Carbon Dots: Synthesis, Characterizations, and Recent Advancements in Biomedical, Optoelectronics, Sensing, and Catalysis Applications.

Carbon nanodots (CNDs), a fascinating carbon-based nanomaterial (typical size 2-10 nm) owing to their superior optical properties, high biocompatibility, and cell penetrability, have tremendous applications in different interdisciplinary fields. Here, in this Review, we first explore the superiority of CNDs over other nanomaterials in the biomedical, optoelectronics, analytical sensing, and photocatalysis domains. Beginning with synthesis, characterization, and purification techniques, we even address fundamental questions surrounding CNDs such as emission origin and excitation-dependent behavior. Then we explore recent advancements in their applications, focusing on biological/biomedical uses like specific organelle bioimaging, drug/gene delivery, biosensing, and photothermal therapy. In optoelectronics, we cover CND-based solar cells, perovskite solar cells, and their role in LEDs and WLEDs. Analytical sensing applications include the detection of metals, hazardous chemicals, and proteins. In catalysis, we examine roles in photocatalysis, CO2 reduction, water splitting, stereospecific synthesis, and pollutant degradation. With this Review, we intend to further spark interest in CNDs and CND-based composites by highlighting their many benefits across a wide range of applications.

Design, synthesis and in silico evaluation of newer 1,4-dihydropyridine based amlodipine bio-isosteres as promising antihypertensive agents.

Hypertension remains a major global health concern, prompting ongoing research into innovative therapeutic approaches. This research encompasses the strategic design, synthesis, and computational assessment of a novel series of 1,4-dihydropyridine based scaffolds with the objective of developing promising antihypertensive agents as viable alternatives to the well-established dihydropyridine based drugs such as amlodipine, felodipine, nicardipine, etc. The crystal structure of the lead compound determined using X-ray crystallography offers crucial insights into its 3D-conformation and intermolecular interactions. In silico molecular docking experiments conducted against the calcium channel responsible for blood pressure regulation revealed superior docking scores for all the bioisosteres P1-P14 than the standard amlodipine, indicating their potential for enhanced therapeutic efficacy. Extensive ADMET profiling and structure-activity relationship (SAR) elucidated favourable pharmacokinetic properties and essential structural modifications influencing antihypertensive effectiveness. Specifically, P6-P10, P12 and P14 hybrids were found in accordance with Lipinski rules and exhibited druglikeliness attributes, involving high GI absorption and no BBB permeance. In particular, P7 was found to be crystalline in nature having the highest binding affinity with the concerned calcium channels with excellent ADMET profile. The findings highlight the significance of the presence of triazole tethered aryl/heteroaryl ring in the synthesized hybrids, providing a foundation for further preclinical and clinical translation as antihypertensive medications.

A Review of Electrochemical Techniques for Corrosion Monitoring - Fundamentals and Research Updates.

Interculturally, corrosion has been counted as one of the most expensive factors toward the retrogression of concrete and metallic structures resulting in huge monetary losses and unanticipated loss of life. To a large extent, corrosion-related catastrophes can be avoided by having the ability to monitor corrosion before structural integrity is jeopardized. This paper critically reviews the various accustomed electrochemical techniques utilized for corrosion monitoring in terms of their definition, timeline, experimental set-up, advantages, and shortcomings. Additionally, literature exploiting these techniques as their corrosion detection technique has been focused on here. Furthermore, a comparison between recently reported methods has been made to provide better insights into the research progress in this arena.

A rhodamine based fluorescent and colorimetric chemosensor for the detection of Cr3+ ions and its utility in a molecular logic gate.

A new rhodamine based fluorescent and colorimetric chemosensor S1 was synthesized for the selective recognition of Cr3+, a trivalent metal ion. The interaction of S1 toward different metal ions has been studied via fluorescence and UV-visible spectroscopy. The studies revealed that the fluorescence and colorimetric changes of chemosensor S1 are prominent for Cr3+ over other competitive metal ions. Moreover, the chemosensor S1 exhibits 1 : 1 complex formation with Cr3+ as apparent from the Job's plot and the Benesi-Hildebrand (B-H) plot. Density functional theory (DFT) studies also revealed that the Cr3+ ion is coordinated to three atoms of S1, which validates the formation of a complex between S1 and Cr3+. The limit of detection (LOD) of chemosensor S1 for Cr3+ was 0.21 µM. Furthermore, to explore the recyclability of S1, ethylenediaminetetraacetic acid (EDTA) was added to the S1-Cr3+ solution. On the addition of EDTA to the solution of S1-Cr3+, the reversibility of the complex was observed, and a colorimetric variation was also observed on the addition of Cr3+ and EDTA to S1 which mimics the "INHIBIT "molecular logic gate. Chemosensor S1 also demonstrated practical utility through detection of Cr3+ in the solid state.

