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Saltwater intrusion in a coastal region is one of the major issues facing the agricultural, domestic, and industrial sectors. Groundwater withdrawal for an increasing population and agricultural and industrial demands are the main reasons for saltwater intrusion into coastal aquifers. Saltwater intrusion into freshwater aquifers directly affects a population's health, economy, and social development. This study explores an innovative approach to modeling saltwater intrusion into freshwater using a prey–predator model. Freshwater is analogized as the prey and saltwater as the predator, providing a unique perspective on understanding this phenomenon. The present model was formulated using a balance of freshwater and saltwater and is applicable to coastal aquifers. An amount of freshwater withdrawal such that the volume of saltwater does not produce adverse impacts is predicted graphically. Based on a certain simulation, the current model suggests that if the withdrawal rate drops to 50%, freshwater is projected to surpass saltwater dominance for about 90 years. The model has been validated through a benchmark saltwater intrusion problem. [ABSTRACT FROM AUTHOR]

Ferroptosis is a recently identified form of regulated cell death characterized by iron accumulation and lipid peroxidation. Numerous functions for ferroptosis have been identified in physiological as well as pathological processes, most notably in the treatment of cancer. The intricate balance of redox homeostasis is profoundly altered during ferroptosis, leading to alteration in cellular microenvironment. One such microenvironment is viscosity among others such as pH, polarity, and temperature. Therefore, understanding the dynamics of ferroptosis associated viscosity levels within organelles is crucial. To date, there are a very few reviews that detects ferroptosis assessing reactive species. In this review, we have summarized organelle's specific fluorescent probes that detects dynamics of microviscosity during ferroptosis. Also, we offer the readers an insight of their design strategy, photophysics and associated bioimaging concluding with the future perspective and challenges in the related field. [ABSTRACT FROM AUTHOR]

Groundwater quality is one of the major concerns. Quality of the groundwater directly impacts human health, growth of plants and vegetables. Due to the severe impacts of inadequate water quality, it is imperative to find a swift and economical solution. Water quality prediction may help us to manage water resources properly. The present study has been carried out considering thirty-seven water sample data points form the Pindrawan tank command area of Raipur district, Chhattisgarh, India. A total of nineteen physicochemical parameters were measured, out of which seventeen parameters were used to compute the weight-based groundwater quality index (WQI). In this present work, the primary goal is to identify the most effective parameters for WQI prediction. Out of the seventeen parameters tested, the Mann—Whitney—Wilcoxon (MWW) statistical test has revealed that five parameters Fe, Cr, Na, Ca, and Mg hold a strong statistical significance in distinguishing between drinkable and non-drinkable water. Out of these five parameters, Cr is the only parameter that maintains a different range of values for drinkable water and non-drinkable water. To validate the efficiency of these statistically significant parameters, machine learning techniques like Artificial Neural Networks (ANN) and Logistic Regression (LR) were used. The experimental results clearly demonstrate that out of all the seventeen parameters tested, utilizing only Cr yields remarkably high classification accuracy. 'Cr' achieved an accuracy of 91.67% using artificial neural networks. This is much higher than the accuracy of 66.67% obtained using a parameter set with all seventeen parameters. The proposed methodology achieved good accuracy when classifying water samples into drinkable and non-drinkable water using only one parameter, 'Cr'. [ABSTRACT FROM AUTHOR]

Functional fluorophores represent an emerging research field, distinguished by their diverse applications, especially in sensing and cellular imaging. After the discovery of quinine sulfate and subsequent elucidation of the fluorescence mechanism by Sir George Stokes, research in the field of fluorescence gained momentum. Over the past few decades, advancements in sophisticated instruments, including super-resolution microscopy, have further promoted cellular imaging using traditional fluorophores. These advancements include deciphering sensing mechanisms via photochemical reactions and scrutinizing the applications of fluorescent probes that specifically target organelles. This approach elucidates molecular interactions with biomolecules. Despite the abundance of literature illustrating different classes of probe development, a concise summary of newly developed fluorophores remains inadequate. In this review, we systematically summarize the chronological discovery of traditional fluorophores along with new fluorophores. We briefly discuss traditional fluorophores ranging from visible to near-infrared (NIR) in the context of cellular imaging and in vivo imaging. Furthermore, we explore ten new core fluorophores developed between 2007 and 2022, which exhibit advanced optical properties, providing new insights into bioimaging. We illustrate the utilization of new fluorophores in cellular imaging of biomolecules, such as reactive oxygen species (ROS), reactive nitrogen species (RNS), and proteins and microenvironments, especially pH and viscosity. Few of the fluorescent probes provided new insights into disease progression. Furthermore, we speculate on the potential prospects and significant challenges of existing fluorophores and their potential biomedical research applications. By addressing these aspects, we intend to illuminate the compelling advancements in fluorescent probe development and their potential influence across various fields. [ABSTRACT FROM AUTHOR]

