This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu3+-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu3+ ions using Reisfeld's approximation. Eu3+-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu3+ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu3+ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu3+), confirming the successful doping of Eu3+ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu3+ incorporation, indicating strong coupling between Eu3+ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the 5D0 → 7F2 transition of Eu3+ ions under UV excitation. Using Judd-Ofelt (JO) analysis, the intensity parameters (Ω 2, Ω 4, Ω 6) were derived, providing insights into the asymmetry of the Eu3+ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu3+ dopants were examined, showing efficient sensitization of Eu3+ through excitation of the ZnO host, with an optimal Eu3+ doping level maximizing luminescence. Eu3+-doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging.

Triclosan (TCS) is used as an antibacterial agent in various products. One of the major issues associated with TCS is its limited solubility in aqueous media, which can reduce its effectiveness against bacteria. In this study, we enhanced the aqueous solubility and antibacterial activity of TCS by using a re-dispersible emulsion powder stabilized with gold nanoparticles (GNPs). The developed formulation (TCS/PEG-B/GNPs) demonstrated the ability to dissolve in aqueous media and provided good stability. An antibacterial investigation was conducted using drug-resistant bacterial strains, Escherichia coli (E. coli) BAA-1161 and methicillin-resistant Staphylococcus aureus (MRSA), as model bacteria. The results showed that TCS/PEG-B/GNPs had the highest antibacterial activity. The MRSA strain demonstrated greater susceptibility to TCS (both TCS alone and TCS in the formulation) than E. coli BAA-1161. The cytotoxicity assay was also conducted in THP-1 cells and it was found that the viability of THP-1 cells treated with a 5× dilution of TCS/PEG-B/GNPs was higher than 80%. Altogether, our study proposes a novel approach to overcome the solubility concerns of TCS. These results demonstrated an increase in TCS's solubility and efficacy, which holds great promise for future applications.

Doping in pure materials causes vital alterations in opto-electrical and physicochemical characteristics, which enable the produced doped material to be highly efficient and effective. The current work focused on the synthesis of C/N-co-doped-ZnO nanorods via a facile, eco-friendly, and solvent-free mechano-thermal approach. The synthesized C/N-co-doped ZnO nanorods were employed for the photocatalytic decay of methylene blue (MB) and brilliant cresyl blue (BCB) dyes, and their degradation capability was compared with that of pure ZnO nanoparticles prepared via a precipitation approach. The FESEM findings confirmed the formation of rod-shaped nanostructures of co-doped ZnO nanoparticles, and EDX and XPS results revealed the successful doping of C and N atoms in ZnO lattices. The XRD and XPS results substantiated that N-doping in the ZnO lattice followed substitutional and interstitial mechanisms, while C-doping followed a substitutional pathway. The co-doped ZnO nanorods exhibited highly enhanced degradation potential toward both MB (∼99%) and BCB (∼98%) dyes upon exposure to visible light for 60 min in a basic medium at pH = 10 owing to factors such as formation of new energy states within the band gap of ZnO, delayed recombination of photogenerated charge carriers, and formation of lattice defects in the ZnO lattice due to C and N doping. The MB and BCB dyes photodegraded at degradation rates of 637.23 × 10-4 and 775.25 × 10-4 min-1, respectively, and the photodegradation process showed good agreement with the pseudo-first-order kinetics in the presence of co-doped ZnO nanorods under visible light illumination. The ˙O2 - radicals were the key reactive species involved in the decay of MB and BCB dyes over co-doped ZnO, as confirmed via scavenger studies, and the C/N-co-doped ZnO nanorods retained approximately 90% and 91% efficiencies for BCB and MB dyes, respectively, after three successive cycles of reuse, which confirmed their good stability and reusability under visible light.

