Nanoscale Research Letters最新文献

In the vicinity of plasmonic nanostructures that support highly confined light fields, spontaneous emission processes, such as two-photon spontaneous emission (TPSE), exhibit higher-order multipolar emission pathways beyond the dipolar one. These multipolar emission channels occur simultaneously and can interfere with each other. We develop a novel framework that computes these interference effects for TPSE of a quantum emitter close to an arbitrary nanostructure. The model is based on the computation of Purcell factors that can be calculated with conventional electromagnetic simulations, which avoids complex analytic calculations for the environment. For a transition of a hydrogen-like emitter close to a graphene nanotriangle, we demonstrate a breakdown of the dipolar selection rule in the TPSE process. This breakdown is due to a huge enhancement of the two-electric dipole (2ED) and of the two-electric quadrupole (2EQ) transitions. We observe an important interference between these multipolar transitions, as it increases the total rate by (67 , %). In the end, our framework is a complete tool to design emitters and nanostructures for TPSE, where the exploitation of previously ignored interference effects provides an additional degree of freedom, for example to boost desired transitions and to supress undesirable ones.

Novel sensing applications benefit from multifunctional nanomaterials responsive to various external stimuli such as mechanics, electricity, light, humidity, or pollution. While few such materials occur naturally, the careful design of synergized nanomaterials unifies the cross-coupled properties which are weak or absent in single-phase materials. In this study, 2D MoS₂ integrated with ultrathin dielectric oxide layers forms hetero-nanostructures with significant impacts on carrier transport. The ternary TiO₂/MoS₂/ZnO hetero-nanostructures, along with their individual properties, improve the performance of multifunctional sensing devices. The synthesized hetero-nanostructure exhibits a responsivity of up to 16 mA/W to 700 nm light and responds to 5 ppm ammonia gas at room temperature. These enhancements are attributed to interface charge transfer and photogating effects. The ternary TiO₂/MoS₂/ZnO hetero-nanostructure is compatible with existing semiconductor fabrication technologies, making it feasible to integrate into flexible, lightweight semiconductor devices and circuits. These results may inspire new photodetectors and sensing devices based on two-dimensional (2D) layered materials for IoT applications.

Acinetobacter baumannii, an opportunistic pathogen has shown an upsurge in its multi-drug resistant isolates. OmpA of A. baumannii induces incomplete autophagy and apoptosis in host cells. Various therapeutic alternatives are under investigation against A. baumannii. Here, the major emphasis has been laid on comparing the efficacy of AgNP with different capping agents. OmpA targeted lead, Ivermectin capped AgNP (IVM-AgNP) has been compared with the antibacterial polyvinylpyrrolidone capped AgNP (PVP-AgNP) for their role in the modulations of host autophagy. Upregulation of p62 and LC3B confirmed by real-time PCR analysis indicated an increased autophagic flux upon the treatment with AgNPs. The elongation and closure of autophagic vacuoles was also supported by upregulated Atg genes (Atg4, Atg3, Atg5) in A. baumannii infected cells after treatment with AgNP. Autophagic flux increased on treatment with PVP-AgNP as suggested by the rise in mcherryLC3B fluorescence in A549 cells treated with PVP-AgNP as compared to the GFP-LC3B of IVM-AgNP. This suggests that PVP-AgNP treatment more effectively promotes the elongation and maturation stages of autophagy by increasing autophagic flux. These results indicate that capped AgNPs have the efficiency to revert the incomplete autophagy induced by A. baumannii back to normal autophagic levels.

Radiotherapy is prevalently applied for highly effective cancer therapy while the low specificity of radiation is deleterious to the nearby healthy cells. High-Z-based nanomaterials offer excellent radio-enhancement properties while natural products provide radioprotection. Modulation of the radiotherapeutic index via applying nanomaterials is feasible for effective treatment however, the scenario changes when simultaneous protection of non-cancerous cells is required. Here, we report the modulatory radiotherapeutic effect of curcumin conjugated gold nanoparticles in a single nanoformulation to pave the long-awaited hope of a single combination-based, cell-selective radio enhancer, and protectant for cancer radiotherapy. We have validated the effective radiation dose along with the combination of the radio-nano-modulator by a reverse experimentation statistical model. The concept was supported by different sets of experiments, like quantification of ROS generation, cell cycle monitoring, mitochondrial membrane potential measurement, etc. along with gene expression study, and predictive modeling of molecular pathways of the killing mechanism. In conclusion, the nanoconjugate showed a promise to become a candidate for the pH-dependent cell-specific radio-modulator.

