Natural Clay-Modified Piezocatalytic Membrane for Efficient Removal of Coliform Bacteria from Wastewater.

In the modern era, water pollution, especially from industries, agricultural farms, and residential areas, is caused by the release of a large scale of heavy metals, organic pollutants, chemicals, etc., into the environment, posing a serious threat to aquatic ecosystems and nature. Moreover, untreated sewage waste discharged directly into nearby water bodies can cause various diseases to mankind due to the high load of fecal coliform bacteria. This work demonstrates the development of a biocompatible, cost-effective, highly robust, efficient, flexible, freestanding, and reusable membrane using naturally formed biocompatible kaolinite clay-doped poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for effective piezodynamic destruction of coliform bacteria. In this study, Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) have been used to evaluate the mechanical stimulus-responsive antibacterial efficacy of the nanocomposite membrane. The membrane can effectively eradicate nearly 99% viable E. coli and 97% E. faecalis within a span of 40 min under mechanical stimulation (soft ultrasound ∼15 kHz). To further understand the mechanism, an evaluation of reactive oxygen species and bacterial FESEM was performed. These studies revealed that bacterial cells suffered severe visible cell damage after 40 min of piezocatalysis, elucidating the fact that the synthesized membrane is capable of producing a superior piezodynamic antibacterial effect.

Recent progress in NIR-II fluorescence imaging-guided drug delivery for cancer theranostics.

Fluorescence imaging in the second near-infrared window (NIR-II) has become a prevalent choice owing to its appealing advantages like deep penetration depth, low autofluorescence, decent spatiotemporal resolution, and a high signal-to-background ratio. This would expedite the innovation of NIR-II imaging-guided drug delivery (IGDD) paradigms for the improvement of the prognosis of patients with tumors. This work systematically reviews the recent progress of such NIR-II IGDD-mediated cancer therapeutics and collectively brings its essence to the readers. Special care has been taken to assess their performances based on their design approach, such as enhancing their drug loading and triggering release, designing intrinsic and extrinsic fluorophores, and/ or overcoming biological barriers. Besides, the state-of-the-art NIR-II IGDD platforms for different therapies like chemo-, photodynamic, photothermal, chemodynamic, immuno-, ion channel, gas-therapies, and multiple functions such as stimulus-responsive imaging and therapy, and monitoring of drug release and therapeutic response, have been updated. In addition, for boosting theranostic outcomes and clinical translation, the innovation directions of NIR-II IGDD platforms are summarized, including renal-clearable, biodegradable, sub-cellular targeting, and/or afterglow, chemiluminescence, X-ray excitable NIR-IGDD, and even cell therapy. This review will propel new directions for safe and efficient NIR-II fluorescence-mediated anticancer drug delivery.

Nanoparticle-mediated stimulus-responsive antibacterial therapy.

The limitations associated with conventional antibacterial therapies and the subsequent amplification of multidrug-resistant (MDR) microorganisms have increased, necessitating the urgent development of innovative antibacterial techniques. Accordingly, nanoparticle-mediated therapeutics have emerged as potential candidates for antibacterial treatment due to their suitable dimensions, penetration capacity, and high efficiency in targeted drug delivery. However, although nanoparticle-based drug delivery systems have been demonstrated to be effective, they are limited by their overuse and unwanted side effects. Thus, to overcome these drawbacks, stimulus-responsive antibiotic delivery has been extended as a promising strategy for site-specific restricted drug exemption. Nano-formulations that are triggered by various stimuli, such as intrinsic, extrinsic, and bacterial stimuli, have been developed. Thus, by harnessing the physicochemical properties of various nanoparticles, the selective release of therapeutic cargoes can be achieved through the application of a variety of local stimuli such as light, sound, irradiation, pH, and magnetic field. In this review, we also highlight the progress and perspectives of stimulus-responsive combination therapy, with special emphasis on the eradication of MDR strains and biofilms. Hence, this review addresses the advancement and challenges in the applications of stimulus-responsive nanoparticles together with the various future prospects of this technique.

