Sustainable, Rapid Synthesis of Bright-Luminescent CuInS2-ZnS Alloyed Nanocrystals: Multistage Nano-xenotoxicity Assessment and Intravital Fluorescence Bioimaging in Zebrafish-Embryos

Highly efficient and stable tandem luminescent solar concentrators based on carbon dots and CuInSe2-xSx/ZnS quantum dots

Semi-transparent large-area luminescent solar concentrators (LSCs) have been considered an essential part of zero-energy or low-energy consuming buildings in the future. Inorganic colloidal quantum dots (QDs) are promising candidates for LSCs due to the advantages of a tunable bandgap, engineered large Stokes shift, and relatively high photoluminescence (PL) quantum yield. However, LSCs that are fabricated using colloidal quantum dots exhibited an inferior stability under long-term illumination, demanding great efforts to explore the highly stable LSCs. Herein, we fabricated large-area (∼100 cm2) tandem LSCs based on highly stable carbon dots (CDs) and highly luminescent near-infrared emitting CuInSe2-xSx/ZnS (CuInSeS/ZnS) QDs. Coupled with a Si diode as a reference, the power conversion efficiency of the corresponding tandem (dimensions: 10 × 10 × 0.5 cm3) and single LSCs (dimensions: 10 × 10 × 0.3 cm3) based on CuInSeS/ZnS QDs under one sun illumination are 0.46% and 0.5%, respectively. For single CuInSeS/ZnS QD based LSCs at a low concentration (0.039 wt%), external and internal quantum efficiencies reach up to 2.87% and 36.37%, respectively. After UV illumination for 8 h, bottom LSCs based on CuInSeS/ZnS QDs retain 93.22% of the initial PL emission, which is higher than that of LSCs (∼80%) without the CD protection. The highly efficient and stable tandem LSCs employing green CDs and NIR CuInSeS/ZnS QDs as PL emitters pave the way for the realization of large area building-integrated photovoltaic (BIPV) devices.

Copper indium sulfide quantum dots in photocatalysis

Since the advent of photocatalytic technology, scientists have been searching for semiconductor materials with high efficiency in solar energy utilization and conversion to chemical energy. Recently, the development of quantum dot (QD) photocatalysts has attracted much attention because of their unique characteristics: small size, quantum effects, strong surface activity, and wide photoresponse range. Among ternary chalcogenide semiconductors, CuInS₂ QDs are increasingly examined in the field of photocatalysis due to their high absorption coefficients, good matching of the absorption range with sunlight spectrum, long lifetimes of photogenerated electron-hole pairs and environmental sustainability. In this review paper, the structural and electronic properties, synthesis methods and various photocatalytic applications of CuInS₂ QDs are systematically expounded. The current research status on the photocatalytic properties of materials based on CuInS₂ QD is discussed combined with the existing modification approaches for the enhancement of their performances. Future challenges and new development opportunities of CuInS₂ QDs in the field of photocatalysis are then prospected.

Luminescent AgGaSe2/ZnSe nanocrystals: rapid synthesis, color tunability, aqueous phase transfer, and bio-labeling application

The unique optoelectronic properties of I-III-VI₂ nanocrystals (NCs) have attracted extensive attention. Herein, element Se in oleylamine reduced by alkythiol, which has been demonstrated to generate highly reactive alkylammonium selenide, was selected as the Se precursor by us to successfully synthesize high-quality tetragonal AgGaSe₂ NCs via a facile colloidal method in just 2 minutes. Further, the photoluminescence (PL) properties of the as-synthesized AgGaSe₂ NCs were systematically optimized through utilizing one Zn precursor to integrate shell coating and anionic/cationic alloying strategies into our reactive system, resulting in not only the obvious improvement of PL intensity but also tunable PL color from blue to red. Furthermore, the ligand exchange approach was adopted for the aqueous phase transfer of the oleophilic AgGaSe₂/ZnSe NCs. Our data suggest that either metalated mercaptopropionic acid (Zn-MPA) short- or 11-mercaptoundecanoic acid long-chain ligand exchanged NCs all could maintain the original high crystallinity, present good water solubility, and retain up to nearly 95% and 70% of the initial PL intensity, respectively. Benefiting from the low cytotoxicity, the water-soluble AgGaSe₂/ZnSe NCs can be applied as a fluorescent probe in cell imaging and signal labels for the fluoroimmunoassay of prostate-specific antigen, implying their potential in biological application.