A study using mathematical modeling has been conducted to analyze how both man-made and natural sources of contaminants affect various layers of an aquifer-aquitard system. The xy-, yz-, and zx-plane have been used to depict the locations where the natural sources of contaminant occur on the xz- and yz-plane, and where the man-made sources occur, on the xy-plane. It is assumed that the sources occurring in different planes are constant, while the velocity of groundwater flow has been considered only along the x-axis. A three-dimensional advection dispersion equation (ADE) has been used to accurately model the flow of groundwater and contaminants through a porous medium. Three distinct sources exert their influence on three separate planes throughout the entire duration of this study, thus making it possible to model these sources using initial conditions. This study presents a profile of contaminant concentration in space and time when constant sources are located on different planes. Some physical assumptions have been considered to make the model relatable to real-world phenomena. Often, finding stability conditions for numerical solutions becomes difficult, so an unconditionally stable solution is more appreciable. The homotopy analysis method (HAM), a method known for its unconditional stability, has been used to solve a three-dimensional mathematical model (ADE) along with its initial conditions. Man-made sources show more impact than equal-strength natural sources in the aquifer-aquitard system. [ABSTRACT FROM AUTHOR]

The intracellular pH (pHi) in organelles, including mitochondria, endoplasmic reticulum, lysosomes, and nuclei, differs from the cytoplasmic pH, and thus maintaining the pH of these organelles is crucial for cellular homeostasis. Alterations in the intracellular pH (ΔpHi) in organelles lead to the disruption of cell proliferation, ion transportation, cellular homeostasis, and even cell death. Hence, accurately mapping the pH of organelles is crucial. Accordingly, the development of fluorescence imaging probes for targeting specific organelles and monitoring their dynamics at the molecular level has become the forefront of research in the last three decades. Among them, ratiometric fluorescent probes minimize the interference from the excitation wavelength of light, auto-fluorescence from probe concentration, environmental fluctuations, and instrument sensitivity through self-correction compared to monochromatic fluorescent probes, which are known as turn-on/off fluorescent probes. Small-molecular ratiometric fluorescent probes for detecting ΔpHi are challenging yet demanding. To date, sixty-two ratiometric pH probes have been reported for monitoring internal pH alterations in cellular organelles. However, a critical review on organelle-specific ratiometric probes for pH mapping is still lacking. Thus, in the present review, we report the most recent advances in ratiometric pH probes and the previous data on the role of mapping the ΔpHi of cellular organelles. The development strategy, including ratiometric fluorescence with one reference signal (RFRS) and ratiometric fluorescence with two reversible signals (RFRvS), is systematically illustrated. Finally, we emphasize the major challenges in developing ratiometric probes that merit further research in the future. [ABSTRACT FROM AUTHOR]

Mitochondria are the powerhouse of the cell and function at pH ∼8.0. Dysfunctions of mitochondria, includes mitochondrial damage, leading to pH alteration. Hence, researchers aim to develop efficient pH probes for tracking mitochondrial pH dynamics. Herein, we developed a PET‐based fluorescent probe for pH monitoring during mitochondrial dysfunctions. Three derivatives were synthesized with a variable spacer's length in pentacyclic pyridinium fluorophores (PM‐C2, PM‐C3, and PM‐C6). An efficient electron transfers from the receptor (tertiary amine) was observed in the case of PM‐C2 compared to the other two derivatives. This PET process was inhibited when tertiary amine was protonated in acidic pH. However, PM‐C3 showed minimal fluorescence intensity at similar conditions and almost negligible change in case of PM‐C6, suggesting poor PET process for both the derivatives. Furthermore, DFT/TD‐DFT quantum chemical calculation well supported this optical phenomena and PET process. Biocompatible, photostable, and mitochondria‐specific PM‐C2 could monitor pH dynamics during mitochondrial damage which were engulfed by lysosome, also known as mitophagy. This mitophagy process were induced by rapamycin and starvation, which can be monitored by turn‐on fluorescence enhancement. This process was further validated by tracking Parkin‐protein translocation from cytoplasm to damaged mitochondria using our developed probe. [ABSTRACT FROM AUTHOR]

