• Optical fibre LSPR sensor optimised by comparing AuNP deposition times. • Maximum sensitivity (257 nm/RIU) and strong linearity (R 2 = 0.99) achieved with 1-hour AuNP immersion. • Sensor demonstrated excellent reproducibility, repeatability, and stability. • Findings support the rational design of low-cost fibre-tip biosensors for detection of TNF-α with LoD of 5.86 pg/mL. This research explores the development and refinement of a localised surface plasmon resonance (LSPR) biosensor using gold nanoparticles (AuNPs) for enhanced biomarker detection. The study aims to address the challenge of cost-effective fabrication while achieving high sensitivity, with a focus on optimising the AuNP deposition process on an optical fibre’s end face. The biosensor was constructed using a silane-based method, particularly aminosilanisation, allowing AuNPs to attach to the fibre’s tip surface. Different deposition times were tested, ranging from 1 to 6 h, to determine their impact on the sensor’s sensitivity to refractive index changes. The findings revealed that the 1-hour deposition time yielded the optimal balance of sensitivity (257.05 nm/RIU) and linearity (R2 = 0.9917). In contrast, longer deposition times led to reduced effectiveness due to excessive binding of AuNPs and reduced spatial separation between them. The sensor demonstrated excellent reproducibility, repeatability and stability. Beyond refractive index sensing, we further functionalised the sensor and successfully demonstrated its ability to detect tumour necrosis factor-alpha (TNF-α), a key inflammatory biomarker, with a clinically relevant limit of detection (LoD) of 5.86 pg/ml. This optimised LSPR biosensor platform demonstrates strong potential for future development towards cytokine detection in clinical settings.

The accurate and non-invasive detection of dopamine (DA) in sweat is crucial for the early diagnosis of neurological diseases, but the selective and sensitive detection of DA in complex biological matrices still remains a challenge. This study presents a novel screen-printed electrode based on a ternary nanocomposite of gold nanobipyramid@copper selenide@MXene nanosheets (Au NBP@Cu2-xSe@MXene) for the highly sensitive and selective detection of DA. For the first time, Au NBPs with localized surface plasmon resonance (LSPR) in the near-infrared second window (NIR-II) are employed to enable a one-step, pretreatment-free detection strategy by leveraging the negligible background absorption of biological matrices. Under NIR-II irradiation, the Au NBP core generates an LSPR-induced photothermal effect, which can be harnessed by the Cu2-xSe shell to generate a thermoelectric field that significantly accelerates the interfacial electrocatalytic oxidation of DA. Besides, Au NBPs can generate LSPR hot carriers, which are injected into Cu2-xSe to participate in the redox process. Furthermore, the MXene substrate ensures efficient charge transport and structural stability. As a result, this ternary nanocomposite-based sensor exhibits a wide linear detection range for DA from 0.1 to 1000 μM. It achieves a detection limit of 0.107 μM under standard conditions, which is further reduced to 0.068 μM under NIR-II laser irradiation, demonstrating the effective signal amplification via photothermal-thermoelectric coupling. This work provides a robust and innovative material platform that integrates photothermal, thermoelectric, and electrochemical mechanisms, paving the way for the development of next-generation, high-performance wearable sensors for non-invasive health monitoring.

Multiplexed biosensing: A review of surface plasmon resonance platforms for biomarker analysis.

Label-free naked-eye aptasensor for detection of Cytochrome c- mediated apoptosis drug screening.

AuAg-PTCA bimetallic Schottky junction with high photoelectric conversion efficiency for ultrasensitive photoelectrochemical analysis of environmental pollutant cadmium ion.

Metal nanoparticle-mediated photothermal therapy for bacterial eradication: Mechanisms, strategies, and clinical challenges.

