Plasmonic silver and gold nanoparticles: shape- and structure-modulated plasmonic functionality for point-of-caring sensing, bio-imaging and medical therapy

Multimodal sensing platform based on Fe3O4/DEX/PDA@Au(Raman reporters)@Au nanocomposites for sweat biomarkers monitoring

This paper introduces a highly sensitive and non-invasive Fe3O4/DEX/PDA@Au(Raman reporters)@Au (FDPA(Raman reporters)A) surface-enhanced Raman scattering (SERS) and colorimetric dual mode sensor. 5,5'- dithiobis (2-nitrobenzoic acid) (DTNB) was identified as the optimized Raman reporters in the FDPAA core-shell structures. To quantitative analysis of lactate and glucose captured from human sweat, we utilized magnet to enrich the FDPA(DTNB)A-lactate/glucose composites generated by the reaction. This design leverages the hydrophilic viscose fiber as microfluidic flow to concentrate analytes, substantially improving the detection sensitivity. This sensing platform reached noninvasive monitoring limits for glucose and lactate acid as 5 × 10-7 M and 10-6 M in sweat. This sensing platform responses to mutual-interfering, maintaining capacity, and bio-compatibility was estimated, expressing high reliable and precision. This FDPA(DTNB)A dual mode sensing platform shows easily manufacture, and great reliable and sensitivity, exhibiting vital potential for biosensor and medical research. The advancements are expected to encourage real utility of SERS-based sensing platform, hinting vast future application.

Small Au nanoparticles to be modified with decavanadate for sensitive and stable SERS detection

Surface enhanced Raman spectroscopy (SERS) has been a powerful vibrational optical spectroscopic technique for trace determination. And the application and promotion of SERS technology are closely related to plasmonic substrates. To combine the distinct electronic properties of polyoxovanadates with the plasmonic properties of Au NPs, the small cit-Au NPs (reduced by sodium citrate) was modified with decavanadate (V10) via ligand displacement. The structure of V10 was controlled by pH adjustment. X-ray photoelectron spectroscopy (XPS) and SERS were introduced for studying interactions of V10 with the surface of Au NPs. Compared with cit-Au NPs, V10-Au NPs owned higher absolute value of zeta potential and presented greater stability in CH3OH/H2O (V/V = 1:10) solvent environment. Even after 60 min of soaking, the V10-Au NPs still exhibited a typical coffee ring effect during the evaporation process with SERS enhancement. The stability of V10-Au NPs (in a solution with pH 4.8) was tested over a period of 5 days to indicate their ability to maintain SERS activity. Moreover, the V10-Au NPs also showed great sensitivity for cationic dye molecules and antibiotics, and the detection levels could be as low as μg⋅L-1. This study lays the foundation for the screening low-concentration cations in mixed solutions and monitoring the morphological changes of polyoxometalates during their application via SERS technology.

Point-of-use SERS approach for efficient detecting chlorfenapyr and emamectin benzoate residues based on Au trisoctahedrons@metal-organic framework modified on polya-mide 6 films

Health concerns over mixed pesticide residues highlight the need for rapid detection methods. This study developed a multifunctional point-of-use (POU) sensor that integrates separation, enrichment, and surface-enhanced Raman spectroscopy (SERS) using high-index Au trisoctahedrons (TOHs) and metal-organic frameworks (MOFs) on polyamide 6 (PA-6) film. The Au TOHs with sharp tips and high index facets offer excellent SERS performance, while MOFs facilitate analyte enrichment and separation. The flexible PA-6 film was used as an absorbent for the initial adsorption. Using the Au TOHs@ZIF-67/PA-6, we achieved on-site detection of chlorfenapyr (CFP) and emamectin benzoate (EB) in 5 min without pre-treatment, significantly faster than traditional methods. Detection limits were 0.68 ppb for CFP and 0.26 ppb for EB on cucumber surfaces, and 0.95 ppb and 0.13 ppb, respectively, in cucumber juice, well below tolerance levels. This method shows great promise for detecting pesticide mixtures in non-laboratory settings, offering a new POU alternative.

Designing potent plasmonic Ag/TiO2 nanohetero-phase junction for visible light driven photo-catalysis and anti-bacterial effect

In this study, we have reported the impact of well-grown Ag nanoparticles on TiO2 nanofiber mat, focusing the efficiency in anti-bacterial properties with ROS generation. Herein, the nanoheterostructure sample was achieved using electrospinning technique, followed by a solvothermal approach. The core focus was based on the effect of growth of Ag nanoparticles by varying the solvothermal time as well as the molar weight of Ag precursor against both the anti-bacterial property with gram-negative (e.g. E. coli) and another gram-positive (e.g. E. faecalis) bacterium. Prior to the detailed anti-bacterial test, the morphological analysis and the heterojunction formation was thoroughly investigated which showed the clear growth of Ag nanoparticles upon altering the experimental parameters via HRTEM analysis. The investigation showed that superior antibacterial activity was exhibited for the higher Ag loaded heterojunction samples whereas there showed no effect in the absence of Ag nanoparticles for TiO2 nanofibers. This is basically due to the presence of higher superoxide radicals in the nanoheterojunction materials, which is proved by a systematic study using the NBT degradation test under dark and visible light environment. Moreover, this phenomenon can be elucidated by the surface plasmon resonance effect in Ag nanoparticles, which when illuminated under visible light generates electrons and is transferred to the conduction band of TiO2. This transfer promotes the generation of reactive oxygen species (ROS), resulting in the exceptional antibacterial properties observed in AgT-10 ˃ AgT-5 ˃ AgT-2.5 ˃ TiO2NF.

Chiroptical hybrid nanomaterials based on metal nanoparticles and biomolecules

Chirality at the nanoscale has recently attracted renewed attention from the scientific community. As a result, various strategies have been proposed to develop chiral nanomaterials based on metal nanoparticles and chiral biomolecules such as DNA, amino acids, or proteins. We review herein the past and recent literature related to the functionalization of metal nanoparticles with various chiral biomolecules and their assembly into biomaterials with chiroptical response. We divide the review into two main parts, according to the class of biomolecules. We first discuss mechanisms employed to obtain chiral bioconjugates based on metal nanoparticles and amino acids or their derivatives (peptides and proteins), including mechanisms for chirality transfer from chiral biomolecules to achiral nanoparticles. We also review the use of amino acids/peptides as either chiral inducers for the growth of chiral nanoparticles or templates for the chiral arrangement of achiral nanoparticles. In the second part we present an overview of methods to prepare bioconjugates comprising DNA and metal nanoparticles, as well as selected examples of helical nanoparticle arrangements that employ DNA as a chiral template.

Pregnane X receptor attenuates gold nanoparticles' toxicity through accelerating zebrafish embryo hatching

It is well known that fish embryos are vulnerable to waterborne nanoparticles (NPs), with delayed hatching being the most common and sensitive endpoint. Up-regulation of hatching enzymes has been believed to be an important detoxification mechanism for NPs, but the inner mechanism for such phenomena has been seldom investigated. This study aimed to investigate the role of pregnane X receptor (Pxr) in maintaining the robustness of embryo hatching after treatment with gold nanoparticles (AuNPs, 4 and 82 nm). For this purpose, embryos from mating of 6-month-old wild-type (WT) AB strain zebrafish (Danio rerio, 3∼4-cm-length) were treated with AuNPs since 4 h post-fertilization (hpf). It was found that both AuNPs significantly inhibited embryo hatching after 52-h treatment, with Au-4 being more toxic at the same mass concentrations. At non-toxic concentrations and median effective concentrations (EC50) of delayed hatching, both AuNPs induced the mRNA expression of HEs and Pxr at 48 hpf, and Au-4 seemed to be more effective. The induction extents of HEs by AuNPs decreased when Pxr was knocked out or inhibited, indicating the role of Pxr in such process. Additionally, knockout/inhibition of Pxr significantly delayed the hatching of embryos at 56 hpf, and activation of Pxr accelerated the process at moderate concentrations. Such phenomena correlated well with the alterations in the mRNA expression and activities of HEs, indicating a fact that AuNPs activated Pxr and up-regulated HEs, which helped the detoxification of AuNPs. RNA-sequencing analysis of WT and pxr-deficient embryos at 24 hpf confirmed the alteration of he1.1&1.2. In addition, Pxr influenced mRNA encoding muscle development (muscle system process and striated muscle tissue development) and energy metabolism (carbohydrate metabolic process and ATP metabolic process), which were related to the motility of embryos and determined the hatching speed. Such function was confirmed by the reduced locomotor activity of pxr-deficient larvae at 120 hpf. Overall, these results suggested a novel role of Pxr in promoting the hatching of zebrafish embryos, which contributed to the detoxification of AuNPs.

