UV Light Absorption Research Articles

Modification on Fiber from Alkali Treatment and AESO Coating to Enhance UV-Light and Water Absorption Resistance in Kapok Fiber Reinforced Polyester Composites

ABSTRACT Environmental contamination poses a significant threat to the integrity of materials, including metals and composites. Addressing the degradation of natural fiber-reinforced polymer composites necessitates effective management strategies, particularly in mitigating UV and water-induced deterioration. This study explores the efficacy of Acrylated Epoxidized Soybean Oil (AESO) coating treatment following alkali treatment as a potential solution. Alkali treatment of Kapok fiber (KF) combined with polymer coating yielded composites exhibiting superior mechanical properties, particularly in tensile and flexural strength, following a 30-day aging period. Remarkably, the application of alkali and coating treatments led to a substantial enhancement in the mechanical strength of polyester composites, with the highest tensile strength recorded at 96.04 MPa. This represented a notable increase of 31.97% compared to untreated KF specimens. The observed enhancement in composite performance underscores the critical role of interfacial adhesion between fibers and the matrix, particularly under conditions of UV exposure and water immersion. Importantly, the study demonstrates that alkali treatment and polymer coating effectively mitigate degradation in Natural Fiber-Reinforced Polymer Composites, thereby offering promising avenues for enhancing their durability and longevity.

Novel nanoparticle composed by Ovalbumin-OSA modified pectin-rutin for improving the stability of Monascus pigments

To improve the resistance of Monascus pigments (MPs) to adverse environmental factors, a nanoparticle carrier was constructed using ovalbumin, rutin and pectin modified by octenyl succinic anhydride. According to the determination of particle size, ζ-potential and microstructure, the composite nanoparticles exhibited the "core-shell" structure. Specifically, the ovalbumin core was encapsulated by the modified pectin adsorbed with rutin. Spectroscopic analysis demonstrated that electrostatic interactions, hydrogen bonding and hydrophobic interactions between wall materials and MPs were the main driving forces to form composite nanoparticles. The stabilities of light, thermal and storage of MPs were significantly enhanced after encapsulation due to the physical barrier effect of the wall materials against external disturbances and the multiple functions of rutin, including free radical scavenging, absorption of partial UV and scatter light, and possible co-pigmentation effects with MPs. Moreover, the composite nanoparticles exhibited higher inhibition activity against pancreatic lipase and antioxidant activity compared with those of free MPs. The results provided an ideal way to develop new MPs products, which had long-lasting and stable performance during food processing and storage.

Substituent effects in 2-hydroxybenzophenone-based ultraviolet absorbers

2-Hydroxybenzophenone is the simplest molecule among benzophenone-based UV absorbers. Changing the position and type of substituents affects the strength of intramolecular hydrogen bonding and thus modulates the UV absorption properties. In this work, 132 2-hydroxybenzophenone-based UV absorbers with different substituent positions and species were designed to investigate the substituent effect in their UV absorption properties. The results show that when the substituent positions are the same, the characteristic peaks of the compounds containing substituents of the same group of atoms or homologous groups correspond to similar wavelengths. When the substituent groups are the same, the wavelength redshift of the characteristic peaks of the UV absorption spectra of the compounds of the NX and NZ classes is more pronounced than that of the remaining species, and the substituent group containing N atoms causes the molecule to have a more pronounced wavelength redshift. The redshift of the characteristic absorption peaks corresponding to the wavelengths decreases with the increase of the energy level difference. Atoms-in-molecules (AIM) analysis showed that the electron-absorbing group in the compound enhances the hydrogen bond strength to a lesser extent than the electron-donating group. Natural Bond Orbital (NBO) analysis further revealed that the type and position of the substituent groups in the molecular structure influenced the strength of the intramolecular hydrogen bonding by affecting the distribution of the charges among individual atoms in the 2-hydroxybenzophenone molecules. This work aims to reveal the effect of substituents on the UV absorption properties of 2-hydroxybenzophenone-based molecules and to provide theoretical guidance for the design of such UV absorber molecules absorbing UV light at specific wavelengths.