Biocompatible CuInS2 Nanoparticles as Potential Antimicrobial, Antioxidant, and Cytotoxic Agents

A simple hydrothermal route is employed to synthesize pure copper indium disulfide (CIS) and CIS nanoparticles (NPs) mediated by various natural plant extracts. The plant extracts used to mediate are Azadirachta indica (neem), Ocimum sanctum (basil), Cocos nucifera (coconut), Aloe vera (aloe), and Curcuma longa (turmeric). The tetragonal unit cell structure of as-synthesized NPs is confirmed by X-ray diffraction. The analysis by energy-dispersive X-rays shows that all the samples are near-stoichiometric. The morphologies of the NPs are confirmed by high-resolution scanning and transmission modes of electron microscopy. The thermal stability of the synthesized NPs is determined by thermogravimetric analysis. The optical energy band gap is determined from the absorption spectra using Tauc's equation. The antimicrobial activity analysis and the estimation of the minimum inhibitory concentration (MIC) value of the samples are performed for Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter aerogenes, and Staphylococcus aureus pathogens. It shows that the aloe-mediated CIS NPs possess a broad inhibitory spectrum. The best inhibitory effect is observed against S. aureus, whereas the least effect was exhibited against P. vulgaris. The least MIC value is found for aloe-mediated CIS NPs (0.300 mg/mL) against S. aureus, P. aeruginosa, and E. aerogenes, along with basil-mediated NPs against E. coli. The antioxidant activity study showed that the IC50 value to inhibit the scavenging activity is maximum for the control (vitamin C) and minimum for pure CIS NPs. The in vivo cytotoxicity study using brine shrimp eggs shows that the pure CIS NPs are more lethal to brine shrimp than the natural extract-mediated CIS NPs. The in vitro cytotoxicity study using the human lung carcinoma cell line (A549) shows that the IC50 value of turmeric extract-mediated CIS NPs is minimum (15.62 ± 1.58 μg/mL). This observation reveals that turmeric extract-mediated CIS NPs are the most potent in terms of cytotoxicity toward the A549 cell line.

Green synthesis of silver indium telluride nanocrystals: characterization and photothermal analyses

Here, we report the preparation and characterization of stable AgIn₅Te₈ (AITe) nanocrystals (NCs) and their respective AITe-ZnS and AITe-ZnSe alloys. A green route of synthesis is described by using an aqueous electrochemical method in a cavity cell. The elemental ratio modulation of the NCs was investigated to determine the ideal improvement of the structural and electronic properties. The AITe NCs presented an emission band at 889 nm and hypsochromic shifts when coated with ZnS and ZnSe seeds. Photothermal analyses point to theranostic applications.

Layered PtSe2 for Sensing, Photonic, and (Opto-)Electronic Applications

Since the first experimental discovery of graphene 16 years ago, many other 2D layered nanomaterials have been reported. However, the majority of 2D nanostructures suffer from relatively complicated fabrication processes that have bottlenecked their development and their uptake by industry for practical applications. Here, the recent progress in sensing, photonic, and (opto-)electronic applications of PtSe₂ , a 2D layered material that is likely to be used in industries benefiting from its high air-stability and semiconductor-technology-compatible fabrication methods, is reviewed. The advantages and disadvantages of a range of synthesis methods for PtSe₂ are initially compared, followed by a discussion of its outstanding properties, and industrial and commercial advantages. Research focused on the broadband nonlinear photonic properties of PtSe₂ , as well as reports of its use as a saturable absorber in ultrafast lasers, are then reviewed. Additionally, the advances that have been achieved in a range of PtSe₂ -based field-effect transistors, photodetectors, and sensors are summarized. Finally, a conclusion on these results along with the outlook for the future is presented.