From molecular mechanisms to clinical translation: Silk fibroin-based biomaterials for next-generation wound healing

Silk fibroin (SF) is a natural polymeric material that has attracted intense research attention in the field of wound healing due to its exceptional mechanical properties, tunable biodegradability, and multifunctional bioactivity. This review systematically summarizes the preparation strategies, functional modifications, and multidimensional application mechanisms of SF and its composite materials in wound healing. The innovative applications of SF in intelligent dressing design, immunometabolic regulation, controlled drug release, stem-cell function modulation, and bioelectrical-activity-mediated microenvironment remodeling is further explored, while analyzing the therapeutic efficacy and cost-effectiveness of SF through clinical translation cases. Distinct from previous reviews, this work not only integrates the latest advances in SF molecular mechanisms and material design but also emphasizes its potential in precision medicine, such as the development of genetically engineered SF for customized immunoregulatory networks. Finally, the article highlights the current challenges in the development of SF materials, including mechanical stability, degradation controllability, and standardization of large-scale production, and envisions future research directions driven by 3D bioprinting and synthetic biology technologies. This review provides a theoretical foundation and technical reference information for the development of efficient, multifunctional, and clinically translatable SF-based materials for application in wound healing.

Golden insights for exploring cancer: delivery, from genes to the human body using bimetallic Au/Ag nanostructures

Sweeping contact with cancer continues to rise globally, which has led to advanced research on new treatment approaches; nanotechnology has become crucial to targeted cancer therapy. Within the intimate of nanomaterials, Au/Ag nanostructures have emerged as highly attractive because of their distinctive desirable characteristics and their prospective roles in diagnosis as well as cancer therapy. The nanostructures developed revealed remarkable biocompatibility, optically recursive alteration, and magnificently improved therapeutic effects of gold and silver in conjunction with each other. This review addresses the molecular and systemic aspects of Au/Ag nanostructures in cancer research, including the impact of nanostructures on the molecular genetic pathways and their use of systemic administration in the human organism. We explain some of the related mechanisms of action, such as photothermal therapy (PTT), and photodynamic therapy (PDT), as well as the drug delivery systems where they display potential benefits towards offering a more targeted treatment approach with fewer side effects. The latest development has shown that they have the prospect of real-time imaging and biomarker identification, and owing to this they are being viewed as a tool for individualized treatment. However, there are still some limitations: challenges of scaling up, biological safety, and bringing it to the clinic. It is therefore incumbent upon these managements to overcome these hurdles to optimize for their impact. As a result, the current findings are briefly reviewed, and the development directions are discussed to support the revolutionary role of Au/Ag nanostructures in cancer research and therapy.

3D Self-Assembly of a Bilayer Nanoparticle Metasurface for Surface-Enhanced Raman Scattering (SERS) Sensing

Controllable periodic nanoparticle (NP) metasurfaces exhibit unique optical responses, which are crucial for applications in plasmonic sensing, photocatalysis, and nanoscale optical manipulation. Compared with monolayer NPs, bilayer NPs generate additional electromagnetic field localization effects between the layers, exhibiting enhanced light absorption and scattering. Here, we propose a novel method that assembles the monolayer NPs at a three-dimensional liquid-liquid interface (3D-LLI) into large-area two-dimensional bilayer NPs. This method not only allows for the construction of independent bilayer structures for fundamental research on metasurfaces but also enables the formation of "sandwich"-type interlayer structures for in situ SERS detection of both microparticle analytes such as polystyrene (PS), polyethylene terephthalate (PET), and poly(methyl methacrylate) (PMMA) and small molecules such as melamine, cysteine (Cys), and iminothiourazole (AMT).

Surface Charge Overrides Protein Corona Formation in Determining the Cytotoxicity, Cellular Uptake, and Biodistribution of Silver Nanoparticles

Silver nanoparticles (AgNPs) hold great promise in biomedical applications due to their unique properties and potential for specific tissue targeting. However, the clinical translation of nanoparticle-based therapeutics remains challenging, primarily due to an incomplete understanding of how nanoparticle properties influence interactions at the nano-bio interface, as well as the role of surface-adsorbed proteins (i.e., protein corona) in modulating nanoparticle-cell interactions. This study demonstrates that the surface charge has a greater influence than protein corona formation in determining the cytotoxicity, cellular uptake, and biodistribution of AgNPs. Using negatively and positively charged AgNPs, we show that while protein corona formation is essential for ensuring nanoparticle availability for cellular interactions, the adsorption of biomolecules is nonspecific and independent of surface charge. Conversely, the surface charge significantly influences the interactions of AgNPs with cells. Positively charged nanoparticles exhibit enhanced cellular uptake, preferential accumulation in lysosomes, and pronounced mitochondrial damage compared to their negatively charged counterparts, resulting in greater cytotoxic effects. This effect is particularly evident in human breast cancer cells, where negatively charged nanoparticles show minimal uptake and cytotoxicity. These findings demonstrate that surface charge is the primary factor governing nanoparticle-cell interactions rather than protein corona formation. Nonetheless, the protein corona plays a critical role in stabilizing nanoparticles in physiological environments.

Plasmonic coffee-ring biosensing for AI-assisted point-of-care diagnostics

A major challenge in addressing global health issues is developing simple, affordable biosensors with high sensitivity and specificity. Significant progress has been made in at-home medical detection kits, especially during the COVID-19 pandemic. Here, we demonstrated a coffee-ring biosensor with ultrahigh sensitivity, utilizing the evaporation of two sessile droplets and the formation of coffee-rings with asymmetric nanoplasmonic patterns to detect disease-relevant proteins as low as 3 pg/ml, under 12 min. Experimentally, a protein-laden droplet dries on a nanofibrous membrane, pre-concentrating biomarkers at the coffee ring. A second plasmonic droplet with functionalized gold nanoshells is then deposited at an overlapping spot and dried, forming a visible asymmetric plasmonic pattern due to distinct aggregation mechanisms. To enhance detection sensitivity, a deep neural model integrating generative and convolutional networks was used to enable quantitative biomarker diagnosis from smartphone photos. We tested four different proteins, Procalcitonin (PCT) for sepsis, SARS-CoV-2 Nucleocapsid (N) protein for COVID-19, Carcinoembryonic antigen (CEA) and Prostate-specific antigen (PSA) for cancer diagnosis, showing a working concentration range over five orders of magnitude. Sensitivities surpass equivalent lateral flow immunoassays by over two orders of magnitude using human saliva samples. The detection principle, along with the device, and materials can be further advanced for early disease diagnostics.

Artificial intelligence enhanced microfluidic system for multiplexed point-of-care-testing of biological thiols

Cysteamine (CA) serves as a cystine-depleting agent employed in the management of cystinosis and a range of other medical conditions. Monitoring blood CA levels at the point of care is imperative due to the risk of toxicity associated with elevated CA dosages. An additional significant challenge is presented by the intricate composition of human plasma and the presence of various interfering biological thiols, which possess similar structures or properties. Here, this work proposes an AI-enhanced Lab-on-a-disc system, also termed AI-LOAD, for multiplexed point-of-care testing of cysteamine. The AI-LOAD system incorporates an online whole blood separation mechanism alongside a naked-eye colorimetric detection module, facilitating the rapid and precise visual identification of cysteamine. Remarkably, the system necessitates only 40 μL of whole blood to analyze eight samples within 3-min, achieving a limit of detection as low as 10 μM, which is lower than the physiological toxic concentration of 0.1 mM. By leveraging diverse colorimetric responses generated through interactions between gold nanoparticles of varying sizes and different biological thiols, combined with artificial intelligence methodologies, the system successfully accomplished specific recognition of various biological thiols with 100 % accuracy. The proposed AI-LOAD will drive advancements in centrifugal microfluidics for point-of-care testing, thereby holding potential for broader applications in future biomedical research and in vitro diagnosis.