Femtosecond to Microsecond Observation of Photochemical Pathways in Nitroaromatic Phototriggers Using Transient Absorption Spectroscopy.

The synthetic accessibility and tolerance to structural modification of phototriggered compounds (PTs) based on the ortho- nitrobenzene (ONB) protecting group have encouraged a myriad of applications including optimization of biological activity, and supramolecular polymerization. Here, a combination of ultrafast transient absorption spectroscopy techniques is used to study the multistep photochemistry of two nitroaromatic phototriggers based on the ONB chromophore, O-(4,5-dimethoxy-2-nitrobenzyl)-l-serine (DMNB-Ser) and O-[(2-nitrophenyl)methyl]-l-tyrosine hydrochloride (NB-Tyr), in DMSO solutions on femtosecond to microsecond time scales following the absorption of UV light. From a common nitro-S1 excited state, the PTs can either undergo excited state intramolecular hydrogen transfer (ESIHT) to an aci-S1 isomer within the singlet state manifold, leading to direct S1 → S0 internal conversion through a conical intersection, or competitive intersystem crossing (ISC) to access the triplet state manifold on time scales of (1.93 ± 0.03) ps and (13.9 ± 1.2) ps for DMNB-Ser and NB-Tyr, respectively. Deprotonation of aci-T1 species to yield triplet anions is proposed to occur in both PTs, with an illustrative time constant of (9.4 ± 0.7) ns for DMNB-Ser. More than 75% of the photoexcited molecules return to their electronic ground states within 8 μs, either by direct S1 → S0 relaxation or anion reprotonation. Hence, upper limits to the quantum yields of photoproduct formation are estimated to be in the range of 13-25%. Mixed DMSO/H2O solvents show the influence of the environment on the observed photochemistry, for example, revealing two nitro-S1 lifetimes for DMNB-Ser in a 10:1 DMSO/H2O mixture of 1.95 ps and (10.1 ± 1.2) ps, which are attributed to different microsolvation environments.

UV light absorption at 370 nm by mineral dust, organic carbon, and elemental carbon in the Himalayas and Tibetan Plateau

The mass and light absorption contributions of organic carbon (OC), elemental carbon (EC), and mineral dust influence glacial melting and potentially contribute to climate change over the high Himalayas and Tibetan Plateau (HTP). Plateau-scale investigations of these components and their respective light absorption are limited due to the high altitude. In this study, we combined the analysis of major light-absorbing substances and their corresponding multiwavelength absorption to determine their specific contributions firstly. We investigated the spatial variations of total suspended particle (TSP) mass across the HTP, noting high contributions from dust, carbonaceous components, and secondary inorganic aerosols (SNA, including sulfate, nitrate, and ammonium). Enhanced levels of primary and secondary OC and SNA were observed in the marginal areas of the HTP, associated with high relative humidity (RH) and OX levels (O3+NO2). EC was the primary contributor to light absorption, accounting for approximately 68%, 46%, and 64% in Ngari, Qinghai Lake, and Beiluhe, respectively. We found higher light-absorbing contributions from carbonaceous aerosols in the marginal areas compared to the central HTP site, particularly during the heating seasons (∼90%). Fugitive dust significantly contributed to TSP mass but not to light absorption. The concurrent constraints on the mass and optical properties of OC, EC, and dust in this study can help reduce uncertainties in climate models specific to the HTP.