Carbon quantum dots derived from the extracellular polymeric substance of anaerobic ammonium oxidation granular sludge for detection of trace Mn(vii) and Cr(vi)

Carbon quantum dots (CQDs) were synthesized via a hydrothermal method, in which extracellular polymeric substance (EPS) from anaerobic ammonium oxidation (anammox) granular sludge was used as a carbon precursor, while citric acid and ethylenediamine were applied as auxiliary carbon source and passivation agent, respectively. The synthesized CQDs, with orderly spherical shape and mean size of 7.15 nm, emitted blue fluorescent light under UV radiation of 365 nm. The CQDs had a high fluorescence yield (40.84%), with good water solubility and excellent spectroscopic properties. In addition, the CQDs exhibited selective, sensitive and distinctive fluorescence quenching behaviors for Cr(vi) and Mn(vii) in a PBS buffer solution (NaH₂PO₄–Na₂HPO₄) of pH 7, with a detection limit of 5.8 nM for Cr(vi) and 2.3 nM for Mn(vii). Owing to the nitrogen components from the EPS of anammox granules, the CQDs were well nitrogen-doped, promoting electron-transfer and leading to reduction between the CQDs and Mn(vii)/Cr(vi). These results indicate that CQD-based chemical sensing is a simple and efficient means for the fluorescence detection of Mn(vii) and Cr(vi).

Fluorescence detection of trace Mn(vii) or Cr(vi) by the CQDs prepared from anaerobic ammonium oxidation granular sludge.

Waterborne and dietary accumulation of well-dispersible hematite nanoparticles by zebrafish at different life stages

The widespread use of nanoparticles (NPs) has drawn considerable attention because of their potential toxicity and the environmental consequences thereof. However, the effects of the exposure route and life stage of an organism on the bioaccumulation and toxicity of NPs are largely unknown. In the present study, we investigated the accumulation kinetics (uptake, assimilation, and efflux) and tissue distribution of waterborne and dietary hematite NPs (HemNPs) during three life stages (embryo, larva, and adult) of the zebrafish Danio rerio. For all zebrafish life stages, the waterborne accumulation of well-dispersed HemNPs increased linearly with exposure time but decreased after reaching a maximum. The increase in HemNPs accumulation followed the order embryo > larva > adult. Compared with the waterborne route, the dietary accumulation of HemNPs in larval and adult zebrafish fluctuated, reaching a maximum after each food refreshment and then decreasing until the next food addition. Similar to waterborne exposure, adult fish accumulated less dietary HemNPs than did larvae. Nevertheless, dietary HemNPs mostly accumulated in the intestinal tract, with smaller amounts in the truncus, head, and gills, as compared with their waterborne counterparts. Moreover, in the gonad no dietary HemNPs were detected whereas accumulation via waterborne HemNPs was significant. Despite the low assimilation efficiency of dietary HemNPs, biodynamic modeling showed that the diet was the main source of particle accumulation in zebrafish. Thus, both the life stage and the exposure route should be considered in evaluations of the environmental risks of NPs.

Human Umbilical Cord Wharton's Jelly-Derived Mesenchymal Stem Cells Labeled with Mn2+ and Gd3+ Co-Doped CuInS2-ZnS Nanocrystals for Multimodality Imaging in a Tumor Mice Model

Mesenchymal stem cell (MSCs) therapy has recently received profound interest as a targeting platform in cancer theranostics because of inherent tumor-homing abilities. However, the terminal tracking of MSCs engraftment by fluorescent in situ hybridization, immuno-histochemistry, and flow-cytometry techniques to translate into clinics is still challenging because of a dearth of inherent MSCs-specific markers and FDA approval for genetic modifications of MSCs. To address this challenge, a cost-effective noninvasive imaging technology based on multifunctional nanocrystals (NCs) with enhanced detection sensitivity, spatial-temporal resolution, and deep-tissue diagnosis is needed to be developed to track the transplanted stem cells. A hassle-free labeling of human umbilical cord Wharton's Jelly (WJ)-derived MSCs with Mn²⁺ and Gd³⁺ co-doped CuInS₂-ZnS (CIS-ZMGS) NCs has been demonstrated in 2 h without requiring an electroporation process or transfection agents. It has been found that WJ-MSCs labeling did not affect their multilineage differentiation (adipocyte, osteocyte, chondrocyte), immuno-phenotypes (CD44⁺, CD105⁺, CD90⁺), protein (β-actin, vimentin, CD73, α-SMCA), and gene expressions. Interestingly, CIS-ZMGS-NCs-labeled WJ-MSCs exhibit near-infrared (NIR) fluorescence with a quantum yield of 84%, radiant intensity of ∼3.999 × 10¹¹ (p/s/cm²/sr)/(μW/cm²), magnetic relaxivity (longitudinal r₁ = 2.26 mM^-1 s^-1, transverse r₂ = 16.47 mM^-1 s^-1), and X-ray attenuation (78 HU) potential for early noninvasive multimodality imaging of a subcutaneous melanoma in B16F10-tumor-bearing C57BL/6 mice in 6 h. The ex vivo imaging and inductively coupled plasma mass-spectroscopy analyses of excised organs along with confocal microscopy and immunofluorescence of tumor results also significantly confirmed the positive tropism of CIS-ZMGS-NCs-labeled WJ-MSCs in the tumor environment. Hence, we propose the magnetofluorescent CIS-ZMGS-NCs-labeled WJ-MSCs as a next-generation nanobioprobe of three commonly used imaging modalities for stem cell-assisted anticancer therapy and tracking tissue/organ regenerations.