Integrative plasmonics: optical multi-effects and acousto-electric-thermal fusion for biosensing, energy conversion, and photonic circuits

Surface plasmons, a unique optical phenomenon arising at the interface between metals and dielectrics, have garnered significant interest across fields such as biochemistry, materials science, energy, optics, and nanotechnology. Recently, plasmonics is evolving from a focus on "classical plasmonics," which emphasizes fundamental effects and applications, to "integrative plasmonics," which explores the integration of plasmonics with multidisciplinary technologies. This review explores this evolution, summarizing key developments in this technological shift and offering a timely discussion on the fusion mechanisms, strategies, and applications. First, we examine the integration mechanisms of plasmons within the realm of optics, detailing how fundamental plasmonic effects give rise to optical multi-effects, such as plasmon-phonon coupling, nonlinear optical effects, electromagnetically induced transparency, chirality, nanocavity resonance, and waveguides. Next, we highlight strategies for integrating plasmons with technologies beyond optics, analyzing the processes and benefits of combining plasmonics with acoustics, electronics, and thermonics, including comprehensive plasmonic-electric-acousto-thermal integration. We then review cutting-edge applications in biochemistry (molecular diagnostics), energy (harvesting and catalysis), and informatics (photonic integrated circuits). These applications involve surface-enhanced Raman scattering (SERS), surface-enhanced infrared absorption (SEIRA), surface-enhanced fluorescence (SEF), chirality, nanotweezers, photoacoustic imaging, perovskite solar cells, photocatalysis, photothermal therapy, and triboelectric nanogenerators (TENGs). Finally, we conclude with a forward-looking perspective on the challenges and future of integrative plasmonics, considering advances in mechanisms (quantum effects, spintronics, and topology), materials (Dirac semimetals and hydrogels), technologies (machine learning, edge computing, in-sensor computing, and neuroengineering), and emerging applications (5G, 6G, virtual reality, and point-of-care testing).

Target-Zippable Anisotropic Near-Infrared AuNRs for Highly Reliable and Bright SERS Imaging of miRNA In Vivo

Near-infrared surface-enhanced Raman scattering (NIR-SERS) probes are promising for in vivo molecular imaging, but they face challenges in balancing plasmonic activity and signal reproducibility. We designed target-zippable anisotropic NIR gold nanorod (ani-NIR-AuNR) SERS probes, whose end and side regions are decorated with catalytic hairpin assembly (CHA) DNA hairpins and Raman reporters, respectively. These ani-NIR-AuNR monomers maintain a near-zero background until triggered by targets to form uniform side-by-side dimers with an average gap of 0.88 nm, synergistically amplifying electromagnetic enhancement and chemical enhancement. The CHA allows one target to zip numerous dimers, boosting hotspot density. These effects endow the SERS probes with good reproducibility (RSD = 8.56%), superior sensitivity (LOD = 0.15 fM), and a broad linear range (1 fM to 1 nM) for let-7d detection. Compared to fluorescence probes, they offer higher brightness, better spatial resolution, and longer signal persistence in in vivo miRNA imaging, demonstrating substantial potential in bioapplications.

Recent advances in smart gold nanoparticles for photothermal therapy

Gold nanoparticles (AuNPs) possess unique properties, including low toxicity and excellent optical characteristics, making them highly appealing for biomedical applications. The plasmonic photothermal effect of AuNPs has been explored to trigger localized hyperthermia. Four commonly explored gold nanoparticles (spheres, rods, stars, and cages) are produced and optimized to present the localized surface plasmon resonance effect in the near-infrared region, exploiting the increased penetration in the human body. Additionally, the production of hybrid AuNPs, combining them with other materials, such as silica, graphene, zinc oxide, polymers, and small molecules has been explored to amplify the photothermal effect (T ≥ 45ºC). This review provides an overview of AuNPs' application in photothermal therapy, describing the general synthesis processes and the main particle parameters that affect their application in photothermal therapy, including the hybrid nanomaterials. Associated with this rapid progress, surface functionalization can also improve colloidal stability, safety, and therapeutic outcomes. In this regard, we also highlight the emerging trend of applying cell-derived vesicles as biomimetic coatings, capable of evading immune recognition, increasing blood circulation, and targeting specific tissues. In addition, the challenges and future developments of AuNPs for accelerating the clinical translations are discussed in light of their therapeutic and theragnostic potential.

High-visual-resolution colorimetric immunoassay with attomolar sensitivity using kinetically controlled growth of Ag in AuAg nanocages and poly-enzyme-boosted tyramide signal amplification

Colorimetric enzyme-linked immunosorbent assays (CELISAs) have long been used for protein biomarker detection in diagnostics. Unfortunately, as confined by the monochromatic nature of detection signals and the limited catalytic activity of enzymes, CELISAs suffer from poor visual resolution and low sensitivity, hindering their effectiveness for early diagnostics in resource-limited settings. Herein, we report an ultrasensitive, high-visual-resolution CELISA (named PE-TSA-AuAg Cage-CELISA) that combines kinetically controlled growth of Ag in AuAg nanocages with poly-enzyme-boosted tyramide signal amplification (PE-TSA), enabling visual semiquantitative detection of protein biomarkers at attomolar levels with the naked eye. Specifically, the assay begins with the formation of sandwich-type immunocomplexes on a microplate in the presence of targets, and the labeled poly-horseradish peroxidases (poly-HRPs) initiate TSA, resulting in attaching numerous alkaline phosphatases (ALPs) on the microplate. The ALPs further catalyze ascorbic acid 2-phosphate to produce ascorbic acid, triggering the kinetically controlled growth of Ag inside AuAg nanocages. This process induces vivid multicolor variations spanning the visible spectrum range of 691∼477 nm, allowing for visual semiquantitation of protein biomarkers at ultralow levels without requiring specialized equipment. Using interleukin-12 as a model protein biomarker, we demonstrate that the PE-TSA-AuAg Cage-CELISA achieves a visual semiquantitative limit of detection (LOD) of 5 fg mL-1 (67 aM) and an instrumental quantitative LOD of 0.71 fg mL-1 (9.5 aM), representing an 853-fold improvement compared to the conventional HRP-based CELISA. Our findings suggest that the PE-TSA-AuAg Cage-CELISA has the potential to serve as an affordable and effective biosensing platform for early diagnostics in resource-limited settings.

Quantitative immunoassay of prostate-specific antigen dependent on SERS substrate of polymer-silver nanocubes modified with 4-mercaptobenzoic acid: The crucial effect of thiol molecule as internal standard

The early and reliable detection of prostate cancer remains a significant challenge in clinical diagnostics. This study presents a quantitative immunoassay for prostate-specific antigen (PSA) using a surface-enhanced Raman scattering (SERS) substrate comprised of polymer-silver nanocubes (Ag NCs) modified with 4-mercaptobenzoic acid (4MBA). We investigated the impact of thiol-containing internal standards (IS) on the quantitative accuracy of SERS, highlighting the superior stability of 4MBA compared to non-thiol molecules like crystal violet (CV). In contrast to CV, 4MBA exhibited significantly greater stability, with only a 9.3 % decrease in characteristic peak intensity after prolonged storage. Furthermore, the quantitative detection of PSA was realized using an IS-mediated sandwich immunostructure. Particularly, the coefficient of determination (R2) for the PSA standard calibration curve demonstrated remarkable enhancement from 0.987 to 0.994, highlighting the advantage of thiol-anchored IS correction strategy. Moreover, the limit of detection (LOD) for PSA was refined to 5.6 × 10-10 mg/mL after a perfect linear fitting was facilitated using 4MBA-based IS correction, which was superior to standard enzyme-linked immunosorbent assay (ELISA) and comparable SERS techniques. In addition, the specificity of the assay was confirmed by the lack of signal for non-target antigens. These findings demonstrate that the strategic selection of robust IS molecules can significantly enhance the quantitative capabilities of SERS technology, paving the way for its application in clinical diagnostics.

Comparative examination of the chemistry and biology of AI-driven gold NPs in Theranostics: New insights into biosensing, bioimaging, genomics, diagnostics, and therapy

Integrating artificial intelligence (AI) with nanomedicine is transforming Theranostics, driving advances in biosensing, bioimaging, genomics, diagnostics, and treatment. This review highlights the latest advancements in AI-driven nanomedicine, focusing on its transformative impact on healthcare. AI-integrated biosensors offer ultra-sensitive, real-time biomaterial detection, reducing false positives by 40 %. In bioimaging, AI algorithms improve resolution to 10 nm, particularly in gold nanoparticles (AuNP)-based imaging. AuNPs, leveraging surface plasmon resonance (SPR), act as contrast agents for early disease detection. AI accelerates genomic analysis, increasing sequencing accuracy by 30 %, enhancing biomarker identification for personalized medicine. AI powered diagnostics ensure rapid, non-invasive pathogen detection within 30 min with 95 % accuracy. AI-driven drug delivery systems enable precise, controlled release, reducing side effects by 20 %. This review explores AI-enhanced AuNPs in biosensing, bioimaging, genomics, diagnostics, and therapy while addressing challenges like scalability, biocompatibility. AI's role in Nanomedicine underscores its potential to revolutionize personalized medicine and future healthcare innovations.