Radiation therapy is a common cancer treatment but often damages surrounding healthy tissues, leading to unwanted side effects. Despite technological advancements aimed at improving targeting, minimizing exposure to normal cells remains a major challenge. High-Z nanoparticles, such as gold nanoparticles (AuNPs), are being explored as nano-radiosensitizers to enhance cancer treatment through physical, biological, and chemical mechanisms. This study focuses on evaluating the chemical and biological radiosensitizing effects of AuNPs exposed to ionizing radiation (0-50 Gy), specifically their production of reactive oxygen species (ROS) and their impact on cancer cells. ROS generated by AuNPs of varying sizes and coatings were quantified using fluorescence probes for hydroxyl radicals (HO·) and singlet oxygen (1O2). The radiosensitizing effects on MDA-MB-231 cancer cells were assessed via clonogenic assays. Our results show a clear dependence of ROS production on AuNP size. Interestingly, PEG-capped AuNPs did not significantly enhance HO· production but greatly increased 1O2 production, suggesting that multiple reactive species contribute to the radiosensitization process. Clonogenic assays confirmed that PEG-capped AuNPs produced stronger radiosensitizing effects than citrate-capped AuNPs, with smaller AuNPs providing more pronounced biological effects. This study underscores the importance of conducting both chemical and biological evaluations to fully understand the radiosensitization efficacy of AuNPs.

Interference of surface plasmons has been widely utilized in optical metrology for applications such as high-precision sensing. In this paper, we introduce a surface plasmon interferometer with the potential to be arranged in arrays for parallel multiplexing applications. The interferometer features two grating couplers that excite surface plasmon polariton (SPP) waves traveling along a gold-air interface before converging at a gold nanoslit where they interfere. A key innovation lies in the ability to tune the interference pattern by altering the geometrical properties of the gold nanoslit such that one, two or more resonance modes are supported in the nanoslit. Our experimental results validate the approach of our design and modelling process, demonstrating the potential to fine-tune geometrical parameters such as grating coupler pitch, depth, duty cycle, and nanoslit dimensions to alter the transmitted radiation pattern and the transmittance. We demonstrate the ability of a grating coupler to induce focusing of SPP waves to an arbitrary location on chip by illuminating with a converging Gaussian beam. Additionally, we observed far-field interference patterns linked to the multimodal operation of the nanoslit.

The diffusion motions of individual polymer aggregates in disordered porous media were visualized using the single-particle tracking (SPT) method because the motions inside porous media play important roles in various fields of science and engineering. In the aggregates diffused on the surfaces of pores, continuous adsorption and desorption processes were observed. The relationship between the size of the aggregates and pore size was analysed based on diffusion coefficients, moment scaling spectrum (MSS) slope analysis, and diffusion anisotropy analysis. The obtained diffusion coefficients were different for different aggregates and pore sizes. The MSS slope analysis indicated that more than 85% of the aggregates showed confined diffusion for all the conditions investigated. The diffusion anisotropy analysis suggested that the diffusion of the aggregates exhibited anisotropic behaviour. The interactions between the aggregates and the pores were complex, causing the aggregates to exhibit motions distinct from those associated with surface diffusion on smooth surfaces.

Hydrothermal carbonization (HTC) of carbohydrates has been reported as a sustainable and green technique to produce carbonaceous micro- and nano-materials. These materials have been developed for several applications, including catalysis, separation science, metal ion adsorption and nanomedicine. Carbon nanoparticles (CNPs) obtained through HTC are particularly interesting for the latter application since they exhibit photothermal properties when irradiated with near-infrared (NIR) light, act as an antioxidant by scavenging reactive oxygen species (ROS), and present good colloidal stability and biocompatibility. However, due to the highly disordered structure, there is still a poor understanding of the mechanism of synthesis of CNPs. Consequently, the modulation of the CNP properties by controlling the synthetic parameters is still a challenge. In this work, a novel and simplified HTC synthetic strategy to obtain non-aggregated glucose derived CNPs in the 15-150 nm size range with precise control of the diameter is presented, together with an advance in the understanding of the reaction mechanism behind the synthesis. Modifications of the synthetic parameters and a post-synthesis hydrothermal process were applied to increase the bulk order of CNPs, resulting in an increase of the photothermal and ROS scavenging activities, without affecting the morphological and colloidal properties of the nanomaterial.