Noninvasive Tracking and Regenerative Capabilities of Transplanted Human Umbilical Cord-Derived Mesenchymal Stem Cells Labeled with I-III-IV Semiconducting Nanocrystals in Liver-Injured Living Mice

Acute liver injury is a critical syndrome ascribed to prevalent death of hepatocytes and imperatively requires liver transplantation. Such a methodology is certainly hampered due to the deficit of healthy donors. In this regard, stem cell-based regenerative therapies are attractive in repairing injured tissues and organs for medical applications. However, it is crucial to understand the migration, engraftment, and regeneration capabilities of transplanted stem cells in the living animal models. For the first time, we demonstrate rapid labeling of umbilical cord-derived mesenchymal stem cells (MSCs) with near-infrared (NIR)-fluorescent CuInS₂-ZnS nanocrystals (CIZS-NCs) to develop innovative nanobioconjugates (MSCs-CIZS-NBCs) that exhibit 98% labeling efficiency. Before nanobioconjugate synthesis, the pristine CIZS-NCs were prepared via a two-step, hot-injection, rapid and low-cost domestic-microwave-refluxing (MW-R) method within 6 min. The as-synthesized CIZS-NCs display high photoluminescence quantum yield (∼88%) and long-lived lifetime (23.4 μs). In contrast to unlabeled MSCs, the MSCs-CIZS nanobioconjugates show excellent biocompatibility without affecting the stemness, as confirmed by cell viability, immunophenotyping (CD44⁺, CD105⁺, CD90⁺), multi-lineage-specific gene expressions, and differentiation into adipocytes, osteocytes, and chondrocytes. The in vivo fluorescence tracking analyses revealed that the MSCs-CIZS-NBCs after tail-vein injection were initially trapped in the lungs and gradually engrafted in the injured liver within 2 h. The regeneration potential of MSCs-CIZS-NBCs was confirmed via renewal of the portal tract composed of portal veins, bile ducts, and hepatic arteries around the hepatocytes. Consequently, no apparent inflammations, necrosis, or apoptosis was observed in the acetaminophen (APAP)-induced liver-injured BALB/c mice model over 3 days after transplantation, as corroborated using laser-scanning confocal microscopy and histopathological and hematological analyses. Hence, our innovative NIR-fluorescent MSCs-CIZS-NBCs offer an off-the-self technology for noninvasive tracking of transplanted MSCs in an acute-liver-injured animal model for future image-guided cell-therapies.

Transition Metal Ion (Mn2+, Fe2+, Co2+, and Ni2+)-Doped Carbon Dots Synthesized via Microwave-Assisted Pyrolysis: A Potential Nanoprobe for Magneto-fluorescent Dual-Modality Bioimaging