Piezo-responsive bismuth ferrite nanoparticle-mediated catalytic degradation of rhodamine B and pathogenic E. coli in aqueous medium and its extraction using external magnetic stimulation after successful treatment.

This work reports a solvothermal synthesis of ferromagnetic bismuth ferrite (BFO) nanoparticle and its piezo activity in the domain of catalytic degradation of carcinogenic and genotoxic rhodamine B (RhB) dye and pathogenic Escherichia coli bacteria as well. After synthesis and characterization, the structural and morphological features of the catalyst were further investigated using density functional theory (DFT), which enabled us to estimate the polarizability and many other important electrical properties of the synthesized material. The DFT study reveals remarkably high polarizability and dipole moment, which were utilized to validate the generation of piezo response by the synthesized material. Interestingly, we found enhanced piezo catalytic degradation efficiency (η ∼ 99%) along with a high rate constant (k ∼ 2.259 × 10-2 min-1), indicating a fast and efficient degradation process. In the case of pathogenic bacteria E. coli, the degradation efficacy was found to be ∼94%. Moreover, the extraction of this catalyst is quite simple. Due to its high remanent magnetization (retentivity ∼0.08 emu g-1), the catalyst can be extracted from the treated water sample by using external magnetic stimulation, making it a potential candidate for sustainable wastewater treatment.

Biocompatible Carbon Dot Decorated α-FeOOH Nanohybrid for an Effective Fluorometric Sensing of Cr (VI) in Wastewater and Living Cells.

This article reports the fluorometric detection of toxic hexavalent chromium Cr (VI)) in wastewater and Cr (VI) contaminated living cells using in-situ grown carbon quantum dots into the goethite (α-FeOOH) nano-matrix. The synthesized nano-hybrid shows enormous potential in determining the chromium contamination levels in various types of water samples. This selective fluorometric probe is enormously sensitive (LOD 81 nM) toward hexavalent chromium, which makes it a dedicated chromium sensor. Moreover, the sensing mechanism has been assessed using Stern-Volmer's equation and fluorescence lifetime experiments showing the simultaneous occurrence of photoinduced electron transfer and the inner filter effect. This chromium sensor has also been employed to assess the contamination level in real-life industrial wastewater. The performance of this probe in a real-life wastewater sample is quite commendable. Further, this biocompatible fluorometric probe has been used to demonstrate the in-vitro sensing of Cr (VI) in HeLa cells. The rapid detection mechanism of hexavalent chromium in living cells has been validated using theoretical docking simulations. Henceforth, this fluorometric sensor material could open new avenues not only in wastewater monitoring but also in biomedical applications.

Real-time sensitive detection of Cr (VI) in industrial wastewater and living cells using carbon dot decorated natural kyanite nanoparticles.

This article reports a facile strategy to detect hexavalent chromium (Cr (VI)) using a naturally formed mineral (kyanite) based fluorometric sensor. Nitrogenous carbon dots have been incorporated into natural kyanite (KYCD) nanoparticles causing a stable bright blue fluorescence compared to its pristine counterpart. This sensing probe structurally stabilizes and resists the agglomeration of carbon dots, thus retaining fluorescence quality for a longer period. The promising bright blue fluorescence has been utilized further to detect Cr (VI) in wastewater and living cells. Ease of synthesis, low cost, and stability of the system offers the benefit for large-scale production, which is convenient for industrial production the sensing probe. The sensor shows high selectivity and sensitivity (LOD and LOQ of 0.11 µM and 0.36 µM respectively in case of linear fitting, whereas 0.26 µM and 0.88 µM respectively for full range plot) towards hexavalent chromium in presence of other interfering elements. A detailed study of photoinduced electron transfer (PET) mediated rapid 'turn off' sensing mechanism was carried out using Time-Dependent Density functional (TDDFT) calculations. The sensing efficacy of the probe remains unaltered under a wide range of pH and can be effective in various water types. Onsite sampling and probing of Cr (VI) in tannery wastewater has been performed to validate its real-life efficiency that yields excellent results. The sensor can effectively detect chromium at a cellular level (HeLa cells) in a similar way as the bright blue fluorescence diminishes in presence of the quenching ion. Experimental in vitro studies along with theoretical docking analysis has been conducted to substantiate such issues and a higher possibility of fluorophore binding was found for Isoleucine (2.9 Å), Serine (2.96 Å), and Glycine (3.16 Å). This biocompatible sensor rapidly senses hexavalent chromium in living cells, which makes this efficient probe a true heavy metal-induced carcinogen sensor.

