pH-responsive polymeric nanoparticles with tunable sizes for targeted drug delivery

Biodegradable nanoparticles (NPs) have shown great promise as intracellular imaging probes, nanocarriers and drug delivery vehicles. In this study, we designed and prepared amphiphilic cellulose derivatives via Schiff base reactions between 2,3-dialdehyde cellulose (DAC) and amino compounds. Polymeric NPs were facilely fabricated via the self-assembly of the as-synthesized amphiphilic macromolecules. The size distribution of the obtained NPs can be tuned by changing the amount and length of the grafted hydrophobic side-chains. Anticancer drugs (DOX) were encapsulated in the NPs and the drug-loaded NPs based on cellulose derivatives were stable in neutral and alkaline environments for at least a month. They rapidly decomposed with the efficient release of the drug in acidic tumor microenvironments. These drug-loaded NPs have the potential for application in cancer treatment.

Novel nanoparticles for efficient drug delivery were designed and constructed using polymeric 2,3-dialdehyde cellulose (DAC). The drug DOX was encapsulated into nanoparticles and underwent thoroughly controlled release in acidic tumor microenvironments.     

Design of a novel poly(aryl ether nitrile)-based composite ultrafiltration membrane with improved permeability and antifouling performance using zwitterionic modified nano-silica

Zwitterionic nano-silica (SiO₂ NPs) obtained by lysine surface modification was used as a hydrophilic inorganic filler for preparing a poly(aryl ether nitrile) (PEN) nanocomposite membrane via an immersion precipitation phase inversion method. The effects of zwitterionic SiO₂ NPs addition on the morphology, separation and antifouling performance of the synthesized membranes were investigated. Zwitterionic surface modification effectively avoided the agglomeration of SiO₂ NPs. The PEN/zwitterionic SiO₂ NPs composite membranes exhibited improved porosity, equilibrium water content, hydrophilicity and permeability due to the introduction of hydrophilic SiO₂ NPs in the casting solution, and the optimal pure water flux was up to 507.2 L m⁻² h⁻¹, while the BSA rejection ratio was maintained at 97.4%. A static adsorption capacity of 72.9 μg cm⁻² and the FRR up to 85.3% in the dynamic antifouling experiment proved that the introduction of zwitterionic SiO₂ NPs inhibited irreversible fouling and enhanced the antifouling ability of the PEN membrane.

Zwitterionic nano-silica (SiO₂ NPs) obtained by lysine surface modification was used as a hydrophilic inorganic filler for preparing a poly(aryl ether nitrile) (PEN) nanocomposite membrane via an immersion precipitation phase inversion method.     

RGD-modified dihydrolipoamide dehydrogenase conjugated to titanium dioxide nanoparticles – switchable integrin-targeted photodynamic treatment of melanoma cells

The photocytotoxic effect of UVA-excited titanium dioxide (TiO₂), which is caused by the generation of reactive oxygen species (ROS), is often used in medical applications, such as cancer treatment. Photodynamic-therapy (PDT) is applied in several cancer models including cutaneous melanoma (CM), however the lack of selectivity causing damage to surrounding healthy tissues limits its applicability and novel targeted-delivery approaches are required. As cancer cells often overexpress integrin receptors (e.g. αvβ₃) on their cell surface, targeted delivery of TiO₂ nanoparticles (NPs) via an Arg-Gly-Asp (RGD) motif would make PDT more selective. We have recently reported that the mitochondrial enzyme dihydrolipoamide dehydrogenase (DLDH) strongly and specifically conjugates TiO₂via coordinative bonds. In this work we have modified DLDH with RGD moieties (DLDH^RGD), creating a molecular bridge between the integrin-expressing cancer cells and the photo-excitable TiO₂ nanoparticles. Physicochemical assays have indicated that the hybrid-conjugated nanobiocomplex, TiO₂–DLDH^RGD, is producing controlled-release ROS under UVA illumination, with anatase NPs being the most photoreactive TiO₂ form. This drug delivery system exhibited a cytotoxic effect in αvβ₃ integrin-expressing mice melanoma cells (B16F10), but not in normal cells lacking this integrin (HEK293). No cytotoxic effect was observed in the absence of UV illumination. Our results demonstrate the feasibility of combining the high efficiency of TiO₂-based PDT, with an integrin-mediated tumor-targeted drug delivery for nanomedicine.