We have employed a triazine-based conjugated polymer network (CPN) for the selective detection of hypochlorite in a semi-aqueous environment. CPNs have been widely employed in gas capture, separation, and adsorption, but the fluorescent properties of CPNs possessing extensive π-conjugated systems tend to be unexplored. Herein, we report the photophysical properties of the CPN and investigate its sensing capability towards hypochlorite. Spectroscopic investigations reveal that the CPN forms π-stacked aggregates in aqueous medium, while loose aggregates were observed to be formed in hydrophobic solvents. The fluorogenic CPN demonstrates remarkable selectivity via fluorescence quenching and a blueshift response towards hypochlorite in a semi-aqueous medium, accompanied by a color change under UV light. Such a turn-off fluorescence response, along with the blue shift upon hypochlorite sensing, was attributed to the oxidation of the sulfur atom of the thiophene functionality of the CPN, consequently resulting in suppression of Intramolecular Charge Transfer (ICT) in the corresponding oxidized adduct. The fluorescence intensity of the CPN exhibits a linear response to hypochlorite concentration, achieving a low detection limit of 1.2 nM. Furthermore, the practical applicability was demonstrated by the detection of hypochlorite in water samples and fluorescent test-paper strips. Additionally, the present system is utilized for bio-imaging of endogenous hypochlorite in RAW 264.7 cells.

Nanocrystals are widely explored for a range of medical, imaging, sensing, and energy conversion applications. CdS nanocrystals have been reported as excellent photocatalysts, with thin film CdS also highly important in photovoltaic devices. To optimise properties of nanocrystals, control over phase, facet, and morphology are vital. Here, CdS nanocrystals were synthesised by the solvothermal decomposition of a Cd xanthate single source precursor. To attempt to control CdS nanocrystal surfaces and morphology, the solvent used in the nanocrystal synthesis was altered from pure trioctylphosphine oxide (TOPO) to a mixed TOPO : fluorinated aromatic amine (3-fluorobenzyl amine (3-FlBzAm) or 3-fluoroaniline (3-FlAn)), where 19F provides a sensitive NMR-active surface probe. Powder X-ray diffraction found that the CdS nanocrystals synthesised from TOPO : 3-FlAn solvent mixtures were predominantly cubic whilst the TOPO : 3-FlBzAm synthesised nanocrystals were predominantly hexagonal. Raman spectroscopy identified hexagonal CdS in all samples. Solid-state NMR of 113Cd, 19F, 13C, and 1H was employed to investigate the local Cd environments, surface ligands, and ligand interactions. This showed there was a mixture of CdS phases present in all samples and that surfaces were capped with TOPO : fluorinated aromatic amine mixtures, but also that there was a stronger binding affinity of 3-FlBzAm compared with 3-FlAn on the CdS surface, which likely impacts growth mechanisms. This work highlights that fluorinated aromatic amines can be used to probe NC surfaces and also control NC properties through their influence during NC growth.

In this study, we used two-dimensional electronic spectroscopy to examine the early femtosecond dynamics of suspensions of colloidal gold nanorods with different aspect ratios. In all samples, the signal distribution in the 2D maps at this timescale shows a distinctive dispersive behavior, which can be explained by the interference between the exciting field and the field produced on the nanoparticle's surface by the collective motion of electrons when the plasmon is excited. Studying this interference effect, which is active only until the plasmon has been dephased, allows for a direct estimation of the dephasing time of the plasmon of an ensemble of colloidal particles. Our findings provide insight into the fundamental behavior of plasmonic states and highlight the potential of two-dimensional electronic spectroscopy in uncovering ultrafast and coherent optical phenomena at the nanoscale.