Innovative applications of SERS in precision medicine: In situ and real-time live imaging

Surface-enhanced Raman scattering (SERS), a molecular spectroscopic technique with high sensitivity and specificity, has demonstrated groundbreaking potential in precision medicine in recent years. This review systematically summarizes recent advancements in SERS technology for in situ and real-time live imaging, focusing on its core value in early tumor diagnosis, intraoperative navigation, drug delivery monitoring, and dynamic pathological analysis. By optimizing nanoscale probe design-including targeted functionalization, enhanced biocompatibility, and integration with imaging systems-SERS overcomes the sensitivity and spatiotemporal resolution limitations of traditional imaging techniques, enabling precise capture and dynamic tracking of molecular events in live biological environments. The article further analyzes challenges in clinical translation, such as signal stability in complex biological environments, multimodal imaging coordination, and standardized data processing methods. Future directions for personalized therapy and intelligent integrated diagnostics are also discussed.

Pd@Au Nanoframe Hydrogels for Closed-Loop Wound Therapy

In this work, a multifunctional Pd@Au nanoframe hydrogel was designed to detect uric acid (UA) for in situ monitoring of wound infection and enhance wound healing by a chemo-photothermal strategy. In acidic conditions, the Pd@Au nanoframe hydrogels show high peroxidase-like activity by catalyzing H2O2 to produce reactive oxygen species (ROS) to damage RNAs of bacteria and enhance antibacterial activity. Under Near-infrared (NIR) laser irradiation, the Pd@Au nanoframe hydrogels exhibit photothermal conversion performance; i.e., the color of Pd@Au nanoframe hydrogel solution varies from deep blue (0 s, 25.4 °C) to red (300 s, 50.1 °C) in infrared thermography. After loading the antibacterial mupirocin (M), the as-obtained M Pd@Au nanoframe hydrogels show a maximum cumulative release rate exceeding 90% for mupirocin, as controlled by NIR laser irradiation. In antimicrobial experiments in vitro, M Pd@Au nanoframe hydrogels exhibit NIR laser-driven antibacterial ability; i.e., 98% Escherichia coli are effectively killed in 10 min. After coating rabbit wounds with a UA sensing patch of M Pd@Au nanoframe hydrogels, wound status can be monitored in real time by detecting UA concentration, leading to rapid wound healing in 4 days by a new synergistic effect of chemo-photothermal strategy. This approach successfully confirms a closed-loop strategy, i.e., real-time monitoring the status of a wound and efficiently perform chemo-photothermal wound therapy, for wound healing by combining functional hydrogels, NIR laser irradiation, and pharmaceutical antibacterials.

State-of-the-Art, Insights, and Perspectives for MOFs-Nanocomposites and MOF-Derived (Nano)Materials

Composite structures created from metal‒organic framework (MOF) matrices are reviewed in this work. Depending on the nature of the second component apart from the MOF platform, several synergistic properties may arise; at the same time, the initial features of the single constituent materials are usually maintained, and individual shortcomings are mitigated. Currently, timely energy and environmental challenges necessitate the quest for more advanced materials and technologies. Significant developments in MOF-nanocomposites have enabled their application across a wide range of modern and traditional fields. This review demonstrates in an exhaustive and critical way a broad range of MOF-based nanocomposites, namely, MOF/perovskite nanoparticles (NPs), MOF/metal (non-iron) oxide NPs, MOF/Fe3O4 NPs, MOF/metal chalcogenide NPs, MOF/metal NPs, and MOF/carbon-based materials, as well as nanocomposites of MOFs with other semiconductor NPs. Key points related to the synthesis, characterization, and applications of these materials are provided. Depending on their configuration, the composites under discussion can be applied in domains such as photoelectrochemical sensing, antibiotic/dye degradation, optoelectronics, photovoltaics, catalysis, solar cells, supercapacitors, batteries, water remediation, and drug loading. Sometimes, MOFs can undergo certain processes (e.g. pyrolysis) and act as precursors for composite materials with appealing characteristics. Therefore, a special section in the manuscript is devoted to MOF-derived NP composites. Toward the end of the text, we conclude while also describing the challenges and possibilities for further investigations in the umbrella of material categories analyzed herein. Despite the progress achieved, key questions remain to be answered regarding the relationships among the morphology, properties, and polyvalent activity of these materials. The present work aims to shed light on most of their aspects and innovative prospects, facilitating a deeper comprehension of the underlying phenomena, functionality, and mechanistic insights governing their behavior.

Gold-Coated Temperature Optical Fiber Sensor Based on a Mach-Zehnder Interferometer for Photovoltaic Monitoring

The development of a Mach-Zehnder interferometer based on tapered optical fiber for temperature sensing applications is presented. Two tapers, 24 mm apart, were fabricated on SMF-28e+ using the fusion splicer. The optical structures were coated with a 100 nm layer of gold. The influence of the gold deposition on the temperature sensitivity of the fabricated sensors is presented. The sensor was characterized in O-, S-, C-, and L-bands in a temperature range of 0-70 °C. The highest temperature sensitivity of 72 pm/°C with R2 = 0.9974 was obtained for the gold-coated sensor. During the investigation, the average transmission loss was low and did not exceed 7 dB.

Multifunctional dynamic chitosan-guar gum nanocomposite hydrogels in infection and diabetic wound healing

Traditional wound care methods are less effective for infectious and diabetic wounds, highlighting an urgent need for effective strategies. The study aimed to design a self-healing hydrogel with antibacterial, antioxidant, and photothermal capabilities to treat infectious and diabetic wounds. Silver nanoparticles (AgNPs) were loaded into mesoporous polydopamine (MPDA) nanoparticles to form Ag@MPDA nanoparticles. Ag@MPDA was incorporated into the cationic guar gum-chitosan-boric acid (CCB) hydrogel to obtain the PA-CCB hydrogel. PA-CCB hydrogel exhibited excellent self-healing and adhesive properties, adapting well to the dynamic wound environment. PA-CCB hydrogel combined with photothermal therapy (PTT) could effectively eradicated E. coli (99.9 %) and S. aureus (99.7 %). The PA-CCB hydrogel reduced excessive reactive oxygen species and promoted the migration of fibroblasts in vitro. In the infected mouse wound models, the PA-CCB hydrogel effectively inhibited bacteria. After combining with PTT, the antibacterial ability of the PA-CCB hydrogel was further enhanced. In the diabetic mouse wound models, the PA-CCB hydrogel reduced the inflammatory level of wound tissue. In both models, after combining with PTT, the PA-CCB hydrogel exhibited further improvements in angiogenesis, collagen deposition, and re-epithelialization. By integrating multifunctional hydrogel with PTT, the PA-CCB hydrogel exhibited broad application potential for infectious and diabetic wounds.

Field Detection of Multiple Infectious Diseases with Naked Eye Using Plasmonic-Enhanced Fluorescent Nanoparticles

Accurately diagnosing infectious diseases in a resource-limited setting is a major challenge. Plasmonic materials, via localized surface plasmon resonance (LSPR), have greatly enhanced fluorescence signal and detection sensitivity. However, traditional plasmonic-enhanced fluorescence methods largely rely on near-infrared or visible-light fluorophores with small Stokes shift, limiting naked-eye visibility without filters. In this study, we developed a novel plasmonic silver film (pSilverF) to enhance visible-light fluorescence with large Stokes shift, allowing for improved biomarker detection sensitivity under naked-eye observation. Integrated with bright fluorescent nanoparticles, we designed a multiplexed assay for detecting Hepatitis C Virus (HCV), Hepatitis B Virus (HBV), and Human Immunodeficiency Virus (HIV) antibodies, achieving detection sensitivities down to 0.0032, 0.023, and 0.168 NCU/mL, respectively. In a cohort of 68 clinical samples, our method achieved 100% sensitivity and specificity for HIV and HCV detection and 96% sensitivity and 100% specificity for HBV detection. Notably, the results can be visualized by the naked eye and directly captured by a standard mobile phone camera without any modification for signal analysis using RGB image splitting. This platform demonstrated potential for field detection of multiple infectious diseases with simple settings, providing a useful tool for disease control in communities and areas with limited medical resources.