Synthesis of a new Schiff base acceptor–donor molecule as a UV stabilizer for enhanced poly(lactic acid) (PLA) photoprotection

AbstractPoly(lactic acid) (PLA) is a biodegradable aliphatic polyester of significant interest. Owing to its traits, PLA stands out as one of the most widely used polymers in various fields. Nevertheless, environmental conditions, such as heat, UV light, and humidity have negative impacts on the polymer's performance as a result of the accelerating aging process. In this study, we present a novel acceptor–donor (AD) Schiff base molecule that demonstrates significant UV stabilization when incorporated into the polymer's matrix. The stabilization effect of the AD molecule was studied by using the weight loss method and tracking the functional group indices of CO (ICO) and OH (IOH) that emerge because of polymer degradation after irradiation with UV light for 300 h. The films' structures were studied by scanning electronic microscopy (SEM), atomic force microscope (AFM), and energy‐dispersive x‐ray spectroscopy (EDX) to evaluate the stabilization enhancement of AD moiety. The results exhibit a significant decrease in weight loss for blended PLA, in contrast to blank PLA. The weight loss percentage reduced from 2.5 for blank PLA to less than 0.7 for blended PLA. Furthermore, ICO and IOH indices witness a remarkable reduction which verifies the improved photodegradation resulting from AD moiety. The suggested method involves the efficient absorption of UV radiation produced during photo‐degradation by the AD molecule, which then emits this light as visible blue light without causing any damage to PLA film's chemical structure. Our results demonstrate the adaptability of AD molecules as PLA photo‐stabilizers and point to their wider significance for sustainable material applications. This work advances the stability of PLA films and provides opportunities for the creation of novel stabilization techniques based on organic electrical principles. Future studies may examine the multipurpose uses of the AD molecule in sensor materials and other contexts.Highlights Presenting a novel acceptor–donor Schiff base as a phot stabilizer of PLA. Using the weight loss method and tracking the functional group indices to test the degradation. A significant decrease in weight loss for blended PLA, in contrast to blank PLA. The Schiff base absorbing UV light, excited electrons from ground state to excited state. They return to the ground state and produce bright blue light. These movement of electrons cause no damage to the PLA polymer chains.

Multi-functionalization and recycling of basalt fibre/polypropylene laminated composites based on mixed plain-woven fabric and related interfacial decorations

The development of laminated composites of thermoplastic polypropylene (PP)/continuous basalt fabric is limited by poor mutual infiltration and weak interfacial interactions between the matrix and fabric, as well as the intrinsic flammability and susceptibility of the PP matrix to ultraviolet (UV) aging. To solve the above shortcomings in a high-efficiency manner, a multi-functional transition layer was constructed between the PP matrix and long basalt fibres (LBFs) based on a hybrid plain-woven fabric composed of LBFs weft yarns and PP warp yarns. After hot-laminating these hybrid plain-woven prepregs, the mechanical performance of the resultant laminates was optimised and strengthened by selecting the compositions of the multi-functional transition layers (comprising flexible alkyl glycidyl ether chains, various rigid inorganic nanoparticles, or a flexible-rigid hybrid layer). Among these different transition layers, the interface between the LBFs-g-MWCNTs-OH and the PP matrix presented better mutual infiltration due to the lower interfacial energy, stronger mechanical engagement effect derived from the rougher fibre surface, and higher interfacial modulus. Therefore, the fewer structural defects and more effective transfer of the applied load at the interface caused the tensile strength/modulus and flexural strength/modulus of the related hybrid weaving laminates (HWLs) to reach 278.1 MPa/31.8 GPa and 264.2 MPa/12.4 GPa, respectively. The rigid interfaces formed by the deposited nanoparticles also accelerated heat transfer from the matrix to the fibre and the absorption of UV-light inside composite, then improving the flame-retardancy and anti-UV aging performances of the corresponding HWLs. Finally, recyclability evaluations indicated that the waste LBFs-g-SiO2/PP HWLs can be used as anti-UV aging and flame-retardant agents to fabricate new modified PP pellets with multiple functions.

Density Function Theory Study on the Energy and Circular Dichroism Spectrum for Methylene-Linked Triazole Diads Depending on the Substitution Position and Conformation.