This work presents a UVA switchable integrin-targeted photodynamic therapy in melanoma, composed of an RGD-modified DLDH conjugated to TiO₂ nanoparticles, with high selectivity towards integrin-expressing cancer cells.     

Synthesis of silver sulfide nanoparticles and their photodetector applications

Silver sulfide nanoparticles (Ag₂S NPs) are currently being explored as infrared active nanomaterials that can provide environmentally stable alternatives to heavy metals such as lead. In this paper, we describe the novel synthesis of Ag₂S NPs by using a sonochemistry method and the fabrication of photodetector devices through the integration of Ag₂S NPs atop a graphene sheet. We have also synthesized Li-doped Ag₂S NPs that exhibited a significantly enhanced photodetector sensitivity via their enhanced absorption ability in the UV-NIR region. First-principles calculations based on a density functional theory formalism indicated that Li-doping produced a dramatic enhancement of NIR photoluminescence of the Ag₂S NPs. Finally, high-performance photodetectors based on CVD graphene and Ag₂S NPs were demonstrated and investigated; the hybrid photodetectors based on Ag₂S NPs and Li-doped Ag₂S NPs exhibited a photoresponse of 2723.2 and 4146.0 A W⁻¹ respectively under a light exposure of 0.89 mW cm⁻² at 550 nm. Our novel approach represents a promising and effective method for the synthesis of eco-friendly semiconducting NPs for photoelectric devices.

Silver sulfide nanoparticles (Ag₂S NPs) are currently being explored as infrared active nanomaterials that can provide environmentally stable alternatives to heavy metals such as lead.     

Facile photocatalytic reduction of carcinogenic Cr(vi) on Fe-doped copper sulfide nanostructures

In this study, Fe-doped copper sulfide nanoparticles (NPs) were investigated for the solar-assisted reduction of Cr^VI ions in raw water. The Fe-doped NPs were synthesized by decomposing copper(ii) N,N-diphenylmethylpiperazinecarbamodithioate via a facile single-step, one-pot solvothermal method in the presence of iron salt. The Cr^VI photoreduction data were fit to a pseudo-first-order kinetic model and a Langmuir model. The CuS/Cu₂S NP reduction ability for Cr^VI increases with an increase in dopant percentage. The best catalyst (9% Fe-doped) was able to reduce Cr^VI (10⁻⁴ M K₂Cr₂O₇) to Cr^III in raw water using an initial amount of 10 mg in 6 min with a reduction efficiency of up to 100%. The photocatalytic activity was examined while varying five different parameters: sunlight, diffused light, change in pH, and changes in the concentration of the catalyst and the temperature. This new approach presents an active, simple, and cost-effective means for wastewater treatment.

This article reports Fe-doped copper sulfide nanostructures and their ability to photocatalytically reduce carcinogenic Cr(vi). The best result is shown by 9% Fe-doped CuS, which reduces Cr(vi) in 6 min in the presence of sunlight.     

Hollow carbon-based nanosystem for photoacoustic imaging-guided hydrogenothermal therapy in the second near-infrared window

Compared with the near-infrared-I spectral window (NIR-I, 650–950 nm), a newly developed imaging and treatment window with a 1000–1700 nm range (defined as the NIR-II bio-window) has attracted much attention owing to its higher spatiotemporal resolution, increased tissue penetration depth and therapeutic efficacy. Herein, we designed a nanotheranostic platform (HC-AB NPs) via loading ammonia borane (AB) into hollow carbon nanoparticles (HCs) for NIR-II photoacoustic (PA) imaging-guided NIR-II hydrogenothermal therapy. Importantly, by exploiting the characteristics of beta zeolite as a hard template and a template-carbonization-corrosion process, the prepared HCs have excellent NIR-II absorption performance and AB loading capacity. With the high biocompatibility of HC-AB NPs, an efficient synergistic anti-tumor strategy has been achieved via high intratumoural accumulation and acid-stimulated H₂ release as well as PA-guided precise NIR-II photothermal therapy. The HC-AB NPs as a promising nanotheranostic platform opens a new avenue for high-efficacy NIR-II hydrogenothermal therapy.