Recent Advances in Food Safety: Nanostructure-Sensitized Surface-Enhanced Raman Sensing

Food safety is directly related to human health and has attracted intense attention all over the world. Surface-enhanced Raman scattering (SERS), as a rapid and selective technique, has been widely applied in monitoring food safety. SERS substrates, as an essential factor for sensing design, greatly influence the analytical performance. Currently, nanostructure-based SERS substrates have garnered significant interest due to their excellent merits in improving the sensitivity, specificity, and stability, holding great potential for the rapid and accurate sensing of food contaminants in complex matrices. This review summarizes the fundamentals of Raman spectroscopy and the used nanostructures for designing the SERS platform, including precious metal nanoparticles, metal-organic frameworks, polymers, and semiconductors. Moreover, it introduces the mechanisms and applications of nanostructures for enhancing SERS signals for monitoring hazardous substances, such as foodborne bacteria, pesticide and veterinary drug residues, food additives, illegal adulterants, and packaging material contamination. Finally, with the continuous progress of nanostructure technology and the continuous improvement of SERS technology, its application prospect in food safety testing will be broader.

DNA‑Directed Assembly of Photonic Nanomaterials for Diagnostic and Therapeutic Applications

DNA-directed assembly has emerged as a versatile and powerful approach for constructing complex structured materials. By leveraging the programmability of DNA nanotechnology, highly organized photonic systems can be developed to optimize light-matter interactions for improved diagnostics and therapeutic outcomes. These systems enable precise spatial arrangement of photonic components, minimizing material usage, and simplifying fabrication processes. DNA nanostructures, such as DNA origami, provide a robust platform for building multifunctional photonic devices with tailored optical properties. This review highlights recent progress in DNA-directed assembly of photonic nanomaterials, focusing on their applications in diagnostics and therapeutics. It provides an overview of the latest advancements in the field, discussing the principles of DNA-directed assembly, strategies for functionalizing photonic building blocks, innovations in assembly design, and the resulting optical effects that drive these developments. The review also explores how these photonic architectures contribute to diagnostic and therapeutic applications, emphasizing their potential to create efficient and effective photonic systems tailored to specific healthcare needs.

High-Efficiency SERS of 4-Mercaptobenzoic Acid and Biphenyl-4,4'-Dithiol via Nanoparticle-on-Mirror Plasmonic Nanocavities

Surface-enhanced Raman scattering (SERS) technology has important applications in many fields, such as biomedicine, environmental monitoring, and food safety. Plasmonic nanocavities have the ability to superdiffract localized light and enhance light-matter interactions. As a key SERS active substrate, research on plasmonic nanocavities has made significant progress regarding the enhancement mechanism, the utilization of hotspots for the detection of specific molecular groups, and practical applications. However, challenges related to improving the enhancement factor of nanocavity SERS, enhancing the stability and reproducibility of hotspots, and enabling the detection of single-molecule layers remain. In this study, we adopt a bottom-up approach to construct a silver microplate-molecule-multi-sized silver nanosphere nanoparticle-on-mirror (NPoM) nanocavity and achieve the efficient stable enhancement of Raman scattering from 4-mercaptobenzoic acid and biphenyl-4,4'-dithiol molecules via the electromagnetic mechanism. By characterizing the fabricated nanocavity using dark-field scattering and micro-confocal Raman scattering, we observed that the Raman scattering intensity in the NPoM nanocavity was enhanced by a factor of 103 compared to that of individual silver nanospheres. Furthermore, we achieved the efficient stabilization of SERS by precisely tuning the size of the silver nanospheres to match their resonance frequency with the Raman shift of the target molecules. This approach offers a valuable reference for the detection of various single-molecule layers and demonstrates significant potential for applications in biosensing and chemical analysis.

Plasmonic Biosensors in Cancer-Associated miRNA Detection

Cancer is one of the most lethal diseases and has distinct variants that affect over 60 organs in the human body. The necessity of advanced methodologies for the early diagnosis of cancer has grown over the past decades. Among various biomarkers, microRNAs (miRNAs) have emerged as highly specific and minimally invasive indicators for cancer detection, prognosis, and treatment monitoring. Their stability in biological fluids and their critical role in gene regulation make them valuable targets for diagnostic applications. Plasmonic biosensors have gained massive attention owing to their unique optical properties, such as surface plasmon resonance, making them promising tools for the sensitive and selective analysis of cancer-associated biomarkers. In contrast to previous reviews, this work offers a comprehensive overview of advancements from approximately the past five years, particularly in the detection of cancer-associated miRNAs. It emphasizes emerging plasmonic sensing strategies, integration with novel nanomaterials, and enhanced signal amplification techniques. By focusing on these recent innovations, this review provides new insights into the potential of plasmonic biosensors to improve cancer diagnosis and treatment.

Endogenous Protein-Modified Gold Nanorods as Immune-Inert Biomodulators for Tumor-Specific Imaging and Therapy

Engineered modifications of nanomaterials inspired by nature hold great promise for disease-specific imaging and therapies. However, conventional polyethylene glycol modification is limited by immune system rejection. The manipulation of gold nanorods (Au NRs) modified by endogenous proteins (eP@Au) is reported as an engineered biomodulator for enhanced breast tumor therapy. The results show that eP@Au NRs neither activate inflammatory factors in vitro nor elicit rejection of immune responses in vivo. Tumor-specific eP@Au NRs exhibit a dual-modal imaging capability and trigger a mild photothermal effect under near-infrared light irradiation, enabling highly efficient imaging and therapy of tumors. Transcriptome sequencing and confirmatory experiments reveal that the antitumor effect is mainly attributed to the repression of PI3K-Akt/MAPK signaling pathways at the molecular level. This powerful and surprising in situ eP-regulated biomodulation demonstrates the advantages of convenient fabrication, inert immunogenicity, and biocompatibility, providing an alternative strategy for biomedical imaging and therapy.

Hyperthermic Core-Shell Silver-Gold Nanoparticles: Green Synthesis and Adsorption-Uptake by Macrophages, Fibroblasts and Cancer Cells

Gold-coated silver nanoparticles (Ag@AuNPs) are synthesized by green synthesis using Vaccinium corymbosum as reducing agent. The obtained Ag@AuNPs present a core-shell structure with nanostar shape. The absorption spectrum of these nanoparticles shows a prominent band centred at 680 nm, within the optimal range for photothermal applications. Dispersions of Ag@AuNPs in water, 1.87 1010 NPs/mL, reach a temperature of 44.3 °C under laser excitation in 10 minutes, which is suitable for hyperthermia therapy. The internalization of Ag@AuNPs, at a concentration of 3 108 NPs/ml, by macrophages (Raw 264.7), human fibroblasts (Hs27), and cancer cells (4T1) is confirmed by transmission electron microscopy. Cytotoxicity studies demonstrate that at this concentration the cells are viable.

Redox-Sensitive Fluorescent Nanoparticles for Biovisualization of Malignant Tumors

Application of fluorescent redox-sensitive nanoparticles in current biomedicine ensures high sensitivity and accuracy of biovisualization. Nanoparticles are potent as they can long circulate in the blood, where the level of glutathione is relatively low, and are destroyed in tumor cells, releasing loaded dyes or drugs. The aim of the study was to develop new nanoparticles based on trithiocyanuric acid for biovisualization of malignant tumors and study capabilities of the developed nanoparticles.

Materials and Methods

Nanoparticles were obtained by polycondensation of trithiocyanuric acid using iodine. Scanning and transmission electron microscopy was used for their characterization, the loading of fluorescent dyes was assessed by means of spectrophotometry. Confocal laser scanning microscopy was applied to study the impact of nanoparticles on the viability of the 4T1 and A549 cell lines as well as their interaction with cells. The distribution of nanoparticles in tissues and organs of BALB/c model mice with grafted tumors was performed using fluorescence visualization.

Results

According to scanning microscopy, the size of the synthesized particles reached 100±20 nm. The adsorption isotherm demonstrated that adsorption of 0.27 mg of the RhB fluorescent dye per 1 mg of nanoparticles could be achieved. Enhanced release of the packed fluorescent dye was seen in the presence of glutathione and acetylcysteine. The particles did not significantly affect the viability of 4T1 and A549 cells. After intratumoral administration, they ensured a more intense fluorescent signal in the tumor area compared to a regular fluorescent dye solution.

