Emerging trends on the uptake of fluorescent probes based on glucose analogs by cancer cells: From basic studies to therapeutics.

The cancer cell metabolism, notably characterized by the Warburg effect, has been the focus of intense investigation regarding the mechanisms of the uptake of glucose analogs, opening up perspectives for diagnosis and treatment of cancer disease. In this review, we delve into the ever-evolving landscape of cancer research, centering on fluorescent probes based on glucose analogs. These analogs, resulting from modifications in the carbohydrate structure with functional groups, have stood out as versatile molecules in applications ranging from disease comprehension to therapeutic innovation, especially when combined with fluorescent compounds. Fluorescence-based assays have provided valuable contributions to the revelation of complex biological mechanisms in life sciences. This review presents selected studies from about the past six years up to 2024 related to the use of glucose-based fluorescent probes for the investigation of their uptake profile as well as for therapeutic purposes. We believe that these investigations offer insights into the intricate interaction between glucose analogs and cancer cell metabolism, guiding future research and clinical applications in this field.

Surface coupling of molecularly imprinted polymers as strategy to improve sulfamethoxazole removal from water by carbons produced from spent brewery grain.

This work aims to assess the surface coupling of molecularly imprinted polymers (MIP) on carbon adsorbents produced from spent brewery grain, namely biochar (BC) and activated carbon (AC), as a strategy to improve selectivity and the adsorptive removal of the antibiotic sulfamethoxazole (SMX) from water. BC and AC were produced by microwave-assisted pyrolysis, and MIP was obtained by fast bulk polymerization. Two different methodologies were used for the molecular imprinting of BC and AC, the resulting materials being tested for SMX adsorption. Then, after selecting the most favourable molecular imprinting methodology, different mass ratios of MIP:BC or MIP:AC were used to produce and evaluate eight different materials. Molecular imprinting was shown to significantly improve the performance of BC for the target application, and one of the produced composites (MIP1-BC-s(1:3)) was selected for further kinetic and equilibrium studies and comparison with individual MIP and BC. The kinetic behaviour was properly described by both the pseudo-first and pseudo-second order models. Regarding equilibrium isotherms, they fitted the Freundlich and Langmuir models, with MIP1-BC-s(1:3) reaching a maximum adsorption capacity (qm) of 25 ± 1 µmol g-1, 19 % higher than BC. In comparison with other seven pharmaceuticals, the adsorption of SMX onto MIP1-BC-s(1:3) was remarkably higher, as for the specific recognition of this antibiotic by the coupled MIP. The pH study evidenced that SMX removal was higher under acidic conditions. Regeneration experiments showed that MIP1-BC-s(1:3) provided good adsorption performance, which was stable during five regeneration-reutilization cycles. Overall, this study has demonstrated that coupling with MIP may be a suitable strategy to improve the adsorption properties and performance of biochar for antibiotics removal from water, increasing its suitability for practical applications.

A surface-enhanced infrared absorption spectroscopy (SEIRA) multivariate approach for atrazine detection.

A green, fast and effective multivariate method for the determination of atrazine (ATZ) was developed using conventional infrared equipment furnished with an attenuated total reflectance module (ATR-IR), providing limit of detection (LOD) and limit of quantification (LOQ) in the ranges from 1.9 to 4.6 µg/mL and from 5.6 to 14 µg/mL, respectively. Furthermore, the surface-enhanced infrared absorption (SEIRA) approach was investigated to improve the sensitivity of the measurements and detect ATZ at low concentrations, addressing the compatibility with reference methods. To this end, a substrate formed by silver selenide quantum dots stabilized with mercaptopropionic acid (Ag2Se/MPA), synthesized in aqueous medium by an one-pot synthesis, was used. The spectral data were investigated by univariate and multivariate calibrations, allowing to calculate the enhancement factor (EF) and the multivariate enhancement factor (MEF), respectively. The SEIRA strategy proved to be able to enhance the atrazine signal up to 86-fold, allowing the detection of ATZ at concentrations as low as 0.001 µg/mL.