We have developed a novel nanotheranostic platform (HC-AB NPs) via loading ammonia borane (AB) into hollow carbon nanoparticles (HCs) for NIR-II photoacoustic (PA) imaging-guided NIR-II hydrogenothermal therapy.     

Novel Au nanorod/Cu2O composite nanoparticles for a high-performance supercapacitor

Metal–oxide nanomaterials have attracted great interest in recent years due to their novel characteristics such as surface effect and quantum confinement. A fascinating Au nanorod (NR)/cuprous oxide core–shell composite (AuNR/Cu₂O) was directly synthesized using a moderate one-pot facile green redox method and further utilized for energy storage applications in a supercapacitor. The synthesis mechanism is based on the use of reducing agents to form the core shell. The resultant composite was deposited on the surface of nickel foam as a result of redox reactions between Au and Cu via a hydrothermal method. AuNR/Cu₂O composite nanoparticles (NPs) were characterized using various spectroscopic and microscopic techniques, including UV-vis and X-ray photoelectron spectroscopies, Brunauer–Emmett–Teller surface area analysis, X-ray diffractometry, and transmission electron microscopy. The AuNR/Cu₂O composite NPs grow via the depositing of a 20–50 nm Cu₂O shell on an AuNR core with dimensions of 5–20 nm in width and 40–70 nm in length. The as-synthesized AuNR/Cu₂O composite NPs were effectively used as electrode materials in a supercapacitor, and their electrochemical performance was determined by cyclic voltammetry, galvanostatic charge–discharge measurements, and electrochemical impedance spectroscopy in 2 M KOH aqueous solution as an electrolyte. The composite NPs showed excellent average specific capacitance of 235 F g⁻¹ at a current density of 2 A g⁻¹ and durable cycling stability (96% even after 10 000 cycles). The higher efficiency of the AuNR/Cu₂O composite NPs can be attributed to the presence of AuNR in the core. The AuNR/Cu₂O composite NPs exhibit a high surface area and high electrical conductivity, which consequently result in their excellent specific capacitance and outstanding rate as an all-solid-state supercapacitor electrode.

Synthesis of an Au/Cu₂O composite and its supercapacitor behavior.     

Fabrication of magnetic iron oxide-supported copper oxide nanoparticles (Fe3O4/CuO): modified screen-printed electrode for electrochemical studies and detection of desipramine

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles (NPs). Fe₃O₄/CuO NPs were synthesized via a coprecipitation procedure, and the products were characterized via energy disperse spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and vibrating sample magnetometer. The voltage–current curve and differential pulse voltammetry examinations of Fe₃O₄/CuO-modified screen-printed electrode (Fe₃O₄/CuO/SPE) were followed by the determination of electro-catalytic activities toward desipramine oxidation in a phosphate buffer solution (pH = 7.0). In addition, the value of diffusion coefficient (D = 3.0 × 10⁻⁶ cm² s⁻¹) for desipramine was calculated. Then, based on the optimum conditions, it was observed that the currents of the oxidation peak were linearly proportionate to the concentration of desipramine in the broad range between 0.08 and 400.0 μM and LOD of 0.03 μM (S/N = 3). Finally, our new sensor was successfully utilized to detect desipramine in the real samples, with reasonable recovery in the range of 97.2% to 102.7%.

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles.     

Vanillin-crosslinked chitosan/ZnO nanocomposites as a drug delivery system for 5-fluorouracil: study on the release behavior via mesoporous ZrO2–Co3O4 nanoparticles modified sensor and antitumor activity