Conclusion

The developed system of trithiocyanuric-acid-based nanoparticles demonstrated high efficiency in biovisualization of malignant tumors and has a potential for targeted delivery of treatment agents.

Kinetically Controlled Synthesis of Concave Five-Fold Twinned Gold Nanocrystals and Their Surface-Enhanced Raman Scattering Properties

The controllable synthesis of plasmonic metal nanocrystals with well-defined shapes is of great significance for their potential applications, and it requires a good understanding of the mechanism under thermodynamically and kinetically controlled reactions. Herein we present a seed-mediated growth approach to a series of five-fold twinned (FT) gold nanocrystals. Specifically, concave FT Au nanocrystals with embedded grooves at the twin boundaries are preferentially prepared under kinetically dominated conditions. Meanwhile, pentagonal bifrustums, truncated pentagonal bifrustums, truncated decahedrons, and decahedrons with high purity can be obtained by tailoring the deposition process. Therefore, reversible evolution between gold decahedrons and concave nanostructures was achieved by tuning the deposition modes. Importantly, concave FT Au nanocrystals display excellent surface-enhanced Raman scattering activities for 4-aminothiophenol due to their unique morphological characteristics. Our work provides an avenue for rational synthesis of FT gold nanostructures with tunable shapes and will promote their potential applications in plasmonics and catalysis.

Recent advances in photothermal nanomaterials for ophthalmic applications

The human eye, with its remarkable resolution of up to 576 million pixels, grants us the ability to perceive the world with astonishing accuracy. Despite this, over 2 billion people globally suffer from visual impairments or blindness, primarily because of the limitations of current ophthalmic treatment technologies. This underscores an urgent need for more advanced therapeutic approaches to effectively halt or even reverse the progression of eye diseases. The rapid advancement of nanotechnology offers promising pathways for the development of novel ophthalmic therapies. Notably, photothermal nanomaterials, particularly well-suited for the transparent tissues of the eye, have emerged as a potential game changer. These materials enable precise and controllable photothermal therapy by effectively manipulating the distribution of the thermal field. Moreover, they extend beyond the conventional boundaries of thermal therapy, achieving unparalleled therapeutic effects through their diverse composite structures and demonstrating enormous potential in promoting retinal drug delivery and photoacoustic imaging. This paper provides a comprehensive summary of the structure-activity relationship between the photothermal properties of these nanomaterials and their innovative therapeutic mechanisms. We review the latest research on photothermal nanomaterial-based treatments for various eye diseases. Additionally, we discuss the current challenges and future perspectives in this field, with a focus on enhancing global visual health.

Tumor-Homing Biomimetic Near-Infrared II SERS Probes for Targeted Intraoperative Resection Guidance of Orthotopic Glioblastoma

In vivo optical imaging holds great potential for surgical guidance with the ability to intraoperatively identify tumor lesions in a surgical bed and navigate their surgical excision in real time. Nevertheless, its full potential remains underexploited, mainly due to the dearth of high-performance optical probes. Herein, hybrid cell membrane-biomimetic near-infrared II surface-enhanced Raman spectroscopy (NIR-II SERS) probes are reported for intraoperative resection guidance of orthotopic glioblastoma. A novel class of plasmonic Au nanorod (AuNR)@Au-Ag frames is developed with remarkable plasmonic properties tunable beyond 1700 nm. We demonstrate the exceptional NIR-II SERS performance both in vitro and in vivo of the biomimetic NIR-II SERS probes created with AuNR@Au-Ag frames and hybrid cell membranes. The biomimetic NIR-II SERS probes are successfully applied in an orthotopic glioblastoma mouse model for intraoperative resection guidance with complete tumor removal and improved surgical outcomes. This study presents a promising strategy for precise NIR-II SERS surgical navigation.

Photonic Nanomaterials for Wearable Health Solutions

This review underscores the transformative potential of photonic nanomaterials in wearable health technologies, driven by increasing demands for personalized health monitoring. Their unique optical and physical properties enable rapid, precise, and sensitive real-time monitoring, outperforming conventional electrical-based sensors. Integrated into ultra-thin, flexible, and stretchable formats, these materials enhance compatibility with the human body, enabling prolonged wear, improved efficiency, and reduced power consumption. A comprehensive exploration is provided of the integration of photonic nanomaterials into wearable devices, addressing material selection, light-matter interaction principles, and device assembly strategies. The review highlights critical elements such as device form factors, sensing modalities, and power and data communication, with representative examples in skin patches and contact lenses. These devices enable precise monitoring and management of biomarkers of diseases or biological responses. Furthermore, advancements in materials and integration approaches have paved the way for continuum of care systems combining multifunctional sensors with therapeutic drug delivery mechanisms. To overcome existing barriers, this review outlines strategies of material design, device engineering, system integration, and machine learning to inspire innovation and accelerate the adoption of photonic nanomaterials for next-generation of wearable health, showcasing their versatility and transformative potential for digital health applications.

Localized surface plasmon resonance sensing based on monometallic gold nanoparticles: from material preparation to detection of bioanalytes

The tunable geometrical properties of gold nanoparticles (AuNPs) endow them with the capacity to exhibit distinct behaviors with respect to both macroscopic (color) and microscopic (resonance wavelength) aspects, which has been extensively utilized in localized surface plasmon resonance (LSPR) sensing platforms. Additionally, functionalizing AuNP surfaces enhances the platforms' capabilities, allowing for the detection of a wide range of molecules related to various aspects of human health. In this review, we comprehensively elucidate the fundamental principles of LSPR biosensing and provide an in-depth survey of the preparation processes for metal nanoparticles, encompassing deposition technology for large-scale particle production as well as ion reduction methods that afford superior control over the particles' physical and chemical attributes. The sensing strategies based on adjustment of the dielectric environment and particle dispersion-aggregation levels are thoroughly reviewed and discussed. The discussion focused on a specific class of nanoparticles, characterized by their uniform shape and size, with each section bifurcated into two parts: a summary of the salient features and recent discoveries pertaining to the sensing strategy, as well as illustrations of representative, cutting-edge applications employing the strategy. We specifically aim to scrutinize analytes commonly encountered in the biomedical realm, encompassing biomarkers that serve as indicators of a wide range of diseases and microbial pathogens, while also prognosticating the future development trends of LSPR optical biosensor platforms within the biomedical field.

Surface-Enhanced Raman Spectroscopy for Nitrite Detection

Nitrite is an important chemical intermediate in the nitrogen cycle and is ubiquitously present in environmental and biological systems as a metabolite or additive in the agricultural and food industries. However, nitrite can also be toxic in excessive concentrations. As such, the development of quick, sensitive, and portable assays for its measurement is desirable. In this review, we summarize the working principles and applications of surface-enhanced Raman spectroscopy (SERS) as a rapid, portable, and ultrasensitive method for nitrite detection and showcase its applicability in various water, food, and biological samples. The challenges and opportunities for future developments are also discussed.

Plasmon-Enhanced Fluorescence Paper Lateral Flow Strip for Point-of-Care Testing of SARS-CoV-2 Antigens

Currently commercial colorimetric paper lateral flow immunoassays exhibit insufficient limit of detection (LOD) and limited clinical sensitivity toward the detection of SARS-CoV-2 antigens, which causes a high false negative rate. To mitigate this issue, a new plasmon-enhanced fluorescence probe was developed for paper lateral flow strips (PLFSs). The probe is made of a sandwich-structured Ag-core@silica@dye@silica-shell nanoparticle in which fluorescent dyes are sandwiched between the plasmonic Ag core and the silica outer shell, and the separation distance between the Ag core and the dye molecules is controlled by the silica space layer. At the optimal thickness of the silica space layer, plasmons can amplify fluorescence signals via the Purcell effect. The PLFS with the optimized plasmonic fluorescence probes exhibits a LOD of 65.0 pg/mL toward detection of the SARS-CoV-2 nucleocapsid protein in a buffer solution, which is much lower than that (2.3 ng/mL) of the commercial colorimetric counterpart. Furthermore, it has been used successfully for testing COVID-19 clinical samples, which has achieved 100% clinical sensitivity and 94.2% specificity, while the commercial colorimetric PLFS exhibits 75.7% sensitivity and 91.4% specificity. The results demonstrate that the plasmonic fluorescence PLFS can reduce false negative results significantly. This device has great potential in helping with timely medical intervention and prevention from COVID-19 transmission.