Fluorescent quantum dot-based nanotool for targeted identification and evaluation of the schistosomiasis circulating cathodic antigen in tissue samples.

Schistosomiasis represents a serious public health problem, a disease for which the circulating cathodic antigen (CCA) is a relevant biomarker. Quantum dots (QDs) are advantageous fluorescent nanoparticles that can be used as specific nanoprobes. In this study, a nanotool based on QDs and anti-CCA antibodies was developed, which, in association with fluorescence microscopy, was applied to trace and evaluate the CCA profile in schistosomiasis-infected tissue samples. Kidney and liver tissues from mice at different disease phases were used as models. QDs and the conjugates were characterized by absorption and emission spectroscopies. Microscopy analyses were used to map and assess CCA accumulation in infected tissue slices in respect to non-infected control samples. The fluorescent microplate assay (FMA) and Zeta potential (ζ) analyses indicated an effective conjugation, which was corroborated by the absence of labeling in non-infected tissue slices (which lack CCA) after incubation with the nanoprobe. Infected liver and kidney tissues exhibited notable staining by the QDs-anti-CCA conjugate. The CCA accumulation increased as follows: 30 < 60 = 120 days post-infection, with 30, 60, and 120 days corresponding to the pre-patent, acute, and beginning of chronic disease phases, respectively. Therefore, this innovative approach, combining imaging acquisition with the sensitivity and specificity of the QDs-anti-CCA conjugate, demonstrated efficiency in locating and comparatively evaluating CCA deposition in biological samples, thereby opening new possibilities for schistosomiasis research.

Advances on chalcogenide quantum dots-based sensors for environmental pollutants monitoring.

Water contamination represents a significant ecological impact with global consequences, contributing to water scarcity worldwide. The presence of several pollutants, including heavy metals, pharmaceuticals, pesticides, and pathogens, in water resources underscores a pressing global concern, prompting the European Union (EU) to establish a Water Watch List to monitor the level of these substances. Nowadays, the standard methods used to detect and quantify these contaminants are mainly liquid or gas chromatography coupled with mass spectrometry (LC/GC-MS). While these methodologies offer precision and accuracy, they require expensive equipment and experienced technicians, and cannot be used on the field. In this context, chalcogenide quantum dots (QDs)-based sensors have emerged as promising, user-friendly, practical, and portable tools for environmental monitoring. QDs are semiconductor nanocrystals that possess excellent properties, and have demonstrated versatility across various sensor types, such as fluorescent, electrochemical, plasmonic, and colorimetric ones. This review summarizes recent advances (2019-2023) in the use of chalcogenide QDs for environmental sensing, highlighting the development of sensors capable of detect efficiently heavy metals, anions, pharmaceuticals, pesticides, endocrine disrupting compounds, organic dyes, toxic gases, nitroaromatics, and pathogens.

Development of Fluorescent Sensors for Biorelevant Anions in Aqueous Media Using Positively Charged Quantum Dots.

Quantum dots (QDs) have captured the attention of the scientific community due to their unique optical and electronic properties, leading to extensive research for different applications. They have also been employed as sensors for ionic species owing to their sensing properties. Detecting anionic species in an aqueous medium is a challenge because the polar nature of water weakens the interactions between sensors and ions. The anions bicarbonate (HCO3-), carbonate (CO32-), sulfate (SO42-), and bisulfate (HSO4-) play a crucial role in various physiological, environmental, and industrial processes, influencing the regulation of biological fluids, ocean acidification, and corrosion processes. Therefore, it is necessary to develop approaches capable of detecting these anions with high sensitivity. This study utilized CdTe QDs stabilized with cysteamine (CdTe-CYA) as a fluorescent sensor for these anions. The QDs exhibited favorable optical properties and high photostability. The results revealed a gradual increase in the QDs' emission intensity with successive anion additions, indicating the sensitivity of CdTe-CYA to the anions. The sensor also exhibited selectivity toward the target ions, with good limits of detection (LODs) and quantification (LOQs). Thus, CdTe-CYA QDs show potential as fluorescent sensors for monitoring the target anions in water sources.