magnetic particles by immunomagnetic separation and labelled with a second antibody conjugated with an enzyme for the optical readout performed with a standard microplate reader. Several molecular biomarkers, including the general tetraspanin CD9, CD63 and CD81, and the receptors related with cancer (CD24, CD44, CD54, CD326 and CD340) were studied either for the immunomagnetic separation or the labelling, in different formats. After a rational selection of the biomarkers, this immunoassay is able to detect 105 exosomes μL-1 directly in human serum without any treatment, such as ultracentrifugation. The interference from free receptors in the samples could easily be prevented by performing the immunomagnetic separation with antiCD81 modified magnetic particles and the labeling based on either CD24 or CD340. Furthermore, the differentiation of healthy donors and breast cancer individuals was also demonstrated. This approach is a highly suitable alternative method for flow cytometry, providing a sensitive method for the multiplex detection but using instrumentation widely available in resource-constrained laboratories and requiring low-maintenance, as is the case of a microplate reader operated by filters. Combining electrospray ionization mass spectrometry (ESI-MS) with circular dichroism (CD) spectroscopy, a G-rich sequence from miR-92a promoter region was discovered to form a parallel G-quadruplex structures in KCl or NH4OAc solution. In case of high concentration of NH4OAc, the ESI mass spectra showed peaks of a dimeric G-quadruplex structure with 4 ammonium ions. Meanwhile, palmatine, a natural alkaloid, was screened by ESI-MS to bind with the miR-92a G-quadruplex affinitively. The variable temperature experiment of CD also proved that high concentration of NH4OAc or palmatine could promote the stability of the dimeric G-quadruplex structure. To get the specific characteristics of the miR-92a G-quadruplex structure, systematic mutations of guanine were tested. Based on the number of NH4+ or ligands, the important guanines involved in the G-quadruplex could be determined. Considering the importance of involved guanines and the number of G-quartets, we speculated an interlocked dimeric parallel G-quadruplex as a possible conformation of the miR-92a promoter G-quadruplex. All results obtained from ESI-MS and CD illustrate structure characteristics of the miR-92a G-quadruplex, which is a promising method for preliminary structural analysis of G-quadruplexes. Besides, this study also provides a strategy for regulating the functions of microRNA by exploring and targeting higher-order structures of miRNAs. A semi-automated and sensitive method was developed for simultaneous determination of the six most consumed artificial sweeteners (AS) in surface waters using thin-film solid-phase microextraction (TF-SPME) and high-performance liquid chromatography (HPLC). A triple quadrupole mass spectrometer and an electrospray ionization source (ESI-MS) run in negative ionization and multiple reaction monitoring modes were employed for instrumental analysis. The TF-SPME method was optimized for the extraction phase, sample pH, desorption solvent, extraction time, and desorption time. In-house-synthetized-hydrophilic-lipophilic balance weak anion exchange (HLB-WAX) particles imbedded within a polyacrylonitrile (PAN) binder were selected as the extraction phase for the thin-film coating due to their cost-effectiveness and enhanced sensitivity for artificial sweeteners. Suitable analytical parameters that include linearity (R2 > 0.9914), recovery > 80%, inter, and intra-reproducibility less than 18% were obtained for the AS compounds studied. The developed method estimated limits of detection (LODs) ranging from 0.004 to 0.038 ng mL-1 The SPME method was successfully applied for the determination of ultra-trace levels of AS in water samples collected from Grand River (Ontario, Canada), downstream of three municipal wastewater treatment plants (WWTPs). Concentrations ranging from 0.03 to 20.3 ng mL-1 were found for the AS compounds studied. The ability to discover minute differences between samples or sample classes for gas chromatography coupled to mass spectrometry (GC-MS) can be a challenging endeavor, especially when those differences are not a priori. Fisher ratio (F-ratio) analysis is an apt technique to probe the differences between GC-MS chromatograms. F-ratio analysis is a supervised, non-targeted, discovery-based method that compares two different samples (or sample classes) to reduce the GC-MS dataset into a hit list composed of class distinguishing compounds. Three different F-ratio techniques, peak table, tile, and pixel-based were used to „discover” nine non-native analytes that were spiked into gasoline at four different nominal concentrations of 250, 85, 25, 5 parts-per-million (ppm). For the tile and pixel-based F-ratio calculations, a novel methodology is introduced to improve the sensitivity of the F-ratio calculations while reducing false positives. Furthermore, we use a combinatorial technique using null class comparisons, termed null distribution analysis, to determine a statistical F-ratio cutoff for analysis of the hit lists. The pixel-based algorithm was the most sensitive method and was able to „discover” all nine spiked analytes at a nominal concentration of 250 ppm albeit with one false positive interspersed towards the bottom of the hit list. The pixel-based software was also able to „discover” more of the spiked analytes at the lower concentrations with seven of the spiked analytes „discovered” at 85 ppm, four of the spiked analytes „discovered” at 25 ppm, and one analyte „discovered” at 5 ppm. Rapid detection of foodborne pathogens is crucial to prevent the outbreaks of foodborne illnesses. In this study, a sensitive electrochemical aptasensor was developed using aptamer coated gold interdigitated microelectrode for target capture and impedance measurement, and antibody modified nickel nanowires (NiNWs) for target separation and impedance amplification. First, the interdigitated microelectrode was modified with the biotinylated aptamers against Salmonella typhimurium through electrostatic absorption of streptavidin onto the microelectrode and streptavidin-biotin binding. Then, the target Salmonella cells were magnetically separated and concentrated using the NiNWs modified with the anti-Salmonella typhimurium antibodies to form the bacteria-NiNW complexes, and incubated on the microelectrode to form the aptamer-bacteria-NiNW complexes. After an external arc magnetic field was developed and applied to control the NiNWs to form conductive NiNW bridges across the microelectrode, the enhanced impedance change of the microelectrode was measured and used to determine the amount of target bacteria.