Esterases enzymes regulate the body's homeostasis by catalyzing the hydrolysis of various esters. These are also involved in protein metabolism, detoxification, and signal transmission. Most importantly, esterase plays a significant role in cell viability and cytotoxicity assays. Hence, developing an efficient chemical probe is essential for monitoring the esterase activity. Several fluorescent probes for esterase have also been reported targeting cytosol and lysosomes. However, the ability to create efficient probes is constrained due to a lack of understanding of the esterase's active site for hydrolyzing the substrate. In addition, the fluorescent turn‐on may limit efficient monitoring. Herein, we have developed a unique fluorescent probe, PM‐OAc, to monitor mitochondrial esterase enzyme activity ratiometrically. This probe exhibited a bathochromic wavelength shift with esterase enzyme in alkaline pH (pH∼8.0) due to an intramolecular charge transfer (ICT) process. The phenomenon is well supported by TD‐DFT calculation. Moreover, the substrate (PM‐OAc) binding at the active site of esterase and its catalytic mechanism to hydrolyze the ester bond are elucidated by molecular dynamics (MD) simulation and QM/MM (Quantum mechanics/molecular mechanics) calculations, respectively. Fluorescent image‐based analysis of the cellular environment reveals that our probe can distinguish between live and dead cells based on esterase enzyme activity. [ABSTRACT FROM AUTHOR]

Mitochondria are valuable subcellular organelles and play crucial roles in redox signaling in living cells. Substantial evidence proved that mitochondria are one of the critical sources of reactive oxygen species (ROS), and overproduction of ROS accompanies redox imbalance and cell immunity. Among ROS, hydrogen peroxide (H2O2) is the foremost redox regulator, which reacts with chloride ions in the presence of myeloperoxidase (MPO) to generate another biogenic redox molecule, hypochlorous acid (HOCl). These highly reactive ROS are the primary cause of damage to DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and proteins, leading to various neuronal diseases and cell death. Cellular damage, related cell death, and oxidative stress are also associated with lysosomes which act as recycling units in the cytoplasm. Hence, simultaneous monitoring of multiple organelles using simple molecular probes is an exciting area of research that is yet to be explored. Significant evidence also suggests that oxidative stress induces the accumulation of lipid droplets in cells. Hence, monitoring redox biomolecules in mitochondria and lipid droplets in cells may give a new insight into cell damage, leading to cell death and related disease progressions. Herein, we developed simple hemicyanine-based small molecular probes with a boronic acid trigger. A fluorescent probe AB that could efficiently detect mitochondrial ROS, especially HOCl, and viscosity simultaneously. When the AB probe released phenylboronic acid after reacting with ROS, the product AB–OH exhibited ratiometric emissions depending on excitation. This AB–OH nicely translocates to lysosomes and efficiently monitors the lysosomal lipid droplets. Photoluminescence and confocal fluorescence imaging analysis suggest that AB and corresponding AB–OH molecules are potential chemical probes for studying oxidative stress. [ABSTRACT FROM AUTHOR]

In this article, an incisive analysis had been carried out to investigate the impact of air pollution on groundwater through a water reservoir. The primary objective of the present work was to develop a mathematical model that shows the direct impact of air pollution on groundwater contamination. The advection-dispersion equation (ADE) was considered to model the contaminant transport through the different media. Due to its inherent complexities, contaminant transport through the different domains was often difficult to model. To overcome it, the simple solution was to consider different velocities and dispersion for different domains. It was considered that the air zone was directly connected with the groundwater through a large water body. Initially, water body and aquifer had been considered contaminant free along with the flux type boundary condition at the semi-infinite part of the boundary. The model had been solved analytically using Laplace transformations. The current study demonstrates that depending upon the length of the medium the impact of contaminant would vary significantly. The air pollution source height had a direct impact on the contaminant concentration level in the aquifer aquitard system. The current study also illustrates that around 25% of air pollutants were induced in the groundwater. [ABSTRACT FROM AUTHOR]

We report the design, synthesis, and biological evaluation of a novel class of annulated indolizines as fluorescent probes. The compounds were generated through an eco-friendly, blue LED-induced domino reaction in ethyl acetate. A library of 24 coloured compounds exhibited tuneable emissions. One of the compounds (which we call DASS-fluor) proved to be an excellent polarity sensing probe. It is biocompatible, photostable, and detects specific types of lipid droplets (LDs in response to oleic acid, stress, and drug-induced autophagy in lungs and hepatic carcinoma cells). In comparison to Nile Red (a commercial probe), DASS-fluor can differentiate non-lysosomal LDs from lysosomal LDs and offers an advantage in precisely mapping drug-induced lipidosis caused by increased non-lysosomal LDs in cancerous cells. This unique probe could be a potential fluorescent marker for specific types of lipidosis induced by drugs. [ABSTRACT FROM AUTHOR]

