Over the past decade, hybrid metal–halide perovskites have garnered significant interest for optoelectronic and photonic applications due to their exceptional light-emission properties—such as high photoluminescence quantum yield, optical gain, and amplified spontaneous emission—making them promising materials for LEDs, light-emitting transistors, and lasers.

Despite extensive studies, the fundamental photophysical mechanisms underlying ASE in these materials remain incompletely understood.

In this work, we conduct a detailed investigation of the temperature-dependent behavior of ASE and photoluminescence (PL) in a MAPbBr₃ thin film over the temperature range of 20–300 K, under both nanosecond-pulsed and continuous-wave (cw) excitation.

Under nanosecond excitation, ASE is observed throughout the entire temperature range, with a threshold that exhibits a marked temperature dependence. This behavior is attributed to thermally activated non-radiative processes. Discontinuities in the ASE threshold are observed at approximately 90 K and 190 K, corresponding to the orthorhombic–tetragonal and tetragonal–cubic phase transitions, respectively, leading to different activation energies and coupling rates of the non-radiative process.

Spontaneous emission, under both pulsed and cw excitation, reveals the contributions of free excitons (FE), bound excitons (BE), and trap states —only evident below 100 K — with their relative intensities depending on temperature and excitation conditions.

By comparing emission behavior across both excitation regimes and the temperature range, we find that ASE predominantly originates from BE, and among the three structural phases, the orthorhombic phase displays the most favorable ASE characteristics, with the lowest threshold and the weakest temperature dependence.

Our results shed light on the fundamental optical processes in MAPbBr₃ thin films, emphasizing the key role of the crystalline phase in ASE performance and the contribution of trap-related emissions to PL. These insights are crucial for guiding further improvements in the emission properties of hybrid lead halide perovskites, which are used in advanced photonic and optoelectronic applications.

Nanostructured materials, such as silver nanorod (AgNR) arrays fabricated via oblique angle deposition, offer enhanced electromagnetic fields for surface-enhanced Raman spectroscopy (SERS), enabling sensitive molecular detection. However, many bacterial biomarkers exhibit inherently low surface affinity to silver, resulting in weak or variable spectral signatures, posing a critical limitation in SERS-based biosensing. In this study, we explore how machine learning can be harnessed to extract meaningful signals from these complex and sometimes weak interactions.

We investigated six bacterial biomarkers2,3-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, pyocyanin, lipoteichoic acid (LTA), enterobactin, and β-carotene by depositing them on AgNR substrates across varying concentration levels. The SERS spectra were collected under consistent conditions without the use of affinity-enhancing surface modifications, to isolate the substrate–analyte interaction dynamics. We applied convolutional neural networks (CNNs) to both classify and quantify these biomarkers from raw spectral data.

Despite the low affinity of some molecules particularly Enterobactin and β-carotene for bare Ag surfaces, CNNs achieved over 99.9% classification accuracy across all six biomarkers. Regression models yielded R² values > 0.97 and MAEs < 0.27, outperforming support vector regression in all cases. These results highlight CNNs’ capacity to learn subtle spectral patterns that may be lost using traditional feature-based methods, especially when surface interactions are weak or inconsistent.

This work demonstrates that deep learning models can effectively overcome material-level limitations in SERS sensing caused by low analyte-substrate affinity. By combining nanostructured AgNR arrays with AI - driven analysis, we offer a robust strategy for reliable biomarker detection even under suboptimal surface binding conditions, supporting the development of smarter nanomaterial-based biosensors for clinical and environmental applications.

Perovskite nanocrystals (NCs) of a fully inorganic composition have emerged as effective materials for optoelectronic applications over the past decade. Their photoluminescence and stability are significantly influenced by the surface chemistry, particularly the surfactant molecules used for defect passivation. While several experiments have investigated the ligand dependence of the spontaneous emission properties, the ligand's role in the optical gain and stimulated emission for perovskite NCs has almost entirely been unexplored.

In this work, we aim to fill this gap, investigating how the capping ligand of CsPbBr3 perovskite NC thin films affects their amplified spontaneous emission (ASE) characteristics, their photostability, and their sensitivity to ambient air.