Recent advances in piezocatalytic polymer nanocomposites for wastewater remediation.

Among several forms of water pollutants, common pesticides, herbicides, organic dyes and heavy metals present serious and persistent threats to human health due to their severe toxicity. Recently, piezocatalysis based removal of pollutants has become a promising field of research to combat such pollutions by virtue of the piezoelectric effect. In reality, piezoelectric materials can produce electron-hole separation upon external vibration, which greatly enhances the production of various reactive oxygen species (ROS) and further increases the pollutant degradation rate. Piezocatalysis does not alter the quality or composition of water, like several other conventional techniques (adsorption and photocatalysis), which makes this technique non-invasive. The simplicity and tremendously high efficacy of piezocatalysis have attracted researchers worldwide and thus various functional materials are employed for piezocatalytic wastewater remediation. In this frontier, we highlight and demonstrate recent developments on polymer based piezocatalytic nanocomposites to treat industrial wastewater in a facile manner that holds strong potential to be translated into a clean and green technology.

Flexible and reusable carbon dot decorated natural microcline membrane: a futuristic probe for multiple heavy metal induced carcinogen detection.

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr6+) and trivalent iron (Fe3+) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414 nm and "turn-off" response was observed specifically for Fe3+ at 489 nm. A prominent red shift (530 nm) of the fluorescence maxima takes place when it comes to Cr6+. Figures of merit, such as LOD (8.7 µM for Cr6+ and 18.4 µM for Fe3+) and LOQ (29.1 µM for Cr6+ and 61.6 µM for Fe3+), were evaluated from the linear range (0-60 µM for Cr6+ and 0-30 µM for Fe3+) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr6+ and Fe3+. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.

In Situ-Grown Cdot-Wrapped Boehmite Nanoparticles for Cr(VI) Sensing in Wastewater and a Theoretical Probe for Chromium-Induced Carcinogen Detection.

In modern society, massive industrialization escalates environmental degradation by liberating various contaminants into the environment. Hexavalent chromium is a heavy metal that is being discharged from tannery and other industries, resulting in various carcinogenic diseases. This study reports a carbon dot (cdot)-based fluorometric probe for detecting hexavalent chromium in water. This is the very first time that cdots are tailored over the boehmite nanoparticle's surface using an in situ approach. Validation of formation of the nanocomposite has been discussed in detail employing the Rietveld refinement-based X-ray crystallography method. Vibrational spectroscopy and electron microscopy of the sample authenticate the nucleation process and the growth mechanism. The Stern-Volmer approach and time-resolved fluorescence measurements justify the sensitivity of the sensor (∼58 nM), and selectivity is analyzed by exposing the material to different ionic environments. Density functional theory (DFT) is applied herein to analyze the origin of fluorescence and the sensing mechanism of the probe, which shows that photoinduced electron transfer is responsible for the turn-off-based sensing of Cr(VI). The molecular docking simulation is carried out to ensure the binding of cdots to the binding pocket of the glutathione enzyme, which is responsible for treating reactive oxygen species-mediated DNA damage due to elements such as hexavalent chromium. Time-dependent density functional calculations show that the fluorometric probe is capable of detecting Cr(VI) in living cells making it an early stage chromium-mediated carcinogen detector.