Herein, a series of vanillin-crosslinked chitosan (Vn-CS) nanocomposites (NCs) containing various contents of ZnO nanoparticles (NPs) was prepared and characterized via FTIR spectroscopy, XRD, TGA, SEM and TEM. Changing the weight% of ZnO NPs in the prepared NCs resulted in an improvement in their antibacterial activity against Gram-negative and Gram-positive bacteria strains compared with the unmodified CS, and the encapsulation efficiency of 5-fluorouracil (5-FU) was found to be in the range of 61.4–69.2%. Subsequently, the release of 5-FU was monitored utilizing the mesoporous ZrO₂–Co₃O₄ NPs modified carbon paste sensor via the square-wave adsorptive anodic stripping voltammetry (SW-AdASV) technique. Also, the release mechanism of 5-FU from each NC was studied by applying the zero-order, first-order, Hixson–Crowell and Higuchi models to the experimental results. The cytotoxicity of prepared NCs and 5-FU-encapsulated NCs was evaluated against the HePG-2, MCF-7 and HCT-116 cancer cell lines, in addition to the WI-38 and WISH normal cell lines using the MTT assay. Notably, 5-FU/CV₁₀ NC exhibited the highest antitumor activity towards all tested cancer cell lines and a moderate activity against WI-38 and WISH normal cell lines with IC₅₀ values of 28.02 ± 2.5 and 31.65 ± 2.7 μg mL⁻¹, respectively. The obtained nanocomposites exhibited suitable selectivity with minimum toxicity against normal cells.

Herein, a series of vanillin-crosslinked chitosan (Vn-CS) nanocomposites (NCs) containing various contents of ZnO nanoparticles (NPs) was prepared and characterized via FTIR spectroscopy, XRD, TGA, SEM and TEM.     

Enhanced catalytic activity over palladium supported on ZrO2@C with NaOH-assisted reduction for decomposition of formic acid

A ZrO₂@C support based on t-ZrO₂ embedded in amorphous carbon was obtained via the pyrolysis of a UiO-66 precursor. Highly dispersed Pd nanoparticles (NPs) were subsequently deposited onto this support, using NaOH-assisted reduction, to obtain a formic acid (FA) decomposition catalyst. This material showed a turnover frequency (TOF) for the heterogeneously-catalyzed decomposition of FA of 8588 h⁻¹ at 60 °C, with 100% H₂ selectivity. This performance is ascribed to the uniform dispersion of smaller palladium nanoparticles and a synergistic effect between the metal NPs and support. Even at 30 °C, the complete decomposition of FA was achievable in FA/SF (SF, sodium formate) solution, with a TOF as high as 1857 h⁻¹.

Pd/ZrO₂@C was prepared employing UiO-66-derived ZrO₂@C as the support and showed high catalytic activity for formic acid decomposition.     

A comparison of acyl-moieties for noncovalent functionalization of PLGA and PEG-PLGA nanoparticles with a cell-penetrating peptide

Efficient intracellular drug delivery in nanomedicine strongly depends on ways to induce cellular uptake. Conjugation of nanoparticles (NPs) with cell-penetrating peptides (CPPs) is a known means to induce uptake via endocytosis. Here, we functionalized NPs consisting of either poly(d,l-lactide-co-glycolide) (PLGA) or polyethene glycol (PEG)-PLGA block-copolymer with a lactoferrin-derived cell-penetrating peptide (hLF). To enhance the association between the peptide and the polymer NPs, we tested a range of acyl moieties for N-terminal acylation of the peptide as a means to promote noncovalent interactions. Acyl moieties differed in chain length and number of acyl chains. Peptide-functionalized NPs were characterized for nanoparticle size, overall net charge, storage stability, and intracellular uptake. Coating particles with a palmitoylated hLF resulted in minimal precipitation after storage at −20C and homogeneous particle size (<200 nm). Palmitoyl-hLF coated NPs showed enhanced delivery in different cells in comparison to NPs lacking functionalization. Moreover, in comparison to acetyl-hLF, palmitoyl-hLF was also suited for coating and enhancing the cellular uptake of PEG-PLGA NPs.

Noncovalent functionalization with acylated cell-penetrating peptides achieves an efficient cellular uptake of PLGA and PEG-PLGA nanoparticles.      