We analyzed four distinct samples with different capping ligands, namely oleic acid/oleylamine, didodecyldimethylammonium bromide, 3-(N,N-dimethyloctadecylammonio)-propanesulfonate, and lecithin. We discuss the impact of these four ligands on the NCs' quantum efficiency, optical gain, optical stability, and atmospheric sensing properties, investigating the underlying chemical–physical mechanisms responsible for the observed variations. In particular, we show that all of the samples show ASEs under nanosecond pumping, but with very different thresholds, and that the dependence of the ASE's intensity on the sample environment is also strongly ligand-dependent.
Finally, we performed a comparison between these four ligands, demonstrating that lecithin capping allows the optimal performance to be obtained concerning the ASE threshold and sensing capabilities.

Hydroxypropyl cellulose (HPC) nanogels with thermoresponsive properties were synthesized through a novel polymerization pathway. This study determined the optimal concentrations of surfactant and reaction temperature by evaluating the solution dispersity across various HPC molecular weights. An inverse relationship was observed between the molecular weight of HPC and the required concentration of the surfactant dodecyltrimethylammonium bromide (DTAB); polymers with higher molecular weights needed less surfactant. Nanogels were formed at double the lower critical solution temperature (LCST) of the polymer, with divinyl sulfone (DVS) employed as a crosslinking agent to establish the polymer network. This novel synthesis method ultimately resulted in nanogels with a low polydispersity index. Dynamic light scattering (DLS) was used to assess the influence of crosslinker concentration on thermoresponsive behavior, revealing a consistent decrease in average size as the crosslinker molarity increased. Additionally, small-angle neutron scattering (SANS) was utilized to investigate how the internal structural changed with the temperature, highlighting marked deviations from the typical fuzzy sphere morphology. This study of the morphology of HPC nanogels as a function of temperature and molecular weight allows us to better understand the distribution of the polymeric network, investigate the phase transition, and determine the effect of molecular weight on the final size of the nanogels.

Abstract:
The detection of biomolecules such as nutrients, disease biomarkers, drugs, and toxins in human biofluids is essential for advancing healthcare and diagnostics. Traditional centralized laboratory assays, like enzyme-linked immunosorbent assays (ELISA), are limited by sample preparation complexity and processing time. To address these challenges, we initially focused on enhancing ELISA sensitivity by incorporating single-atom nanozymes (SANs) as robust catalytic amplifiers. SANs exhibit exceptional stability across a wide pH and temperature range and display superior catalytic activity toward hydrogen peroxide, effectively substituting natural peroxidases.

We developed methods to integrate SANs into ELISA workflows and expanded their application to electrochemical platforms and lateral-flow immunoassays, enabling rapid and sensitive detection of target analytes in various biological matrices. The SAN-based biosensors demonstrated reproducible performance and significant improvements in sensitivity and stability compared to traditional enzyme-based assays.

To further address the growing demand for continuous, on-body health monitoring, we integrated these SAN-based sensing platforms with flexible, wearable energy management modules, creating a self-powered wearable microgrid system. This system ensures continuous and autonomous operation by harvesting biomechanical and environmental energy from the wearer. Additionally, the lightweight and flexible design of the wearable microgrid system provides enhanced comfort and long-term wearability, enabling real-time, high-frequency monitoring of biomarkers directly on the body.

Conclusions:
The SAN-enabled ELSIA demonstrated ten times greater sensitivity compared to a commercial product in detecting one type of Alzheimer's disease. By transitioning from traditional ELISA to SAN-enabled biosensing and integrating with self-powered, flexible wearable systems, our research paves the way for continuous, autonomous biomolecular monitoring, including glucose, lactate, Vitamin C, and levodopa from sweat. This comprehensive approach meets the demands for real-time, user-friendly healthcare monitoring and advanced human–machine interfacing.

Introduction:
Anthocyanins (AntCys) are natural pigments with pH-sensitive chromatic properties and antioxidant activity, making them attractive for stimuli-responsive materials. However, their application is limited by poor stability in neutral and alkaline environments. This study explores the encapsulation of AntCys, extracted from red cabbage, into surface-nanostructured microparticles obtained via Pickering emulsion polymerization to enhance stability and enable environmental responsiveness.