"Optimization and evaluation of quality characteristics of traditional Indian snack (baked balls) made by using pumpkin peel powder".

The baked balls (traditional Indian snack litti) were formulated along with the standardization and optimization of different ingredients and recipe. The optimization was done by using response surface methodology. Box behnken model was selected for the optimization in which wheat flour (40-80%), roasted bengal gram flour (10-50%), and pumpkin peel powder (2.5-15%) were selected as an independent factor for the standardization of baked balls recipe against the dependent factors including sensory attributes (colour and texture), moisture content and water activity. The proximate analysis of optimized baked balls resulted in energy, carbohydrate, protein, fat, dietary fibre, calcium, iron, and zinc value as 310 kcal, 55.6 g/100 g, 13.78 g/100 g, 2.73 g/100 g, 40.18 mg/100 g, 4.57 mg/100 g and 2.97 mg/100 g respectively. Additionally, carotenoid content of control and optimized baked balls was found to be 284 µg/100 g and 838.93 µg/100 g whereas the ascorbic acid content was observed as 1.84 mg/100 g and 5.82 mg/100 g respectively. It showed a significant increase in nutritional parameters when compared with control (wheat flour) baked balls. This study also evidenced that pumpkin peel powder can be used as a food supplement for various nutritional components.

Stability of carbon quantum dots: a critical review.

Carbon quantum dots (CQDs) are fluorescent carbon nanomaterials with unique optical and structural properties that have drawn extensive attention from researchers in the past few decades. Environmental friendliness, biocompatibility and cost effectiveness of CQDs have made them very renowned in countless applications including solar cells, white light-emitting diodes, bio-imaging, chemical sensing, drug delivery, environmental monitoring, electrocatalysis, photocatalysis and other related areas. This review is explicitly dedicated to the stability of CQDs under different ambient conditions. Stability of CQDs is very important for every possible application and no review has been put forth to date that emphasises it, to the best of our knowledge. This review's primary goal is to make the readers cognizant of the importance of stability, ways to assess it, factors that affect it and proposed ways to enhance the stability for making CQDs suitable for commercial applications.

A pyridine dicarboxylate based hydrazone Schiff base for reversible colorimetric recognition of Ni2+ and PPi.

A pyridine dicarboxylate Schiff-base DAS was synthesized for cascade colorimetric recognition of Ni2+ and PPi. The selectivity and sensitivity of chemosensor DAS was investigated through colorimetric and UV-vis studies in MeOH-PBS (5 : 1, v/v, pH = 7.4). The chemosensor formed a 2 : 1 complex with Ni2+ metal ions with a binding constant of Ka = 3.07 × 103 M-2. Besides, a plausible sensing mechanism is confirmed by single crystal X-ray diffraction (SC-XRD), Job's plot and Benesi-Hildebrand plot (B-H plot) experiments. Furthermore, the DAS-Ni2+ ensemble formed 'in situ' was used to selectively recognise PPi. The limit of detection (LOD) of DAS for Ni2+ was found to be 0.14 µM and that of the DAS-Ni2+ ensemble for PPi was found to be 0.33 µM. Also, the potential of the chemosensor has been applied for solid state detection of Ni2+ as well as to mimic the 'INHIBIT' logic gate on the addition of Ni2+ ions and PPi.

In vitro and Bioimaging Studies of Mesoporous Silica Nanocomposites Encapsulated Iron-oxide and Loaded Doxorubicin Drug (DOX/IO@Silica) as Magnetically Guided Drug Delivery System.

BACKGROUND: In recent years, the delivery of drugs by nanocomposites has emerged as an exciting field of research for bio-imaging tools and targeted cancer treatment. The large surface area and porous volume of mesoporous silica nanocomposites (MSN's) have gained a lot of interest for their application in the delivery of drugs and the magnetic properties of iron oxide (IO) nanocomposites play a key role in the targeted delivery system. METHODS: In this study, mesoporous silica encapsulated IO nanocomposites loaded with doxorubicin (DOX) were synthesized for the magnetically guided delivery of anticancer drugs. The synthesis of IO nanocomposites was done through the precipitation method, and then silica encapsulation and drug loading were done by the StÖber method. RESULTS: The magnetically driven delivery of the drug is produced by the encapsulation of magnetically active IO in the mesoporous silica shell. The controlled release of DOX is possible because of the MSN's. TEM images show that the nanocomposites have a spherical morphology and average diameter in the range of 120 nm. Power-XRD data confirm the crystalline nature of nanocomposites. The strong absorption peak was observed in UV-Visible spectroscopy at 490 nm and quenching in fluorescence spectra confirms the encapsulation of DOX in the mesoporous silica shell. VSM data showed the magnetic nature of nanocomposites, with large magnetic susceptibility (74.88 emu/g). The use of DOX/IO@Silica nanocomposites as a sustainable drug release and targeted drug delivery vehicle has been reported here. The pH dependent release of DOX was studied and significant release was observed at lower pH. In-vitro cell viability assay and fluorescence imaging assay have demonstrated that these nanocomposites show significant dose-dependent toxicity to cancer cells in the presence of a magnetic field. CONCLUSION: In-vitro studies via the MTT assay showed that these synthesized nanocomposites in culture are non-toxic to healthy cells compared to DOX-induced cytotoxicity due its controlled release and can be further strengthened by magnetic guidance. Therefore, due to its optical properties and potential for guided delivery of drug to the targeted site, these nanocomposites are ideal as an anticancer agent and bio-imaging prob.