Nitrogenous carbon dot decorated natural microcline: an ameliorative dual fluorometric probe for Fe3+ and Cr6+ detection.

In the modern era, the escalation of heavy metal discharges, especially from the industrial sector, is causing an enormous threat to nature. This article explores the dual sensing of heavy metals (Cr6+ and Fe3+) using a naturally formed microcline based sensor. A nano-sized microcline (M) was obtained via a facile top-down synthesis. In order to enhance the fluorescence property of the material, nitrogenous carbon-dots were loaded into the porous structure of the microcline (MCD) causing a bright blue fluorescence with remarkable stability. Detailed analysis of the composition and structure of the natural nano-sensor was carried out using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and BET analysis. This sensor material is highly selective towards Cr6+ and Fe3+, demonstrating a "turn-off" response in aqueous Fe3+ and a radical red shift of the fluorescence maxima for aqueous Cr6+. Density functional studies suggest that photoinduced electron transfer (PET) based quenching of fluorescence is responsible for these types of fluorescence alteration mechanisms. Efficient sensing of both Cr6+ and Fe3+ in various real-life water samples along with a real wastewater sample is also reported herein. A few studies have previously reported on efficient, natural material-based sensors, but they lack real-life applications due to their complicated synthesis and restricted functionalities. This work manages to overcome those drawbacks in its own fashion, providing a tremendously selective and sensitive (4 µM for Cr6+ and 19 µM for Fe3+) dual fluorescent probe.

Development of a Cu(ii) doped boehmite based multifunctional sensor for detection and removal of Cr(vi) from wastewater and conversion of Cr(vi) into an energy harvesting source.

This article reports a copper doped boehmite (CBH) based nano-material which is capable of detecting and removing hexavalent chromium simultaneously. Basic characterization has been performed to determine its phase purity, particle size (∼20 nm), morphology and surface properties (surface area 15.29 m2 g-1 and pore diameter 3.9 nm) by using some basic characterization tools. The Rietveld refinement method has been adopted to analyze the microstructural details of the synthesized nanostructure. Photoinduced electron transfer (PET) based quenching of fluorescence is mainly responsible for chromium sensing in this case. This nanosensor is exceptionally sensitive (limit of detection ∼ 6.24 µM) and merely selective towards hexavalent chromium ions. Industrial wastewater samples have also been used here to demonstrate the real life applicability of this material, which shows the same trend. This fluoro-sensor gains its multi-functionality when it comes to the adsorption based removal of Cr(vi) from wastewater. The synthesized material shows a remarkably high adsorption rate (∼85% in just 5 minutes) due to its sponge-like porous structure. Adsorption of hexavalent chromium from wastewater enhances the dielectric constant of this material significantly (∼7.93 times). Ionic polarization-dependent enhancement of the dielectric constant resulting from industrial wastewater treatment is a quite unmarked approach. Very low tangent loss with augmented dielectric permittivity makes this nano-material desirable for energy harvesting applications. Previously many articles have reported the sensing and removal of various industrial effluents. Keeping this in mind, this work has been designed and, apart from sensing and removal, it provides a new insight into energy harvesting from wastewater.

Gd(III)-Doped Boehmite Nanoparticle: An Emergent Material for the Fluorescent Sensing of Cr(VI) in Wastewater and Live Cells.