Methods:
The AntCy extract was incorporated into poly(methacrylic acid) microparticles synthesized using a Pickering emulsion stabilized by silica nanoparticles. Encapsulation efficiency was quantified spectrophotometrically. The release behavior of AntCy was studied in water, saline solution, and ethanol–water mixtures, and interpreted using various kinetic models. Morphology and uptake were evaluated by SEM and colorimetric analysis. Color responses to pH and gas vapors were tested for sensing applications.

Results:
The encapsulated AntCys in the microparticles were predominantly stabilized as flavylium cations inside the acidic polymer matrix. This way, the microparticles could preserve the integrity of AntCys towards degradation in high pH solutions yet maintaining its antioxidant ability. The release of AntCys was highly sensitive to external conditions. In saline and ethanol-rich environments, the release kinetics followed a diffusion-based profile, with increased release rates attributed to ionic screening and enhanced solubility. The colorimetric response of AntCy-loaded microparticles enabled the visual detection of acidic and basic vapors. A biocompatible polyvinyl alcohol composite embedded with microparticles was successfully prototyped for gas sensing.

Conclusions:
Pickering emulsion-derived polymeric microparticles provide a robust platform for encapsulation and stabilization of anthocyanins, enabling controlled release and preserving antioxidant activity. Their pH- and solvent-responsive release profiles, combined with visible colorimetric changes, make them suitable for use in intelligent packaging, biosensors, and environmentally responsive coatings.

Electrochemical overall water splitting (OWS) is a critical technology for the sustainable generation of high-purity hydrogen and oxygen using only water and renewable electricity. The development of Earth-abundant, bifunctional electrocatalysts capable of efficiently driving both the HER and the OER within a single system is imperative for the advancement of alkaline water electrolyzer technologies.

In this study, cobalt phosphide (CoP) and cobalt–iron phosphide (CoFeP) were successfully prepared on a copper substrate via an electroless deposition method using sodium hypophosphite (NaH₂PO₂) as the phosphorus source and the reducing agent. The anchoring of platinum (Pt) nanoparticles onto electrolessly deposited materials was achieved through the galvanic displacement technique. The morphology, composition, and crystallographic structure of the catalysts were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The bifunctional electrocatalytic performance of the materials for OWS was demonstrated in a two-electrode configuration using a 1 M KOH electrolyte.

Among the catalysts, Pt–CoFeP demonstrated superior bifunctional activity with a low cell voltage of 1.58 V at 10 mA cm^-2 for overall water splitting, surpassing the performance of Pt–CoP due to the synergistic interactions between Co, Fe, and Pt. The incorporation of Fe into the system resulted in enhanced electrical conductivity and modulation of the electronic structure. Platinum decoration led to significant improvements in catalytic kinetics, a reduction in overpotentials, and the facilitation of efficient charge transfer at both electrodes. This work presents a scalable strategy for engineering platinum-modified transition metal phosphides as robust, high-performance bifunctional electrocatalysts for alkaline water electrolysis.

Acknowledgments

This research was funded by a grant (No. P-MIP-23-467) from the Research Council of Lithuania.

Introduction:
Soft, mechanically compliant materials capable of converting mechanical energy into electrical output are essential for the next generation of wearable electronics and self-powered sensors. While piezoelectricity is typically associated with crystalline ceramics or ferroelectric polymers, recent efforts have focused on organic mixed ionic–electronic conductors (OMIECs) as functional alternatives. Here, we report a moldable, water-processable PVA/PANi composite exhibiting strain-sensitive electrical response and piezoelectric-like energy conversion, synthesized through a straightforward frozen-gel polymerization method.

Methods:
Poly(vinyl alcohol) and glycerol were dissolved in water to form a hydrogel precursor, followed by in situ polymerization of aniline under frozen conditions. The composite was subjected to mechanical compression and stretching cycles, and its electrical output was evaluated via open-circuit voltage (VOC), short-circuit current (ISC), and power output across various load resistances. The structure was characterized via scanning electron microscopy (SEM), revealing platelet-like nanoparticle PANi domains embedded in the soft matrix.

