This review focuses on the self-aggregation properties of different drugs, as well as on their interaction with anionic, cationic, and gemini surfactants. The interaction of drugs with surfactants has been reviewed concerning conductivity, surface tension, viscosity, density, and UV-Vis spectrophotometric measurements, and their relation with critical micelle concentration (CMC), cloud point, and binding constant. The conductivity measurement technique is used for the micellization of ionic surfactants. Cloud point studies can be used for the non-ionic, and also for certain ionic surfactants. Usually, surface tension studies are mostly employed for non-ionic surfactants. The degree of dissociation that is determined is used to evaluate thermodynamic parameters of micellization at various temperatures. The effect of external parameters like temperature, salt, solvent, pH, etc., is discussed for thermodynamics parameters using recent experimental works on drug-surfactant interactions. Consequences of drug–surfactant interaction, condition of drugs during interaction with surfactants, and applications of drug–surfactant interaction are being generalized which reflects current and future potential uses of drug–surfactant interactions.

Herein we have discussed such important modified rhodamine compounds which have been used as chemosensors for the last 7–8 years. This review covered some chemosensors for the detection of metal ions like Al(III), Cu(II), Hg(II), Co(II), Fe(III), Au(III), Cr(III), and some anion like CN⁻. The selectivity, sensitivity, photophysical properties (i.e., UV–Vis spectral studies, fluorescence studies giving special emphasis to absorption wavelength in UV–Vis spectra and excitation and emission wavelength in fluorescence spectra), binding affinity, the limit of detection, and the application of those chemosensors are described clearly. Here we have also discussed some functionalized rhodamine-based chemosensors that emit in the near-infrared region (NIR) and can target lysosomes and detect lysosomal pH. Their versatile applicability in the medicinal ground is also delineated. We have focused on the photophysical properties of spirolactam rhodamine photoswitches and applications in single-molecule localization microscopy and volumetric 3D light photoactivable dye displays. The real-time detection of radical intermediates has also been exemplified. Graphical Abstract

The reservoir at the Tilaiya Dam constructed on the Barakar river is one of the most important freshwater resources in the Koderma District in the state of Jharkhand in India. Its water is used primarily in agriculture, pisiculture, industry, regional thermal power plant, and various domestic errands viz. cooking, washing, and drinking. The reservoir also supports a wide variety of flora, fauna, and birds. This work reports the variation in seasonal water quality (pH, turbidity, DO, TDS, electrical conductivity, total hardness, iron, chloride, calcium, magnesium, alkalinity, phosphate, sulfate, fluoride, total bacterial count, and fecal coliform count) trends over a 4-year long period (July 2013–July 2017). Conspicuous dilution effect on water quality was observed during and just after the monsoon season while concentrations of TDS, electrical conductivity, iron, chloride, calcium, magnesium, phosphate, sulfate, and fluoride increased during summer. Principal Component Analysis/Factor Analysis (PCA/FA) identified three factors in the data structure, explaining about 71.5–77.9% of total variance in dataset. Run-off from catchment areas was one of the major factors that influenced water quality during the monsoon seasons. The t test indicated that except between summer and post-monsoon in 2013 and 2014, seasonal DO values had statistically significant difference. Also, turbidity in summer, post-monsoon and winter seasons had statistically significant differences while total hardness (TH) was statistically different in summer over winter but not in summer over post-monsoon. On the other hand, TDS did not have statistically significant seasonal shifts. Water quality index (WQI), pollution index (PI), comprehensive pollution index (CPI), computed over the study years revealed that water quality of the reservoir could be categorized as ‘Good’ but is gradually deteriorating. This calls for greater attention and proper management of the Tilaiya reservoir in the interest of environmental and regional sustainability of Koderma.

Groundwater quality in rural Chandwara block in Jharkhand State in India is crucial to human livelihood in the region. A study undertaken to examine groundwater quality and consumption patterns in the region revealed that average water consumption per family and per capita were 200–517 and 19.7–47 L per day, respectively, while per capita potable water consumption was 1.2‒4.37 L per day. Groundwater samples were collected primarily from tube-wells and a few from dug-wells (n = 143) in the block during post-monsoon season of 2018–2019 (October 2018 to March 2019). Water quality parameters like Fe, TDS, Total hardness, Ca and turbidity were above the permissible limits of Bureau of Indian Standards (BIS) and WHO in 68%, 36%, 39%, 58% and 15.4% of groundwater samples, respectively. Most of the samples (67.9%) belonged to Ca–Mg–HCO₃ class while a few (28.6%) were Ca-Mg-SO₄-Cl type and the rest (3.6%) were in Ca–Mg–Cl class. As per Gibbs Plot, most samples belonged to the rock weathering region, implying contribution of rock forming minerals to groundwater chemistry. Factor analysis revealed that water quality was controlled by four principal factors to the extents of 43.3, 13.5, 10.9 and 7.3%, respectively, making a cumulative contribution of about 75%. Parameter loading in Factor 1 strongly indicated to various salts dissolving in groundwater from the rocks while Factor 2 was loaded by Fe coming from Fe-bearing rocks and turbidity that is positively influenced by the former. Factor 3 is loaded by pH and alkalinity, pointing to the role of carbonates contributed by the rocks while factor 4, which is loaded by F⁻ and Na, indicates to F⁻incorporation in water from NaF-bearing rocks.

Hydrochemical properties of groundwater (n = 32) collected from eight Gram Panchayats (GP) in Kushmandi Block of South Dinajpur District in West Bengal, India and human health risk posed by groundwater fluoride (F⁻) and iron (Fe) are reported. About 18% and 28.7% of the collected water samples exceeded the permissible limits for F⁻ and Fe, respectively, as per prescribed potable water quality standards of WHO and Bureau of Indian Standards. Total Dissolved Solid in groundwater never exceeded the acceptable limit of 500 mg l ⁻¹ (maximum value was 301.6 mg l ⁻¹) while NO₃- ranged from near zero to 17.8 mg l⁻¹, never exceeding the safe limit of 45 mg l⁻¹. Hydrogeochemical analyses revealed the dominance of Ca/Na-bicarbonate type water throughout the Block and indicated that fluorite (CaF₂) could be the most prominent source of F⁻ in groundwater. Non-carcinogenic health risk index due to exposure to F⁻ was more than unity in infants, children and adults in the order of HQ_Children>HQ_Infant>HQ_Adult. Sensitivity analysis to ascertain non-carcinogenic human health risk of F⁻ through multi-exposure pathways undertaken by Monte Carlo (MC) simulation (Oracle Crystal Ball, version 11.1.2.4.850) indicated that concentration of F⁻ and Fe (Ci), their ingestion rate (IR), and exposure duration (ED) were the most influential governing factors behind non-carcinogenic health risks posed by F⁻ and Fe consumption. Groundwater was rated as having ‘Low’ irrigation water quality (Sodium Adsorption Ratio, SAR <10 and Residual Sodium Carbonate, RSC of 0.41–2.88). Other important parameters of irrigation water quality, such as electrical conductivity (maximum 409 μS cm⁻¹) and chloride (maximum 30.8 mg l⁻¹), were also well within the recommended safe limits.