Enhancing localized surface plasmon resonance effects via NiCo electronic structure modulation for efficient low-temperature photothermal CO2 methanation

We propose a novel, highly sensitive light-induced thermoelastic spectroscopy (LITES) detection scheme based on a quartz crystal tuning fork (QCTF), which features a dual enhancement mechanism driven by the localized surface plasmon resonance (LSPR) effect. Leveraging the inherent thermoelastic and piezoelectric effects of the QCTF, a thin layer of tailor-designed gold nanorods (AuNRs) was deposited onto the central region of the tuning fork. The dual synergistic enhancement and coupling effects originating from the LSPR response and superior thermal conductivity of AuNRs substantially improve the light absorption efficiency of the QCTF, which in turn gives rise to the enhanced sensitivity of gas detection. In this study, we first systematically investigated the LSPR mechanism of AuNRs and further synthesized AuNRs with tailored aspect ratios using the seed-mediated growth method. Subsequently, a full LITES detection system based on the AuNRs-modified QCTF was established for carbon dioxide (CO2) sensing. When the integration time is set to 331 s, the system demonstrates a normalized noise equivalent absorption (NNEA) coefficient as low as 1.33 × 10-10 cm-1·W·Hz-1/2. Featuring miniaturization and high sensitivity, the proposed system offers a novel technical route for environmental monitoring and industrial process analysis.

Bi-embedded Bi2WO6 ohmic junction photocatalysts (Bi-BWO) were synthesized via a one-step direct hydrothermal route or hydrothermal method followed by in situ reduction using different reductants. The Bi(N)-BWO prepared via an in situ reduction pathway using NaBH4 showed better physicochemical and photocatalytic redox performances than the Bi-BWO via a direct hydrothermal route using glucose or ascorbic acid as a reductant. The Bi-BWO displayed an enhanced photocatalytic redox activity in Cr(VI) reduction and tetracycline (TC)/methylene blue (MB) degradation under visible light, which was ascribed to the synergy of the ohmic junction and localized surface plasmon resonance (LSPR) of Bi nanoparticles (Bi NPs). The Bi(N)-BWO provided the highest removal efficiencies with 93.4% Cr(VI) and 77.0% TC removal rates for 120 min, whose reaction rates were 4.5- and 2.5-fold higher than those of the pristine Bi2WO6, respectively. Notably, the Bi(N)-BWO exhibited a superior simultaneous removal efficiency of Cr(VI)/TC with the reaction rates of 85.4 × 10-3 for Cr(VI) and 16.4 × 10-3 min-1 for TC, which are separately 4.0- and 1.4-fold higher than those in the single Cr(VI) and TC systems, respectively. This work provides a feasible approach to improve the photocatalytic performances of bismuth-based catalysts in wastewater remediation.

Multicolor colorimetric tannic acid detection enabled by coordination-mediated oxygen vacancies modulation in MoOx nanosheets.

Accurate and rapid identification of the microbial phenotype is pivotal for public safety and health. However, the traditional methods for microbial taxonomic discrimination are limited by their time-consuming nature and the requirement for specialized personnel. Here, we developed a biosynthetic strategy capable of identifying microorganisms at multiple taxonomic levels (i.e., kingdoms, phyla, orders, genera, and species) without biochemical assays or genetic amplification. Silver nanoparticles (AgNPs) biosynthesized by different microorganisms display distinct localized surface plasmon resonance (LSPR) spectra, zeta potential, and nanoparticle diameter. The correlation between the characteristics of AgNPs and microbial phenotypes is constructed by using machine learning algorithms. Notably, external stimuli were exploited to amplify differences among undifferentiated microorganisms, thus enabling the accurate differentiation of species-level microbes. This study not only offers a universal sensing tactic for accurate discrimination of microorganisms at different taxonomic levels but also opens an avenue for the application of biosynthetic nanomaterials in point-of-care screening of biomarkers.

Herein, a novel silver nanocrystal-patterned (Ag-NCP) metasurface-based electrochemiluminescence (ECL) sensor for the detection of miRNA-92a-3p in extracellular vesicles (EVs) was constructed with a luminescent 2,2'-bipyridine-5,5'-diamine (Bpy)-covalent organic framework (COF). On the basis of the soft-template and spatial confinement effects of micelles, the ordered nucleation and growth of Ag NCs finally yielded an Ag-NCP metasurface with synergistic structure characteristics of a long-range ordered arrangement and a short-range disordered morphology. Long-range order was defined as the uniform and periodic spatial arrangement of Ag NCs over macroscopic dimensions, which was characterized by a stable and regular structural organization. By comparison, short-range disorder refers to the irregularity in the size, surface morphology, and spacing of adjacent Ag NCs on the local nanoscale with random and variable features. The short-range disordered morphology of irregular Ag NCs in the metasurface generated high-density electromagnetic hotspots due to the localized surface plasmon resonance and the surface plasmon-coupling effect. It greatly enhanced the local electromagnetic field and triggered the Purcell effect, thereby accelerating the luminescence process and improving the ECL efficiency of the Bpy-COF. Moreover, the long-range-ordered arrangement of Ag NCs formed a dense electromagnetic network in the Ag-NCP metasurface to improve the stability and persistence of luminescent signals. The constructed Ag-NCP metasurface-based ECL sensor was successfully applied to the detection of miRNA-92a-3p with a linear range of 1 fM to 10 nM and a limit of detection of 0.36 fM. This biosensor was employed successfully for the detection of miRNA-92a-3p in ascites from gastric cancer patients, which can serve as an auxiliary diagnostic tool.