This review explains various strategies for developing fluorescent probes to detect reactive carbonyl species (RCS). There are several mono and diacarbonyls among 30 varieties of reactive carbonyl species (RCSs) so far discovered, which play pivotal roles in pathological processes such as cancer, neurodegenerative diseases, cardiovascular disease, renal failure, and diabetes mellitus. These RCSs play essential roles in maintaining ion channel regulation, cellular signaling pathways, and metabolisms. Among RCSs, carbon monoxide (CO) is also utilized for its cardioprotective, anti‐inflammatory, and anti‐apoptotic effects. Fluorescence‐based non‐invasive optical tools have come out as one of the promising methods for analyzing the concentrations and co‐localizations of these small metabolites. There has been a tremendous eruption in developing fluorescent probes for selective detection of specific RCSs within cellular and aqueous environments due to their high sensitivity, high spatial and temporal resolution of fluorescence imaging. Fluorescence‐based sensing mechanisms such as intramolecular charge transfer (ICT), photoinduced electron transfer (PeT), excited‐state intramolecular proton transfer (ESIPT), and fluorescence resonance energy transfer (FRET) are described. In particular, probes for dicarbonyls such as methylglyoxal (MGO), malondialdehyde (MDA), along with monocarbonyls that include formaldehyde (FA), carbon monoxide (CO) and phosgene are discussed. One of the most exciting advances in this review is the summary of fluorescent probes of dicarbonyl compounds. [ABSTRACT FROM AUTHOR]

The human innate immune system eliminates invading pathogens through phagocytosis. The first step of this process is activating the nicotinamide adenine dinucleotide phosphate oxidase (Nox2) that utilizes NADPH to produce superoxide anion radicals and other reactive oxygen species (ROS). These ROS then alter the mitochondrial membrane potential and increase peroxide in the mitochondria. The peroxide reacts with myeloperoxidase (MPO) and chloride ions to produce pro-inflammatory oxidant hypochlorous acid (HOCl), which causes oxidative stress leading to cell death. The adverse effects of HOCl are highly associated with cardiovascular disease, neurodegenerative disorders, acute lung injuries, inflammatory diseases, and cancer. Therefore, mapping HOCl in the Nox2 pathway is crucial for an in-depth understanding of the innate immune system. Herein, we developed a unique pentacyclic pyridinium probe, PM-S, that exhibited efficient photoinduced electron transfer (PeT) with HOCl triggered methyl(phenyl)sulfane. PM-S showed several advantages, including better chemical stability, large Stokes shifts (>6258 cm−1), high sensitivity (∼50 nM) and specificity to mitochondria, compared to its parent pyrylium PY-S derivative. This probe is also efficient in studying the HOCl produced via the Nox2 pathway in HepG2 and HeLa cells. Analysis using a simple microplate reader and FACS analysis with various inhibitors and inducers supported the mechanistic understanding of Nox2, which can offer an advanced platform for monitoring the inflammatory process more efficiently. [ABSTRACT FROM AUTHOR]

A unique and highly water-soluble ICT-based fluorescent probe is developed for efficient detection and discrimination of reactive monocarbonyl formaldehyde (FA) from dicarbonyl methylglyoxal (MGO)/glyoxal (GO) by modulating the ICT process, which was confirmed by photophysical and TD-DFT analysis. The probe is applied in cellular imaging and quantifying FA in preserved food and MGO in manuka honey. [ABSTRACT FROM AUTHOR]

The first BODIPY library (BD) is prepared via a Knoevenagel-type condensation reaction and a highly selective glucagon sensor (Glucagon Yellow (BD-105)) is discovered by fluorescence image-based screening method. The results have shown the application of Glucagon Yellow as a glucagon imaging agent in live cells and tissues.

Abstract: Organelle‐targeted photosensitizers (PSs) having luminescence properties are potential theranostic agents for simultaneous luminescence imaging and photodynamic therapy. Herein, we report a water‐soluble luminescent cyclometalated IrIII complex, Ir‐Bp‐Ly, as a lysosome‐targeted theranostic probe. Ir‐Bp‐Ly exhibits exceptional photophysical properties, with good triplet‐state quantum yield (0.90), singlet oxygen generation quantum yield (0.71 at pH 4), and long lifetime (1.47 μs). Interestingly, Ir‐Bp‐Ly localizes mostly in lysosomes due to the presence of morpholine units, suggesting its potential use as a lyso‐tracker. Ir‐Bp‐Ly displays a notable PDT effect in C6 glioma cells, efficiently generating reactive oxygen species owing to close proximity between the energy levels of its triplet state and those of molecular oxygen (3O2). The mechanism of cell death has been studied through caspase‐3/7 and flow cytometry analyses, which clearly established the apoptotic pathway. [ABSTRACT FROM AUTHOR]