Results:
The composite exhibited a reproducible piezoelectric-like response under compressive strain, with VOC reaching 0.08 mV/mm and ISC exceeding 8 µA/mm² at ~4.6% strain. Maximum power density of ~7 nW/cm³ was obtained at an optimal load of 1 kΩ. Theoretical Pmax estimates based on VOC × ISC closely matched experimental results. SEM revealed granular and fibrillar self-assembled nanoparticle PANi domains, likely templated by ice grains during polymerization, suggesting an interface-driven morphological control.

Conclusions:
The PVA/PANi composite exhibits mechano-electrical conversion in the absence of conventional piezoelectric phases, enabled by a unique morphology arising from frozen-gel polymerization. Its moldability, conductivity, and scalability highlight its potential for low-cost, flexible energy harvesting and sensing applications.

Conventional biosensors frequently rely on biological enzymes such as glucose oxidase and peroxidase to catalyse specific biochemical reactions. While effective, these enzymes present several critical limitations, including limited operational stability, high production and storage costs, and sensitivity to environmental conditions. These drawbacks significantly hinder their practical application in long-term diagnostics, portable sensing devices, and resource-limited settings.

This project proposes the development of enzyme-free biosensors using silver nanoparticles (AgNPs) as catalytic substitutes. AgNPs exhibit unique and advantageous physicochemical properties, including a large surface area, excellent electrical conductivity, and intrinsic peroxidase-like activity. These features make them ideal nanozyme candidates for next-generation biosensors that are both efficient and stable under diverse conditions.

This study involves the synthesis and characterisation of AgNPs via chemical and environmentally friendly (green) methods, followed by their integration into both electrochemical and colorimetric biosensing platforms. The biosensors are tested for their ability to detect clinically and industrially relevant biomolecules, particularly glucose and hydrogen peroxide.

Key performance metrics such as the biosensors' sensitivity, detection limit, response time, selectivity, and long-term operational stability are systematically evaluated and compared with those of their conventional enzyme-based counterparts. The ultimate goal is to develop a cost-effective, reusable, and robust biosensor suitable for applications in medical diagnostics, food safety analysis, and environmental monitoring.

This work contributes to the growing field of nanozyme technology by offering an innovative, enzyme-free solution to overcome the limitations of traditional biosensors, paving the way for the development of more durable and accessible sensing platforms.

Upconversion nanoparticles (UCNPs) are materials that convert near-infrared photons into visible and/or UV emissions. This phenomenon generates high-energy radiation from the absorption of low-energy photons. The synthesis of UCNPs requires a support matrix composed of oxides (Y₂O₃) or fluorides (NaYF₄), which are essential for their optical properties. These materiales have a wide range of applications in bioimaging, drug delivery and energy storage in solar devices.

For this, UCNPs were synthesized by coprecipitation method. For better control of particle size and to obtain a beta (β) crystalline phase, the particles were subjected to heat treatment at 400 °C for 17 h inside a muffle. Subsequently, nanoparticles were deposited on a tetraethyl orthosilicate (TEOS) film synthesized by sol–gel technique, in a molar ratio of TEOS/H₂O/Ethanol at pH of 2, 3 and 5 in a temperature range of 25 to 80 ºC.

Both materials were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), rheology, confocal (CM) and scanning electron microscopy (SEM). Through FT-IR, the characteristic bands of functional groups corresponding to TEOS were confirmed. The CM results exhibit that UCNPs emit shorter wavelengths and, therefore, higher energy radiation. SEM images show the synthesized films have an irregular and porous surface. However, this behavior increases as the pH decreases and the temperature rises. From the viscoelastic analysis, the films show a stable structure within linear viscoelastic region. Also, their possible transition temperatures from a gel state to a glassy state are observed at 80 ºC.

In conclusion, the particles show upconversion properties and their morphology and size depend on heating time during synthesis. On the other hand, roughness, porosity and structural arrangement of films changes when the pH and temperature of system varied. The viscoelastic properties show stable structures. Finally, the material properties indicate their possible use in solar concentrators for plastic degradation.