Cu2−xSe nanoparticles (Cu2−xSe NPs) mediated neurotoxicity via oxidative stress damage in PC-12 cells and BALB/c mice

Cu_2−xSe nanoparticles (Cu_2−xSe NPs) are widely used for optical diagnostic imaging and photothermal therapy due to their strong near-infrared (NIR) optical absorption. With the continuous expansion of applications using Cu_2−xSe NPs, their biosafety has received increasing attention in recent years. Cu_2−xSe NPs can enter the brain by crossing the blood–brain barrier, but the neurotoxicity of NPs remains unclear. The present investigation provides direct evidence that the toxicity of Cu_2−xSe NPs can be specifically exploited to kill rat pheochromocytoma PC-12 cells (a cell line used as an in vitro model for brain neuron research) in dose- and time-dependent manners. These cytotoxicity events were accompanied by mitochondrial damage, adenosine triphosphate (ATP) depletion, production of oxidizing species (including reactive oxygen species (ROS), malondialdehyde (MDA) and hydrogen peroxide (H₂O₂)), as well as reductions in antioxidant defense systems (glutathione (GSH) and superoxide dismutase (SOD)). Moreover, our in vivo study also confirmed that Cu_2−xSe NPs markedly induced neurotoxicity and oxidative stress damage in the striatum and hippocampal tissues of BALB/c mice. These findings suggest that Cu_2−xSe NPs induce neurotoxicity in PC-12 cells and BALB/c mice via oxidative stress damage, which provides useful information for understanding the neurotoxicity of Cu_2−xSe NPs.

Cu_2−xSe nanoparticles (Cu_2−xSe NPs) are widely used for optical diagnostic imaging and photothermal therapy due to their strong near-infrared (NIR) optical absorption.     

Dual-modal imaging and excellent anticancer efficiency of cisplatin and doxorubicin loaded NaGdF4:Yb3+/Er3+ nanoparticles

NaGdF₄:Yb³⁺/Er³⁺ nanoparticles were synthesized via a modified hydrothermal route. The dependence of structure and morphology on the dosage of sodium polyacrylate was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The as-prepared nanoparticles could be used for T₂ weighted magnetic resonance imaging due to the paramagnetism of Gd³⁺. cis-dichlorodiamineplatinum (CDDP) could be loaded onto NaGdF₄:Yb³⁺/Er³⁺ nanoparticles through binding carboxyl in the form of Pt–O bonds, and doxorubicin (DOX) could be loaded via hydrogen bonding. DOX could also be loaded onto the NaGdF₄–CDDP composite in the same manner, and the loading efficiency of both drugs remained unchanged. Three as-prepared drug delivery systems were used for tumor inhibition both in vitro and in vivo, and the results indicated that NaGdF₄–CDDP–DOX displayed the greatest inhibitory capacity.

The drug delivery system NaGdF₄–CDDP–DOX showed best tumor inhibition capacity both in vitro and in vivo.     

Rapid green-synthesis of TiO2 nanoparticles for therapeutic applications

Nanoparticles (NPs) with sizes ranging from 2 nm to 1 μm find various applications in the field of theranostics. Moreover, if eco-friendly methods are opted for the synthesis of biocompatible and less toxic NPs, then that''s a huge success. Titanium dioxide nanoparticles (TiO₂ NPs) have been vigorously studied for their use in medical implants, photodynamic therapy, drug delivery, biosensing and as antimicrobial agents. The present study reports the green-synthesis of TiO₂ NPs for the first-time using extracts of black pepper (Piper nigrum), coriander (Coriandrum sativum) and clove (Syzygium aromaticum). All three samples of TiO₂ NPs were synthesized via a modified sol–gel method under similar environmental conditions. Similar treatments were given to the samples. The procedure adopted for the synthesis ensures the use of non-toxic materials, no production of toxic by-products and rapid synthesis of the TiO₂ NPs. The NPs were characterized by X-ray diffraction, high resolution-transmission electron microscopy, energy dispersive spectroscopy, field emission scanning electron microscopy and selected area electron diffraction which confirmed the formation, morphology, crystallinity and size of the TiO₂ NPs. These characterizations displayed the similarity index of all three samples. However, photoluminescence and vibrating sample magnetometer studies highlighted the differences among the three samples. All three samples of NPs obtained had a size range of 5–20 nm. Further, the findings showed that different plant extracts result in TiO₂ NPs with moderately different characteristics. Furthermore, the samples were analysed for their drug-encapsulation efficiency using UV-visible spectrophotometry. Among all three samples, the NPs synthesised using black pepper exhibited the maximum encapsulation efficiency. The study concludes that the plant''s bio-profile is responsible for bringing about changes in the traits of the resulting nanoparticles. Thus, the extracts from different plants have the ability to manipulate the properties of the synthesized NPs. These findings can help to understand the role and importance of the plants in synthesizing NPs for biomedical applications. A further detailed study in this field can help researchers to understand the influence of the plant''s biochemistry in shaping the NPs.