This article reports the effect of Gd(III) doping on the structure, microstructure, and optical properties of boehmite nanoparticles. The bright-blue fluorescence along with a long lifetime makes our material an efficient candidate for optical applications. Our material particularly targets and eliminates hexavalent chromium ions (Cr(VI)) from aqueous media, which turns it into a multifunctional fluorescent nanosensor (MFNS). The development of an efficient hexavalent chromium ion (Cr(VI)) sensor to detect and quantify Cr(VI) ions is still a serious issue worldwide. Thus, this work will be very beneficial for various environmental applications. No such work has been reported so far which includes cost-effective and biocompatible boehmite nanoparticles in this field. Detailed synthesis and characterization procedures for the MFNS have been incorporated here. The biocompatibility of the MFNS has also been studied rigorously by performing cell survivability assay (MTT) and cellular morphology assessments. Our extensive research confirmed that the "turn-off" sensing mechanism of this sensor material is based on a collisional quenching model which initiates the photoinduced electron transfer (PET) process. High selectivity and sensitivity (∼1.05 × 10-5 M) of the MFNS toward hexavalent chromium ions even in real life wastewater samples have been confirmed, which makes this fluorescent probe a potential candidate for new age imaging and sensing technologies.

Nanoparticle Size-Dependent Antibacterial Activities in Natural Minerals.

The size-dependent antibacterial activities of three minerals namely; alkali feldspar, calcite and stibnite are reported as examined individually against Escherichia coli and Staphylococcus aureus by evaluating minimum inhibitory concentration (MIC) with colony counting method, along with cell survivability assay (MTT). Each of these minerals were grinded into fine-size fractions-S1 (bulk), S2 (ball milled) and S3 (nanosized) and spectroscopically characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-Vis) spectroscopy. Antibacterial activity was found to be highest in the nanosized (S3) minerals. Interaction between bacteria and nanosized mineral samples produce intracellular reactive oxygen species (ROS), which might cause higher bacterial mortality. The penetration due to nano-dimension is another significant observation as evidenced by bacterial FESEM micrographs. The current findings thus provide a pathway for future research on antibacterial products retrievable from widely available geological materials. The size dependant antibacterial activity of naturally formed minerals is a new insight to reduce bacterial contamination in living systems.

An In Vivo Study for Targeted Delivery of Curcumin in Human Triple Negative Breast Carcinoma Cells Using Biocompatible PLGA Microspheres Conjugated with Folic Acid.

Among the different types of polymeric vehicles, (PLGA) is biodegradable and has emerged as promising tool for the delivery of cancer therapeutics. The salient features of PLGA micro carriers include prolonged circulation time, increased tumor localization and biodegradability and effectiveness of the therapeutics. We have synthesized PLGA microspheres where curcumin can be loaded and thereby increases its bioavailability. The cytotoxicity of curcumin (PLGA@CCM) microspheres was evaluated on triple negative breast cancer (TNBC) cell lines. They were found to induce apoptosis by perturbing the mitochondrial membrane potential. PLGA@CCM@FA induces apoptosis in human triple negative breast cancer cells by up-regulating Cleaved caspase-3 and down regutes p-AKT. The in-vivo study in BALB/C mice model exhibited more tumor regression in case of PLGA@CCM@FA microspheres. Our results suggests that these microspheres can be an effective vehicle for delivery of hydrophobic drugs to the folate over expressed cancer cells.

Folic acid conjugated curcumin loaded biopolymeric gum acacia microsphere for triple negative breast cancer therapy in invitro and invivo model.

Among the different types of biomaterials, natural excipients gum acacia (GA) is economic and has the potential for controlled drug delivery. We have synthesized GA microspheres by co-precipitation method and characterized them by XRD, FESEM, 1H NMR, FTIR, UV visible spectra and DLS. Despite its potential anti-cancer activity, solubility of curcumin is very low rendering its limit in application. We have used GA microspheres where curcumin can be loaded comfortably and thereby increases its bioavailability. The cytotoxicity of curcumin encapsulated GA microspheres was evaluated on triple negative breast cancer cell lines. They were found to induce apoptosis by perturbing the mitochondrial membrane potential. Folic acid was conjugated to curcumin encapsulated GA microspheres, for delivering it specifically to the cancer cells. The in-vivo study in BALB/C mice model exhibited more tumor regression in case of folic acid targeted curcumin encapsulated GA microsphere. Our results implicates that these microspheres can be an effective therapeutic agent to folate receptors over expressing cancer cells.