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Graphene oxide (GO) and M13 bacteriophage can self-assemble to form ultra-low density porous structures, known as GraPhage13 aerogels (GPA). Due to the insulating nature of GPA and the challenges in producing highly conductive aerogels, it is paramount to explore ways to enhance the conductivity of GPA. Herein, we have developed a method to enhance the conductivity of GPA, via the integration and optimisation of 5 nm and 20 nm diameter gold nanoparticles (AuNPs) into the aerogel structure and systematically analysed the morphology, composition and spectroscopic properties of the resulting GPA-Au nanocomposite. The fabricated GPA-Au nanocomposites exhibited remarkable increases in conductivity, with the integration of 5 nm AuNPs leading to a 53-fold increase compared to GPA, achieving a performance of up to 360 nS/cm, which is within the range suitable for miniaturised semiconductor devices. The mechanism behind the conductivity enhancement was further investigated and attributed to GO-AuNP interactions increasing the carrier density by introducing new energy levels in the GO band gap or shifting its Fermi level towards the conduction band. These findings demonstrate the potential of functionalised AuNPs to significantly improve the electrical properties of GPA, paving the way for their application in gas sensors for biological and chemical detection and a new range of advanced semiconductor devices.

With the size of the aging population increasing worldwide, the effective diagnosis and treatment of neurodegenerative diseases (NDDs) has become more important. Two-dimensional (2D) materials offer specific advantages for the diagnosis and treatment of NDDs due to their high sensitivity, selectivity, stability, and biocompatibility, as well as their excellent physical and chemical characteristics. As such, 2D materials offer a promising avenue for the development of highly sensitive, selective, and biocompatible theragnostics. This review provides an interdisciplinary overview of advanced 2D materials and their use in biosensors, drug delivery, and tissue engineering/regenerative medicine for the diagnosis and/or treatment of NDDs. The development of 2D material-based biosensors has enabled the early detection and monitoring of NDDs via the precise detection of biomarkers or biological changes, while 2D material-based drug delivery systems offer the targeted and controlled release of therapeutics to the brain, crossing the blood–brain barrier and enhancing treatment effectiveness. In addition, when used in tissue engineering and regenerative medicine, 2D materials facilitate cell growth, differentiation, and tissue regeneration to restore neuronal functions and repair damaged neural networks. Overall, 2D materials show great promise for use in the advanced treatment of NDDs, thus improving the quality of life for patients in an aging population.

This study explores the potential of zinc and silver nanocomposites, synthesized with β-lactoglobulin, a whey protein, in promoting wound healing, using the C57BL/6J mouse model. Our research is distinct in its dual focus: assessing the antimicrobial efficacy of these nanocomposites and their impact on wound healing processes. The antimicrobial properties were investigated through minimum inhibitory concentration (MIC) assessments and colony-forming unit (CFU) tests, providing insights into their effectiveness against wound-associated microorganisms. Notably, the formulation's effective antibacterial concentration did not exhibit toxicity to mouse fibroblasts. A key aspect of our methodology involved the use of a stereoscopic microscope for detailed monitoring of the wound closure process. Additionally, the distribution and potential systemic effects of the zinc and silver ions were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). This analysis was crucial in evaluating metal ion absorption through the wound site and estimating any toxic effects on the body. Our findings are particularly significant in the field of regenerative medicine. Transmission electron microscopy (TEM) revealed that the tested nanocomposites notably enhanced collagen deposition, a vital component in the wound healing process. Furthermore, a reduction in glycogen levels in hepatocytes was observed following treatment with these metal-protein dressings. This novel finding warrants further investigation. Overall, our findings highlight the diverse roles of zinc and silver nanocomposites in wound healing. This study not only contributes to our understanding of metal-protein complexes in tissue regeneration but also opens new avenues for research into the delivery mechanisms of such treatments for hard-to-heal wounds.