Synthesis of TiO₂ nanoparticles using three different plant extracts results in different properties of the individual samples.     

Interzeolite conversion of a micronsized FAU to a nanosized CHA zeolite free of organic structure directing agent with a high CO2 capacity

The interzeolite transformation of a micronsized FAU zeolite to a nanosized CHA zeolite via alkali treatment is presented. The impact of the selection of the FAU zeolite starting material on the properties of the produced CHA zeolite was analyzed by XRD, ICP, SEM, TEM, N₂ and CO₂ adsorption, and in situ FT-IR. The analysis showed that the choice of starting FAU zeolite had a large impact on the chemical composition, size, morphology, and porosity of the produced CHA zeolite. The as prepared CHA samples show high capacity toward CO₂ (4.26 mmol g⁻¹) and it was demonstrated that the chemisorbed vs. physisorbed CO₂ was controlled by varying the amount of alkali cations in the CHA zeolite.

The interzeolite transformation of a micronsized FAU zeolite to a nanosized CHA zeolite via alkali treatment is presented.     

Engineering of NIR fluorescent PEGylated poly(RGD) proteinoid polymers and nanoparticles for drug delivery applications in chicken embryo and mouse models

Proteinoids are non-toxic biodegradable polymers based on thermal step-growth polymerization of natural or synthetic amino acids. Hollow proteinoid nanoparticles (NPs) may then be formed via a self-assembly process of the proteinoid polymers in an aqueous solution. In the present article polymers and NPs based on d-arginine, glycine and l-aspartic acid, poly(R^DGD), were synthesized for tumor targeting, particularly due to the high affinity of the RGD motif to areas of angiogenesis. Near IR fluorescent P(R^DGD) NPs were prepared by encapsulating the fluorescent NIR dye indocyanine green (ICG) within the formed P(R^DGD) NPs. Here, we investigate the effect of the covalent conjugation of polyethylene glycol (PEG), with different molecular weights, to the surface of the near IR encapsulated P(R^DGD) NPs on the release of the dye to human serum due to bio-degradation of the proteinoid NPs and on the uptake by tumors. This work illustrates that the release of the encapsulated ICG from the non-PEGylated NPs is significantly faster than for that observed for the PEGylated NPs, and that the higher molecular weight is the bound PEG spacer the slower is the dye release profile. In addition, in a chicken embryo model, the non-PEGylated ICG-encapsulated P(R^DGD) NPs exhibited a higher uptake in the tumor region in comparison to the PEGylated ICG-encapsulated P(R^DGD) NPs. However, in a tumor xenograft mouse model, which enables a prolonged experiment, the importance of the PEG is clearly noticeable, when a high concentration of PEGylated P(R^DGD) NPs was accumulated in the area of the tumor compared to the non-PEGylated P(R^DGD). Moreover, the length of the PEG chain plays a major role in the ability to target the tumor. Hence, we can conclude that selectivity towards the tumor area of non-PEGylated and the PEGylated ICG-encapsulated P(R^DGD) NPs can be utilized for targeting to areas of angiogenesis, such as in the cases of tumors, wounds or cuts, etc.

Synthesis of NIR/ICG PEGylated poly(R^DGD) proteinoid NPs and their drug delivery towards mCherry-labeled 4T1 tumor.     

Photoluminescence,TGA/DSC and photocatalytic activity studies of Dy3+ doped SrY2O4 nanophosphors

Dy³⁺:SrY₂O₄ nanophosphors were prepared via a solution combustion method using glycine as an organic fuel. The structural, optical, and thermal properties of the nanophosphors were studied. Strain and crystal size were calculated via W–H analysis. The direct energy band gap is nearly 4.9 eV and photocatalytic studies reveal that Rh-B degradation of almost 50% can be achieved.

Photoluminescence properties of Dy³⁺:SrY₂O₄ nanophosphors designed for warm w-LED applications.     