Tumor nanocatalytic therapy represents a promising transformative technology for treating malignant tumors, yet is often limited by insufficient catalytic activity and adaptive tumor microenvironment (TME) resistance. Herein, we develop a plasmonic Pt-CuO2 nanozyme that integrates plasmonic enhancement with self-sufficient H2O2 supply for augmented cascade catalytic therapy. The nanozyme comprises Pt nanoparticles (NPs) and CuO2 nanodots co-deposited on Au nanostars and encapsulated within PEGylated ZIF-8 metal-organic frameworks (MOFs). It exhibits strong near-infrared localized surface plasmon resonance, enables intrinsic H2O2 generation, and depletes glutathione, effectively disrupting intratumoral redox homeostasis. Under acidic TME conditions, the MOFs degrade, releasing Pt NPs and CuO2 nanodots to produce ∙OH via peroxidase-like and Fenton-like catalytic reactions. Plasmonic heating and "hot electron" injection under 808nm laser irradiation further promote ∙OH generation. This process induces mitochondrial dysfunction, suppresses adenosine triphosphate biosynthesis and downregulates heat shock proteins, thereby increasing thermal sensitivity of cancer cells and enhancing the efficacy of mild plasmonic hyperthermia therapy (PHT). In a triple-negative breast cancer murine model, the nanozyme demonstrates superior anticancer performance through the synergy of plasmon-enhanced catalysis, self-supplied H2O2, redox homeostasis disruption, and mild PHT. This study provides a novel strategy for efficient nanocatalytic therapy with substantial potential for clinical translation.

Exploring peroxidase substrates driven etching of gold nanorods towards indirect detection of amyloid beta1-42.

Metal-regulated MXene nanozyme with second near-infrared-triggered photothermal and chemodynamic synergy for anti-infection therapy and transcriptomic deciphering of antibacterial mechanisms.

The development of plasmonic electrochemical biosensors using the new generation of deep learning algorithms is a potent pathway toward the troublesome, immediate and field-mediable diagnostics of the pathogen. This article provides a combination of a MobileNet-Transformer and Gated Recurrent Unit (GRU) deep neural network with a nanostructured plasmonic biosensor designed to sense Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus at an early stage. To augment the charge-transfer kinetics in the biosensor, localized surface plasmon resonance (LSPR) is utilized by use of gold-nanoparticle graphene oxide hybrid nanocomposites which lead to maximized electrochemical responses. The platform has ultra-low E. coli, Salmonella, and S. aureus limits of detection of 0.12pg/mL, 0.17pg/mL and 0.21pg/mL, respectively using 5 μL of sample and a time of assay of less than 10min. The deep learning pipeline processes raw voltammetric signals automatically with MobileNet-Transformer being helpful to determine the features effectively and GRU to reduce the noise related to time. The system was better than baseline CNN and RNN models, with a classification accuracy 95.6% and area under the curve of 0.986 as well as better precision-recall profiles. The vehicular combinations of plasmonic enhancement and deep learning deposition make it possible to realize real-time on-device decision-making that can be made applicable in food safety checks, environmental or point-of-care diagnoses. This paper illustrates a scalable path to AI-assisted electrochemical biosensing and a similar performance on par with laboratory benchtop systems and that is fully compatible with low-cost diagnostic hardware in a portable format.