Trend of malaria incidences and its association with rainfall in Kalahandi District of Odisha, India.

In Odisha, Kalahandi is one of the most exposed and vulnerable districts to malaria incidences due to its poor socioeconomic condition and extreme climate. The study aimed to explore the temporal characteristics of malaria incidences in Kalahandi and to identify its relationship with rainfall for the period from 2011 to 2018. Out of the total blood films examined, 8.84% were found positive in Kalahandi between 2011 and 2018. Plasmodium falciparum is the most dominant species accounted 88.3% of the total cases. Very high mean annual parasitic index (API) >15 is recorded throughout the study years. The highest incidences are recorded in the monsoon season followed by postmonsoon. The correlation value of the annual blood examination rate with P. falciparum, Plasmodium vivax, and API has shown a very high positive correlation. Rainfall shows a (+) correlation with malaria incidences in the cold (0.47) and hot seasons (0.01) and (-) correlation in the monsoon (-0.54) and postmonsoon season (-0.54).

Extracellular Electron Transfer by Pseudomonas aeruginosa in Biocorrosion: A Review.

Microorganisms with extracellular electron transfer (EET) capability have gained significant attention for their different biotechnological applications, like biosensors, bioremediation, and microbial fuel cells. Current research affirmed that microbial EET potentially promotes corrosion of iron structures, termed microbiologically influenced corrosion (MIC). The sulfate-reducing (SRB) and nitrate-reducing (NRB) bacteria are the most investigated among the different MIC-promoting bacteria. Unlike extensively studied SRB corrosion, NRB corrosion has received less attention from researchers. Hence, this review focuses on EET by Pseudomonas aeruginosa, a pervasive bacterium competent for developing biofilms in marine habitats and oil pipelines. A comprehensive discussion on the fundamentals of EET mechanisms in MIC is provided first. After that, the review offers state-of-the-art insights into the latest research on the EET-assisted MIC by Pseudomonas aeruginosa. The role of electron transfer mediators has also been discussed to understand the mechanisms involved in a better way. This review will be beneficial to open up new opportunities for developing strategies for combating biocorrosion.

Multiple phenyl ring appended Re-based complexes for strong visible light absorption and DNA binding.

A series of facial-Re(CO)3-based acyclic complexes (1-3) possessing N∩O bis-chelating ligands and a triphenylphosphine oxide donor was synthesized and characterized. The most interesting structural feature of these complexes is that both the coordinated ligands are functionalized with external phenyl rings. Single crystal X-ray diffraction analysis confirms that each molecule demonstrates a variety of intermolecular supramolecular interactions via the external phenyl rings. All the complexes displayed strong absorption (ε = 14 000-40 000 M-1 cm-1) over wide visible region (400-600 nm). Due to the interesting structural and photophysical properties of the complexes, a satisfactory DNA binding ability was observed. The binding of the complexes with DNA grooves was confirmed by a significant increase in the absorption intensities of the complexes in the visible region, absorption enhancement of DNA and circular dichroism.

Silver Nanoprism for Selective and Sensitive Detection of Hg+2 Ions.

In this article, we propose high-performance colorimetric detection of Hg+2 using silver nanoprisms. The spherical and triangular AgNPs were synthesized using varied concentration of NaBH4. Pristine AgNPs without any further modification were used for the detection of various metal ions including Hg2+, Pb2+, Cl-, Cd2+, Co2+, Cu2+, Ba2+, Pb2+, Cr3+, Cr2O2-7 , Fe2+, Fe3+ etc. AgNPs were not only selective in detecting the ions of Cl- and Hg+2 ions but also highly sensitive. Minimum detection limit was observed to be as low as 10-7 ppm for both Hg+2 and Cl-. Water samples collected from various locations detected for the presence of various heavy metals. Silver nanoprisms owing to their surface plasmon resonance exhibit highly selective tendency towards detection against Hg+2.

Comparative Investigation of Corrosion-Mitigating Behavior of Thiadiazole-Derived Bis-Schiff Bases for Mild Steel in Acid Medium: Experimental, Theoretical, and Surface Study.