Comparison of Microfluidic Synthesis of Silver Nanoparticles in Flow and Drop Reactors at Low Dean Numbers

This study evaluates the performance of continuous flow and drop-based microfluidic devices for the synthesis of silver nanoparticles (AgNPs) under identical hydrodynamic and chemical conditions. Flows at low values of Dean number (De < 1) were investigated, where the contribution of the vortices forming inside the drop to the additional mixing inside the reactor should be most noticeable. In the drop-based microfluidic device, discrete aqueous drops serving as reactors were generated by flow focusing using silicone oil as the continuous phase. Aqueous solutions of reagents were supplied through two different channels merging just before the drops were formed. In the continuous flow device, the reagents merged at a Tee junction, and the reaction was carried out in the outlet tube. Although continuous flow systems may face challenges such as particle concentration reduction due to deposition on the channel wall or fouling, they are often more practical for research due to their operational simplicity, primarily through the elimination of the need to separate the aqueous nanoparticle dispersion from the oil phase. The results demonstrate that both microfluidic approaches produced AgNPs of similar sizes when the hydrodynamic conditions defined by the values of De and the residence time within the reactor were similar.

Enhancing photovoltaic efficiency in Half-Tandem MAPbI3/ MASnI3 Perovskite solar cells with triple core-shell plasmonic nanoparticles

Significant progress has been made through the optimization of modelling and device architecture solar cells has proven to be a valuable and highly effective approach for gaining a deeper understanding of the underlying physical processes in solar cells. Consequently, this research has conducted a two-dimensional (2D) perovskite solar cells (PSCs) simulation to develop an accurate model. The approach utilized in this study is based on the finite element method (FEM). Initially, a new configuration was introduced by incorporating a CH3NH3SnI3 layer as the absorber within the PSC structure, forming a parallel architecture. As a result, the power conversion efficiency (PCE) of PSC increased up to 26.89%. The light trapping process plays an essential role in enhancing the performance of PSCs. For this purpose, we utilized arrays of metal nanostructures on the active layer (AL) which resulted in significantly enhancing light absorption within these layers. In this research, the influence of nanoparticles position within the AL, the radius of nanoparticles and their composition (gold (Au) and silver (Ag)) on enhancing absorption in PSCs are examined by determining the cross-sectional area of light scattering and absorption on Au and Ag nanoparticles. The optimal position for the plasmonic nanoparticles was determined to be inside the MASnI3 as the complementary AL, 60 nm for the radius and Ag as champion composition. As a result of these modifications, the PCE reached 29.52%, representing an approximate 64% improvement compared to the planar structure. Subsequently, dielectric-metal-dielectric nanoparticles were introduced into the MASnI3 layer, replacing the previously embedded metallic nanoparticles, in order to enhance their chemical and thermal stability. According to optical-electrical simulation results, the short-circuit current density (Jsc) of the proposed parallel PSC, featuring triple core-shell nanoparticles composed of TiO2@Ag@TiO2 and SiO2@Ag@SiO2, has been improved by approximately 40% and 41.5%, respectively, compared to a PSC lacking nanoparticles. Moreover, under optimal conditions for the PSC, the open-circuit voltage (Voc), Jsc, fill factor (FF), and PCE were simulated at 1.01 V, 35.17 mA/cm², 84.16, and 30.18%, respectively. This approach paves the way for advancements in the development of perovskite solar cells, offering significant potential for practical applications and enhanced efficiency.

Enhanced Structure Stability of Au Nanobipyramids by an In Situ Customized Silver Armor

Revealing the structure stability and evolution of gold nanocrystals at the atomic scale is crucial to their versatile applications; however, the fundamental mechanism remains elusive due to the lack of in situ characterizations. In this work, the structural evolution of two types of Au nanobipyramids (Au NBPs) at elevated temperatures is monitored through in situ electron microscopy analysis, and there is a sharp distinction between their structure stability despite that they possess the same crystalline structure. Detailed material characterization reveals that the surface alloying of residual Ag with Au (customized Ag armor) can greatly inhibit the Au atom diffusion and contribute remarkably to the stability and surface-enhanced Raman scattering improvement. Moreover, the structure of the Au NBPs is further enhanced when the vulnerable tips are selectively coated with an oxide shell (Cu2O) to form a dumbbell-shaped nanostructure, which would undergo a completely different structure evolution at elevated temperatures.

Spectroscopic approach to optimize the biogenic silver nanoparticles for photocatalytic removal of ternary dye mixture and ecotoxicological impact of treated wastewater

The fabricating of extremely effective, economical, ecologically safe, and reusable nanoparticle (NP) catalysts for the removal of water pollution is urgently needed. This study, spectroscopically optimizes the process parameters for the biogenic synthesis of AgNP catalysts using Cledrdendrum infortunatum leaf extract. The optimization of several synthesis parameters was systematically studied using UV-Vis spectroscopy to identify the ideal conditions for AgNPs formation. The AgNPs are spherical with a size of ~ 20 nm, pure and stable. Mechanistic insights into the biogenic synthesis process were explored. The photocatalytic performance of biogenic AgNPs was evaluated for the degradation of three common (crystal violet, thioflavin T, and methylene blue) dyes as models in ternary mixtures under the influence of sunlight. AgNPs show excellent photocatalytic efficiency in terms of degradation percentage (82.89-96.96% within 110 min), kinetics (0.0247-0.0331 min-1), half-life (20.96-28.11 min), and T80 (48.67-65.28 min) and also easily recovered and reused. Ecological safety assessment of the treated wastewater was assessed on the growths of rice, mustard, and lentil plants, and preliminary findings demonstrated that seedling growths for treated wastewater were nearly similar to the control sample but retarded in dye-contaminated wastewater suggesting potential use of treated wastewater for sustainable agriculture without compromising ecological balance. So, this study explores biogenic AgNPs as cost-effective, safe, and sustainable photocatalytic agents for the remediation of hazardous mix dyes and real-life applications of treated water for agricultural purposes.

Multi-responsive shape memory and self-healing hydrogels with gold and silver nanoparticles

Nanocomposite smart gels (Nc-x) with self-healing and shape memory properties were designed in different types and size nano particles with temperature or light stimuli. Nc-x networks were prepared by bulk polymerization of stearyl methacrylate (SM) and vinyl pyrrolidone (VP) in the presence of gold and silver nanoparticles. The structure, which does not contain any chemical cross-linkers, is held together by hydrophobic interactions while consisting of dipole-dipole bonds of the VP units and long alkyl groups in the side chains of the SM. Thanks to their crystalline regions, shape memory gels can self-heal with the presence of long hydrophobic chains, and furthermore, the nanoparticles (NPs) incorporated into the structure facilitate the controlled tuning of hydrophilic and hydrophobic properties. Nc-x gels have the ability to self-heal by repairing mechanical damage independently or in the presence of a stimulus, as well as transforming from a temporary form to a permanent form. In vitro experiments on human skin fibroblast cells revealed that cell viability was over 100% after 48 hours and almost complete recovery was observed in scratch experiments at the end of this period. Based on the results obtained, Nc-x gels have been shown to have the potential to be used as a non-invasive wound dressing material alternative to traditional wound closure methods.

Biobased Polymers Enabling the Synthesis of Ultralong Silver Nanowires and Other Nanostructures

Conventional polyol synthesis of silver nanowires has exclusively relied on polyvinylpyrrolidone (PVP), a nonbiodegradable polymer with no viable alternatives. The underlying reaction mechanism remains unclear. Herein, we discovered a new sustainable solution by employing biobased cellulose derivatives, including hydroxyethyl cellulose (HEC), as effective substitutes for PVP. Under mild reaction conditions (125 °C, ambient pressure), HEC facilitates the growth of ultralong silver nanowires (>100 μm) from penta-twinned silver seeds through a four-stage kinetic process. Theoretical calculations further reveal that HEC is physiosorbed onto the silver surfaces, while the presence of bromide ions (Br-) facilitates the evolution of seeds into nanowires. By varying halide ion concentrations and substitution in different cellulose derivatives, we successfully synthesized silver nanostructures with additional intriguing morphologies, including quasi-spherical nanoparticles, bipyramids, and nanocubes. Furthermore, transparent conductive films fabricated from ultralong silver nanowires synthesized with HEC demonstrated superior performance compared to those made with PVP-synthesized nanowires.