Functional nanocomposite-based printable inks impart strength, mechanical stability, and bioactivity to the printed matrix due to the presence of nanomaterials or nanostructures. Carbonaceous nanomaterials are known to improve the electrical conductivity, osteoconductivity, mechanical, and thermal properties of printed materials. In the current work, we have incorporated carbon nanofiber nanoparticles (CNF NPs) into methacrylated gelatin (GelMA) to investigate whether the resulting nanocomposite printable ink constructs (GelMA-CNF NPs) promote cell proliferation. Two kinds of printable constructs, cell-laden bioink and biomaterial ink, were prepared by incorporating various concentrations of CNF NPs (50, 100, and 150 µg/mL). The CNF NPs improved the mechanical strength and dielectric properties of the printed constructs. The in vitro cell line studies using normal human dermal fibroblasts (nHDF) demonstrated that CNF NPs are involved in cell-material interaction without affecting cellular morphology. Though the presence of NPs did not affect cellular viability on the initial days of treatment, it caused cytotoxicity to the cells on days 4 and 7 of the treatment. A significant level of cytotoxicity was observed in the highly CNF-concentrated bioink scaffolds (100 and 150 µg/mL). The unfavorable outcomes of the current work necessitate further study of employing functionalized CNF NPs to achieve enhanced cell proliferation in GelMA-CNF NPs-based bioprinted constructs and advance the application of skin tissue regeneration.

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Gene therapy is an important tool for treating fetal diseases that allows for the delivery and integration of therapeutic genes into the genome of cells carrying mutations. Nanomolecules, like PAMAM dendrimers, have recently come into wider use for carrying vectors as they have several advantages over viral vectors. Namely, (1) tunable size and surface chemistry, (2) uniform size, (3) the ability to target specific tissues, and (4) the ability to carry large biomolecules and drugs. Recently, we demonstrated that 4th generation (G4) PAMAM dendrimer with a cystamine core and a non-toxic surface having 90% –OH and 10% –NH₂ groups (D-Cys) could cross the blood–brain barrier following injection into the bloodstream. In the current study, as a proof of concept, we delivered the dendrimers alone (D-Cys) tagged with Cy5.5 (D-Cys-cy5.5) to healthy pregnant C57BL/6J mice to determine the fate of these dendrimers in the pregnant mice as well as in the fetus. Systematic diffusion of the D-Cys-cy5.5 was evaluated on gestational day 17 (3 days after injection) using in vivo imaging. This revealed that the dendrimer was taken up into circulation and away from the injection site. Analysis of sections by fluorescence microscopy showed that D-Cys-cy5.5 was able to successfully cross the maternal blood–brain barrier. However, analysis of the fetal brains failed to detect dendrimers in the central nervous system (CNS). Instead, they appeared to be retained in the placenta. This is one of the first studies to analyze the distribution of surface-modified PAMAM dendrimer in the pregnant mouse and fetus following systemic injection.

A nanocomposite of CaO:MgAl₂O₄ was synthesized through a straightforward and cost-effective sol–gel method. The investigation of the novel CaO:MgAl₂O₄ nanocomposite encompassed an examination of its morphological and structural alterations, as well as an exploration of its photocatalytic activities and electrochemical characteristics. XRD analysis revealed a nanocomposite size of 24.15 nm. The band gap, determined through UV studies, was found to be 3.83 eV, and scanning electron microscopy (SEM) illustrated flake-like morphological changes in the CaO:MgAl₂O₄ samples. TEM, HRTEM, and SAED studies of a CaO:MgAl₂O₄ nanocomposite would reveal important details about its morphology, crystallography, and nanostructure. Photocatalytic activity was quantified by studying the degradation of Acid Red-88 (AR-88) dye in a deionized solution, achieving a 70% dye degradation under UV irradiation in 120 min. Plant growth examinations were carried out using dye degraded water to test its suitability for agriculture. The electrochemical energy storage and sensing applications of the prepared nanocomposite were examined using CaO:MgAl₂O₄ modified carbon paste electrode through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In conclusion, the synthesized CaO:MgAl₂O₄ nanocomposite demonstrated promising morphological and structural characteristics, efficient photocatalytic activity, and potential applications in electrochemical energy storage, highlighting its versatility for various technological and environmental applications.

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