This study investigates the effectiveness of optoporation, activated by a titanium nitride micro-array device, in transporting a wide range of biomolecules into cells. Titanium nitride is a propitious plasmonic material exhibiting localised surface plasmon resonances within the near-infrared biological transparency window. Thin films of titanium nitride were deposited on a glass substrate via sputtering, and a periodic TiN micro-array device was fabricated (1 cm × 1 cm) through photolithography and chemical etching. When the device is irradiated with a laser at 1064 nm with a laser fluence of 10.28 mJ cm-2 and a motorised scanning speed of 5 mm s-1 in the presence of biomolecules, photothermal bubbles form near the plasma membrane and temporarily create pores that facilitate the smooth entry of biomolecules into the cells. Our TiN micro-array device with a laser-scanning setup can transfect more than a million cells within 1 minute. Utilising this device, a variety of biomolecules, including propidium iodide (PI) dye (668.4 Da), EGFP-plasmid DNA (229.4 kDa), and β-galactosidase enzyme (465 kDa), were efficiently delivered into several mammalian cell lines (L929, SiHa, and NIH/3T3), achieving high delivery efficiency and excellent cell viability. The results highlight that the maximum delivery efficiency for the PI dye is 95%, and the cell viability reaches 98% in L929 cells. Similarly, for large molecules like the β-galactosidase enzyme, the delivery efficiency is as high as 94%, with 97% cell viability. The MTT assay confirmed that the device exhibits no cytotoxicity during cell transfection. Thus, it holds potential for applications in cell therapy and diagnostics.

A photocurrent polarity switching photoelectrochemical aptasensor based on Er-MOF nanosheets and methylene blue for high-performance determination of CA15-3.

Photoelectrochemical (PEC) biosensing has emerged as a highly promising analytical technique, leveraging the synergistic interplay of light and electrochemical processes to achieve sensitive, selective, and rapid detection of various molecules. The core of these advanced PEC biosensors lies in the strategic utilization of semiconductor nanostructures, which act as photoactive materials to convert light energy into measurable electrical signals. This review provides a comprehensive overview of recent advancements in semiconductor nanostructures for PEC biosensing, categorizing them based on their dimensional characteristics (0-D, 1-D, 2-D, and 3-D). Initially, the discovery, development and various applications of photoactive single nano-semiconductors in PEC biosensing are elucidated. Subsequently, the paper delves into sophisticated strategies employed to improve the photoelectric conversion efficiency and enhance the PEC biosensing performance. These strategies include surface modification with dyes, deposition of noble-metal nanoparticles, exploiting localized surface plasmon resonance, ion-doping, and the formation of intricate heterojunctions, such as type-II, Z-scheme, and S-scheme configurations, between multiple photoactive nanomaterials. Drawing upon recent literature, specific examples are provided to illustrate how these engineered nanostructures contribute to superior PEC performance, enabling the development of highly efficient biosensing platforms for diverse applications. Finally, the review concludes by highlighting current challenges and outlining future directions for the continued evolution of this dynamic field.

Functionalized plasmonic nanoparticles have attracted significant attention in biomedical research due to their unique optical properties, high surface reactivity, and versatile surface chemistry. In this study, gold nanoparticles (AuNPs) were synthesized via the Turkevich citrate reduction method and subsequently functionalized using (3-glycidyloxypropyl) trimethoxysilane (GPTMS) to enhance their stability and surface reactivity. The synthesized and functionalized nanoparticles were comprehensively characterized using multiple analytical techniques. Morphological features and particle size distribution were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), while elemental composition was confirmed by energy-dispersive X-ray spectroscopy (EDS). The crystalline structure was analysed using X-ray diffraction (XRD), and the average crystallite size was estimated using the Scherrer equation. Fourier-transform infrared spectroscopy (FTIR) was employed to identify surface functional groups and confirm successful GPTMS functionalization. Additionally, UV–Vis spectrophotometry was used to evaluate the optical properties of the nanoparticles and to assess their localized surface plasmon resonance (LSPR) behavior. The results demonstrate that the functionalized AuNPs exhibit stable colloidal properties, controlled morphology, and modified optical responses due to surface engineering. The presence of additional absorption features in the UV region highlights the influence of GPTMS on the interfacial environment of the nanoparticles. The obtained results underscore the potential of GPTMSfunctionalized gold nanoparticles for applications in nanomedicine, including biosensing, drug delivery, and optical bioimaging.