Recent advances of photoresponsive nanomaterials for diagnosis and treatment of acute kidney injury

Non-invasive imaging in the near-infrared region (NIR) offers enhanced tissue penetration, reduced spontaneous fluorescence of biological tissues, and improved signal-to-noise ratio (SNR), rendering it more suitable for in vivo deep tissue imaging. In recent years, a plethora of NIR photoresponsive materials have been employed for disease diagnosis, particularly acute kidney injury (AKI). These encompass inorganic nonmetallic materials such as carbon (C), silicon (Si), phosphorus (P), and upconversion nanoparticles (UCNPs); precious metal nanoparticles like gold and silver; as well as small molecule and organic semiconductor polymer nanoparticles with near infrared responsiveness. These materials enable effective therapy triggered by NIR light and serve as valuable tools for monitoring AKI in living systems. The review provides a concise overview of the current state and pathological characteristics of AKI, followed by an exploration of the application of nanomaterials and photoresponsive nanomaterials in AKI. Finally, it presents the design challenges and prospects associated with NIR photoresponsive materials in AKI.

Rapid Size Determination of Quasispherical Gold Nanoparticles by Electrocatalysis Efficiency-Regulated Electrochemiluminescence

The size of gold nanoparticles (AuNPs) largely decides their properties and applications, making the rapid screening of AuNP size important. Despite the fact that AuNP-amplified electrochemiluminescence (ECL) is widely used in various ECL sensing applications, the mechanism of ECL enhancement remains elusive, especially the quantitative relationship between the enhanced ECL intensity and the size of AuNPs. In this work, taking quasispherical and citrate-stabilized AuNPs as model nanoparticles, we have reported that the ECL intensity of the S2O82--O2 system enhanced significantly with the increasing AuNP size. AuNPs acted as bielectrocatalysts for reducing the S2O82- and O2. The further study of enhancement mechanism demonstrates that AuNPs with increasing size facilitate the electron transfer and promote the generation of radicals required for the ECL emission, which produces more emitters-singlet oxygen. Meanwhile, the high surface density of citrate on small AuNPs suppresses the ECL signal by forming an electrostatic barrier. On the basis of the above phenomena, an ECL-based rapid AuNP size screening approach has been established. The accuracy of this platform is verified by the consistent results in comparison to transmission electron microscopy (TEM) measurements. This work not only provides deep insight into the correlation between the AuNP size and the ECL enhancement but also contributes an alternative to the TEM technique for the rapid AuNP size screening. Additionally, this study also extends the exploration of ECL-based structure analysis techniques toward nanomaterials through clarifying the structure-electrocatalytic activity correlation.

Engineering in situ growth of Au nanoclusters on hydrophilic paper fibres for fluorescence calligraphy-based chemical logic gates and information encryption

Gold nanoclusters (AuNCs) are a type of rising-star fluorescence nanomaterials, but their properties and applications are hindered by the multi-step synthesis and purification routes, as well as the lack of desired supporting substrates. To enhance optical performance and working efficiency, the synthesis and applications of AuNCs are suggested to be merged with emerging substrates. Herein, glutathione-modified hydrophilic rice papers are incubated in chloroauric acid aqueous solutions, and the oxidation-reduction reaction between glutathione and Au ions enables the in situ formation of fluorescent AuNCs on the solid fibres of rice papers. The in situ growth of fluorescent AuNCs on rice papers resulted in eye-catching fluorescence tracks, similar to traditional Chinese conventional calligraphy; thus, this fluoresence calligraphy is defined in this work. The entire process, including synthesis and signal responses, is extremely simple, rapid, and repeatable. Moreover, the diversity of additive chemical reagents in the studied rice papers resulted in responsive fluorescence calligraphy, and the as-synthesized AuNC materials exhibited high reliability and optical stability. Significantly, with the integration of synchronous formation and application of Au nanoclusters on hydrophilic paper substrates, high-performance logical gates and information encryption systems were constructed, remarkably facilitating the progress of molecular sensing and important information transmission.

Engineered M13-Derived Bacteriophages Capable of Gold Nanoparticle Synthesis and Nanogold Manipulations

For years, gold nanoparticles (AuNPs) have been widely used in medicine and industry. Although various experimental procedures have been reported for their preparation and manipulation, none of them is optimal for all purposes. In this work, we engineered the N-terminus of the pIII minor coat protein of bacteriophage (phage) M13 to expose a novel HLYLNTASTHLG peptide that effectively and specifically binds gold. In addition to binding gold, this engineered phage could synthesize spherical AuNPs of 20 nm and other sizes depending on the reaction conditions, aggregate them, and precipitate gold from a colloid, as revealed by transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM), as well as ultraviolet-visible (UV-vis) and Fourier-transform infrared (FTIR) spectroscopic methods. We demonstrated that the engineered phage exposing a foreign peptide selected from a phage-displayed library may serve as a sustainable molecular factory for both the synthesis of the peptide and the subsequent overnight preparation of AuNPs from gold ions at room temperature and neutral pH in the absence of strong reducing agents, such as commonly used NaBH4. Taken together, the results suggest the potential applicability of the engineered phage and the new, in vitro-identified gold-binding peptide in diverse biomimetic manipulations.

Tutorial on Describing, Classifying, and Visualizing Common Crystal Structures in Nanoscale Materials Systems

Crystal structures underpin many aspects of nanoscience and technology, from the arrangements of atoms in nanoscale materials to the ways in which nanoscale materials form and grow to the structures formed when nanoscale materials interact with each other and assemble. The impacts of crystal structures and their relationships to one another in nanoscale materials systems are vast. This Tutorial provides nanoscience researchers with highlights of many crystal structures that are commonly observed in nanoscale materials systems, as well as an overview of the tools and concepts that help to derive, describe, visualize, and rationalize key structural features. The scope of materials focuses on the elements and their compounds that are most frequently encountered as nanoscale materials, including both close-packed and nonclose-packed structures. Examples include three-dimensionally and two-dimensionally bonded compounds related to the rocksalt, nickel arsenide, fluorite, zincblende, wurtzite, cesium chloride, and perovskite structures, as well as layered perovskites, intergrowth compounds, MXenes, transition metal dichalcogenides, and other layered materials. Ordered versus disordered structures, high entropy materials, and instructive examples of more complex structures, including copper sulfides, are also discussed to demonstrate how structural visualization tools can be applied. The overall emphasis of this Tutorial is on the ways in which complex structures are derived from simpler building blocks, as well as the similarities and interrelationships among certain classes of structures that, at first glance, may be interpreted as being very different. Identifying and appreciating these structural relationships is useful to nanoscience researchers, as it allows them to deconstruct complex structures into simpler components, which is important for designing, understanding, and using nanoscale materials.

SERS detection of thiram using a 3D sea cucumber-like composite flexible porous substrate

Nowadays, trace detection of thiram is in urgent demand due to its widespread application in agriculture and significant harmful effects on public health. In this work, a three-dimensional (3D) sea cucumber-like flexible porous surface-enhanced Raman scattering (SERS) substrate composed of a poly(vinylidene fluoride) (PVDF) membrane, ZnO nanorods, gold films, and Ag nanoparticles (Ag/Au/ZnO/P) has been established for the highly sensitive detection of thiram. The substrate takes advantage of the 3D morphology of the Ag/Au/ZnO system on a flexible porous PVDF membrane to produce abundant plasmonic hot spots. Meanwhile, the employment of an AgNPs/Au shell system combined the benefits of both gold and silver metals, thus guaranteeing stable and sensitive detection. With 4-mercaptobenzoic acid (4-MBA) as a probe molecule, the Ag/Au/ZnO/P substrate exhibited excellent linear detection in the range of 10-11-10-5 M, with a correlation coefficient (R2) of 0.99 and an enhancement cofactor of 7.09 × 107. The substrate exhibited excellent uniformity with a related standard deviation (RSD) value of 3.82% and demonstrated high stability during a 15 d-storage test. In addition, the substrate could detect thiram in an aqueous solution at concentrations as low as 10-10 M with excellent selectivity. Meanwhile, thiram on the surface of apple peel could be easily detected by the Ag/Au/ZnO/P substrate with the "paste-and-peel" method in less than 10 s, and the detection limit could be as low as 0.48 ng cm-2. Overall, the remarkable performance of the Ag/Au/ZnO/P SERS substrate demonstrated its great potential for the environmental monitoring of thiram.