Metal-enhanced fluorescence in polymer composite films with Au@Ag@SiO2 nanoparticles and InP@ZnS quantum dots

For white light-emitting diode (LED) applications, semiconductor quantum dots (QDs) have been widely utilized as efficient down-converters to change the blue color of the light source into different emission colors. Because QDs offer spectral tunability over the entire visible light range, as well as improved color purity, they have rapidly replaced conventional phosphor-based white LEDs. However, for the sustainable growth of QD-mediated LEDs, the amount of QDs required must be reduced by enhancing the color-conversion efficiency. For this purpose, we prepared poly(lauryl methacrylate) (PLMA) composite films by the photo-crosslinking polymerization of lauryl methacrylate monomers in the presence of Au@Ag@SiO₂ nanoparticles (NPs) and InP@ZnS QDs. In the PLMA composites, the Au@Ag NPs not only amplified the blue light source but also modified the relaxation of the excited QDs via localized surface plasmon resonance. This resulted in a maximum 12.9-fold enhancement in the QD fluorescence. Because the blue light source in this study can be easily replaced by blue LEDs, the enhanced efficiency of QD emissions via the plasmonic effect could potentially increase the performance of QDs for display applications.

Poly(lauryl methacrylate) films containing Au@Ag@SiO₂ nanoparticles and InP@ZnS quantum dots were prepared to investigate metal-enhanced fluorescence in polymer composites.     

Colorimetric sensing of chlorpyrifos through negative feedback inhibition of the catalytic activity of silver phosphate oxygenase nanozymes

Intensive use of organophosphate chlorpyrifos pesticides in farming has become a serious issue due to their harmful effects on living beings. Most fruits, vegetables and soil contain chlorpyrifos, and it cannot be rinsed out completely by water washing. Therefore, a selective and sensitive detection of chlorpyrifos is significant. In the present study, the intriguing oxidase-mimicking activity of Ag₃PO₄ nanoparticles (NPs) is explored for the fast and selective detection of chlorpyrifos pesticides. Ag₃PO₄ NPs exhibit several advantages, such as great catalytic efficiency, high stability, monodispersity and reusability, over other expensive nanozymes via a facile one-step sensing. The size, shape, crystal planes and diffraction patterns of the Ag₃PO₄ NPs were observed via FESEM and HR-TEM. The surface properties and oxidation states were analyzed via XPS technique. Ag₃PO₄ NPs possess intrinsic excellent oxidase-mimicking properties against 3,3′,5,5′-tetramethylbezidyne (TMB). When chlorpyrifos and Ag₃PO₄ NP nanozymes come in proper orientation proximity, chlorpyrifos is oxidized. The oxidized chlorpyrifos produces sulfide ions and chlorpyrifos oxon. The produced sulfide ions in the reaction system interact with Ag₃PO₄ NPs and inhibit their catalytic activity by feedback inhibition. Indeed, neither any catalytic site is left to oxidize TMB nor any blue colour appears. Thus, this feedback inhibition phenomenon senses chlorpyrifos pesticides. The calculated limit of detection (LOD) for the standard chlorpyrifos is ∼9.97 ppm, and the efficacy of the Ag₃PO₄ NPs calculated in terms of the K_m value was found to be 0.15 mM. A real sample analysis was carried out by the standard addition method with two soil samples collected from Pethapur and Chiloda villages.

Ag₃PO₄ oxygenase nanozymatic activity towards chlorpyrifos sensing.     

Synthesis and characterization of nickel-doped ceria nanoparticles with improved surface reducibility

Nickel-doped ceria nanoparticles (Ni_0.1Ce_0.9O_2−x NPs) were fabricated from Schiff-base complexes and characterized by various microscopic and spectroscopic methods. Clear evidence is provided for incorporation of nickel ions in the ceria lattice in the form of Ni³⁺ species which is considered as the hole trapped state of Ni²⁺. The Ni_0.1Ce_0.9O_2−x NPs exhibit enhanced reducibility in H₂ as compared to conventional ceria-supported Ni particles, while in O₂ the dopant nickel cations are oxidized at higher valence than the supported ones.

Nickel-doped ceria nanoparticles (Ni_0.1Ce_0.9O_2−x NPs) were fabricated from Schiff-base complexes and characterized by various microscopic and spectroscopic methods.