High altitude (HA) environments contain low levels of oxygen, which often cause nonspecific gastrointestinal (GI) disorders associated with acute mountain sickness (AMS). This study is conducted to investigate the alternation of microbial population and the physiological indices after being exposed to HA. Fecal and blood samples were collected from twelve army personnel in base-level environments in (Delhi, India) after acclimatization for seven days at 3505 m HA (Lah, India). Different bacterial groups, oxygen saturation level (SPO2), serum hemoglobin (Hb), hematocrit (HCT), blood urea, creatinine and microbial enzymes such as the α-amylase, proteinase, alkaline phosphatase and β-glucuronidase levels were all measured. It was observed that the total aerobic bacteria decreased significantly and the anaerobic and facultative anaerobic increased gradually in the intestines. Strict anaerobes including Bacteroidetes sp., Bifidobacterium sp., Lactobacillus sp. as well as pathogenic bacteria such as the Salmonella sp. exhibited positive growth. Various physiological parameters including serum hemoglobin, hematocrit, and urea-creatinine were also significantly changed. The microbial enzyme-activity also increased at HA. This confirms that the exposure to HA can change the intestinal microbial population affecting the microbial enzyme production possibly causing GI dysfunctions as a result of the decreased availability of oxygen. [ABSTRACT FROM AUTHOR]

Drug toxicity is a long-standing concern of modern medicine. A typical anti-pain/fever drug paracetamol often causes hepatotoxicity due to peroxynitrite ONOO−. Conventional blood tests fail to offer real-time unambiguous visualization of such hepatotoxicity in vivo. Here we report a luminescent approach to evaluate acute hepatotoxicity in vivo by chromophore-conjugated upconversion nanoparticles. Upon injection, these nanoprobes mainly accumulate in the liver and the luminescence of nanoparticles remains suppressed owing to energy transfer to the chromophore. ONOO− can readily bleach the chromophore and thus recover the luminescence, the presence of ONOO− in the liver leads to fast restoring of the near-infrared emission. Taking advantages of the high tissue-penetration capability of near-infrared excitation/emission, these nanoprobes achieve real-time monitoring of hepatotoxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs. [ABSTRACT FROM AUTHOR]

A diradical approach to obtain stable organic dyes with intense absorption around λ=1100 nm is reported. The para- and meta-quinodimethane-bridged BODIPY dimers BD-1 and BD-2 were synthesized and were found to have a small amount of diradical character. These molecules exhibited very intense absorption at λ=1088 nm ( ɛ=6.65×105 M−1 cm−1) and 1136 nm ( ɛ=6.44×105 M−1 cm−1), respectively, together with large two-photon-absorption cross-sections. Structural isomerization induced little variation in their diradical character but distinctive differences in their physical properties. Moreover, the compounds showed a selective fluorescence turn-on response in the presence of the hydroxyl radical but not with other reactive oxygen species. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform-dye-assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H2S is combined with UCNPs and results in a library of H2S sensors with responsive emission signals ranging from the visible to the near-infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H2S in vitro and in cells. Furthermore, H2S levels in blood can be detected using the developed nanoprobes. Hence the reported H2S sensing platform can serve as a powerful diagnostic tool to research H2S functions and to investigate H2S-related diseases. [ABSTRACT FROM AUTHOR]

A 241-membered cyanine-based library was constructed by the combinatorial chemistry strategy. Combined with high-throughput screening, we successfully discovered a novel fluorescent probe (CyC-M716) capable of identifying a subset of parallel G-quadruplexes with propeller loops stretching across three tetrad layers with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

A novel zwitterionic near-infrared (NIR) dye, ZWCC, has been designed and synthesized. It shows significantly enhanced photostability and chemical stability compared to the existing zwitterionic NIR dye. In addition, the feasibility of labeling ZWCC with biological ligands was investigated and used in live cell imaging applications. [ABSTRACT FROM AUTHOR]

The first fluorescent sensor for milk fat was developed. It exhibited a magnificent, yet selective turn-on feature towards fat molecules in a complicated milk matrix by a disaggregation-induced emission mechanism. Further construction of a handy fluorescence milk fat detector provided a convenient rapid tool to measure the fat amount quantitatively. This discovery may help enhance the milk quality control process. [ABSTRACT FROM AUTHOR]