In the present study, comparative analyses of corrosion inhibition property of few thiadiazole-derived bis-Schiff bases for mild steel in 1 M HCl were done. Various electrochemical experiments (electrochemical impedance spectroscopy and potentiodynamic polarization), as well as weight loss experiments, were employed to study the anticorrosion activity of bis-Schiff bases as inhibitors. The highest inhibition efficiency was obtained at an optimum concentration of 125 ppm for all inhibitors. Potentiodynamic polarization studies explain the mixed type but predominantly the cathodic nature of all inhibitors. The Langmuir adsorption isotherm was used to describe the mechanism of adsorption. The change in the value of activation energy on the addition of inhibitors reflects the mixed mode of interaction between the inhibitor and metallic surface. Scanning electron microscopy with energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses confirmed the adsorption of bis-Schiff bases on the metal surface and thereby shielding from corrosion. Besides, the relevance between inhibition efficiency and the molecular structure of an inhibitor was theoretically examined via quantum chemical calculations and molecular dynamics simulations. All the results show consistent agreement with each other.

Relation of degree of substitution and metal protecting ability of cinnamaldehyde modified chitosan.

Considering the advancements in the applications of biopolymers such as Chitosan due to its biocompatibility, biodegradability and non-toxic properties, five different Chitosan cinnamaldehyde Schiff bases (Chi-Cn1-5) using chitosan and cinnamaldehyde as monomer units were synthesized by varying the degree of substitution. Further, anti-corrosion property of all these biopolymers against corrosion of mild steel was studied in 0.5 M H2SO4 by gravimetric and electrochemical methods. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM), scanning electrochemical microscopy (SECM) and X-ray photoelectron spectroscopy (XPS) were utilized to affirm the adsorption of studied biopolymers at the metal/electrolyte interface by inhibiting mild steel (MS) corrosion. The shift (<85 mV) in the value of corrosion potential by the presence of biopolymers affirmed their mixed-type nature of inhibition. The results depicted that Chi-Cn5 performs best against corrosion of mild steel in acid medium among all other biopolymers due to its maximum degree of substitution.

2-Hydroxy-N'-((Thiophene-2-yl)methylene)benzohydrazide: Ultrasound-Assisted Synthesis and Corrosion Inhibition Study.

2-Hydroxy-N'-((thiophene-2-yl)methylene)benzohydrazide (HTMBH) was synthesized by conventional method as well as by ultrasonication (US). The ultrasound-assisted synthesis of HTMBH was found to have good yield and be more eco-friendly compared to the conventional method of synthesis. The synthesized compound HTMBH was characterized by Fourier transform infrared, 1H NMR, and CHN analyses. The corrosion inhibition behavior of HTMBH was investigated using gravimetric and electrochemical methods in 0.5 M H2SO4. The thermodynamic adsorption parameters revealed that HTMBH was adsorbed on the mild steel surface in both ways, physically and chemically, although physisorption is predominant. The study of activation parameters revealed that it is the increase in activation energy that is a prominent factor to lower the corrosion rate in acid medium. Atomic force microscopy analysis is also carried out to investigate the effect of HTMBH on the surface of mild steel surface in acid solution. The contact angle measurement showed decreased affinity of mild steel surface for acid solution containing HTMBH. The results obtained from all of these methods showed good consistency.

Ag decorated silica nanostructures for surface plasmon enhanced photocatalysis.

In this article, we present a novel synthesis of mesoporous SiO2/Ag nanostructures for dye (methylene blue) adsorption and surface plasmon mediated photocatalysis. Mesoporous SiO2 nanoparticles with a pore size of 3.2 nm were synthesized using cetyltrimethylammonium bromide as a structure directing agent and functionalized with (3-aminopropyl)trimethoxysilane to introduce amine groups. The adsorption behavior of non-porous SiO2 nanoparticles was compared with that of the mesoporous silica nanoparticles. The large surface area and higher porosity of mesoporous SiO2 facilitated better adsorption of the dye as compared to the non-porous silica. Ag decorated SiO2 nanoparticles were synthesized by attaching silver (Ag) nanoparticles of different morphologies, i.e. spherical and triangular, on amine functionalized silica. The photocatalytic activity of the mesoporous SiO2/Ag was compared with that of non-porous SiO2/Ag nanoparticles and pristine Ag nanoparticles. Mesoporous SiO2 nanoparticles (k d = 31.3 × 10-3 g mg-1 min-1) showed remarkable improvement in the rate of degradation of methylene blue as compared to non-porous SiO2 (k d = 25.1 × 10-3 g mg-1 min-1) and pristine Ag nanoparticles (k d = 19.3 × 10-3 g mg-1 min-1). Blue Ag nanoparticles, owing to their better charge carrier generation and enhanced surface plasmon resonance, exhibited superior photocatalysis performance as compared to yellow Ag nanoparticles in all nanostructures.