Heteroatom-doped carbon dots (C-dots) have captured widespread research interest owing to high fluorescence and biocompatibility for multimodal bioimaging applications. Here, we exemplify a rapid, facile synthesis of ethylenediamine (EDA)-functionalized transition metal ion (Mn²⁺, Fe²⁺, Co²⁺, and Ni²⁺)-doped C-dots via one-pot microwave (MW)-assisted pyrolysis at 800 W within 6 min using Citrus limon (lemon) extract as a carbon source. During MW pyrolysis, the precursor extract undergoes simultaneous carbonization and doping of metal ions onto C-dot surfaces in the presence of EDA. The EDA-functionalized transition metal ion-doped C-dots (i.e., Mn/C, Fe/C, Co/C, and Ni/C-dots) are collectively termed as TMCDs. The water-soluble TMCDs exhibited a size of 3.2 ± 0.485 nm and were enriched with amino and oxo functionalities and corresponding metal-oxide traces on the surfaces, as revealed from Fourier transfer infrared and X-ray photoelectron spectroscopy analyses. Interestingly, TMCDs demonstrated excitation-wavelength-dependent emission with brighter photoluminescence (PL) at 460 nm. Compared to pristine C-dots with a PL quantum yield (QY) of 48.31% and a fluorescence lifetime of 3.6 ns, the synthesized Mn/C, Fe/C, Co/C, and Ni/C-dots exhibited PL QY values of 35.71, 41.72, 75.07, and 50.84% as well as enhanced fluorescence lifetimes (τ_av) of 9.4, 8.6, 9.2, and 8.9 ns, respectively. The TMCDs significantly exhibited enhanced biocompatibility in human colon cancer cells (SW480) for fluorescence bioimaging and showed ferromagnetic and superparamagnetic behavior with vibrant T₁-contrast ability. Interestingly, the maximum longitudinal (r₁) relaxivity of 0.341 mM^-1 s^-1 was observed for Mn/C-dots in comparison to that of 3.1-3.5 mM^-1 s^-1 of clinically used Gd-DTPA magnetic resonance (MR)-contrast agent in vitro (1.5 T). Similarly, the maximum longitudinal relaxivity (r₁) of 0.356 mM^-1 s^-1 was observed for Ni/C-dots (1.5 T) with respect to 4.16 ± 0.02 mM^-1 s^-1 attained for Gd-DTPA in vivo (8.45 T). Thus, the rapid, energy-efficient MW-assisted pyrolysis presents lemon extract derived, EDA-functionalized TMCDs with enhanced PL and efficient T₁ contrast as potential magneto-fluorescent nanoprobes for dual-modality bioimaging applications.

Zebrafish: A Premier Vertebrate Model for Biomedical Research in Indian Scenario

The zebrafish (Danio rerio) is a versatile model organism that has been used in biomedical research for several decades to study a wide range of biological phenomena. There are many technical advantages of using zebrafish over other vertebrate models. They are readily available, hardy, easy, and inexpensive to maintain in the laboratory, have a short life cycle, and have excellent fecundity. Due to its optical clarity and reproducible capabilities, it has become one of the predominant models of human genetic diseases. Zebrafish research has made rapid strides in the United States and Europe, but in India the field is at an early stage and many researchers still remain unaware of the full research potential of this tiny fish. The zebrafish model system was introduced into India in the early 2000s. Up to now, more than 200 scientific referred articles have been published by Indian researchers. This review gives an overview of the current state of knowledge for zebrafish research in India, with the aim of promoting wider utilization of zebrafish for high level biological studies.

Compound Copper Chalcogenide Nanocrystals

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), energy storage (lithium-ion batteries, hydrogen generation), emissive materials (plasmonics, LEDs, biolabelling), sensors (electrochemical, biochemical), biomedical devices (magnetic resonance imaging, X-ray computer tomography), and medical therapies (photochemothermal therapies, immunotherapy, radiotherapy, and drug delivery). The confluence of advances in the synthesis, assembly, and application of these NCs in the past decade has the potential to significantly impact society, both economically and environmentally.

Microwave-solvothermal synthesis of various TiO2 nano-morphologies with enhanced efficiency by incorporating Ni nanoparticles in an electrolyte for dye-sensitized solar cells

A novel systematic approach is demonstrated to enhance the efficiency of dye-sensitized solar cells by impregnating Ni-nanoparticles into I⁻/I₃⁻ electrolyte with various TiO₂ nanomorphologies-based photo-anodes synthesized via microwave-solvothermal process.

Synthetic strategies and biomedical applications of I–III–VI ternary quantum dots

In this review, we discuss recent advances of I–III–VI QDs with a major focus on synthesis and biomedical applications; advantages include low toxicity and fluorescent tuning in the biological window.

One-pot microwave-assisted in situ reduction of Ag+and Au3+ions by Citrus limon extract and their carbon-dots based nanohybrids: a potential nano-bioprobe for cancer cellular imaging

In situreduction and microwave-assisted synthesis of Ag/C-dot and Au/C-dot nanohybrids using natural lemon extract for cancer cellular imaging applications.