Since the discovery of metal-catalyzed azide-alkyne cycloadditions, 1,2,3-triazoles have been widely used as linkers for various residues. 1,2,3-Triazole is an aromatic five-membered cyclic compound consisting of three nitrogen and two carbon atoms with large dipoles that absorb UV light. In the past decade, we have been working on the synthesis of dense triazole polymers possessing many 1,2,3-triazole residues linked through a carbon atom in their backbone as a new type of functional polymer. Recently, we reported that stereoregular dense triazole uniform oligomers exhibit a circular dichroism signal based on the chiral arrangement of two neighboring 1,2,3-triazole residues. In this study, to investigate the chiral conformation of two neighboring 1,2,3-triazole residues in stereoregular dense triazole uniform oligomers, density functional theory (DFT) calculations were performed using 1,2,3-triazole diads with different substitution positions and conformations as model compounds and compared with our previous results.

Brightening microalgal potential: A study on organic fluorescent dyes to increase photosynthetic active radiation

Microalgae hold promise for sustainable biomass and bioactive metabolite production, yet their commercial viability faces challenges due to low productivity, often linked to inefficient light utilisation. Algae absorb light primarily in the 400–500 nm (blue) and 600–700 nm (red) range termed photosynthetically active radiation (PAR), leaving excess light untapped. Optimising incident light spectra is vital for high biomass production. Recent advancements have utilised fluorescent dyes as spectral converters to improve PAR availability in algae. The current study evaluated the solubility and spectral profiles of Diphenylanthracene [DPA], Diphenyloxazole [DPO], Rhodamine 6G [R6G], Rhodamine 8G [R8G], Rhodamine 800 [R800], Fluorescein Isothiocyanate [FITC], Lumogen Yellow [LY], and Lumogen Red [LR] in methanol, ethanol, and acetone across varying concentrations. DPA and DPO absorbed UV light and emitted in violet/blue wavelengths. In contrast, R8G emitted light in the blue-green region (450–500 nm), which could potentially stimulate pigment and lipid production in algae. LY exhibited peaks covering green to red PAR wavelengths. LR dye displayed an excitation/emission range of 320–400 and 590–660 nm, whereas R6G, R800, and FITC showed no PAR-related emissions. Most dyes showed higher fluorescence at 10 mgL−1 in methanol. DPA, LY, and R8G displayed the highest energy emissions, with LR emitting 9.56 × 10−18 J·photon−1, suggesting its potential to supply ample energy for supporting algal growth. This spectral conversion strategy shows promise for enhancing microalgae growth and metabolite production, reducing reliance on artificial light, and potentially cutting energy and cultivation costs. The study contributes to advancing sustainable practices in algal biotechnology.

Inorganic metal oxide‐reinforced polymer‐based flexible inorganic nanocomposite for UV shielding applications

AbstractThis investigation reveals the successful incorporation of strontium‐doped thorium oxide (SrThO3) NPs into polyvinyl alcohol (PVA) polymer nanocomposites. The fabrication process of these PVA nanocomposites entails utilizing varying amounts (0.5, 1.0, 2.0, and 4.0 wt%) of SrThO3 nanofillers through a straightforward solution casting technique. The microstructure and overall structure of the resulting polymer nanocomposites were analyzed using powdered x‐ray diffraction for crystalline structure and Fourier transform infrared (FTIR) spectroscopy for molecular composition. The introduced SrThO3 nanofiller demonstrates a strong affinity for the hydroxyl groups present in the PVA polymer, a phenomenon validated through FTIR spectroscopy. In order to comprehend the impact of doping, the surface morphology of the PVA polymer nanocomposites underwent examination via scanning electron microscopy. The absorption and transmission of light were quantitatively assessed using UV–visible spectroscopy. The excitation and emission behaviors of electrons in both the PVA and SrThO3‐doped PVA nanocomposites were scrutinized through photoluminescence spectroscopy. Furthermore, the extent of UV light absorption was investigated by studying the degradation of methylene blue dye, a substance known for its sensitivity to UV light. Results indicate that the intentional incorporation of SrThO3 NPs significantly enhances UV stability.

Benzimidazole derivatives as a new scaffold of anticancer agents: Synthesis, optical properties, crystal structure and DFT calculations

The absolute necessity to fight some class of tumour is perceived as serious health concerns, and the discovery and development of effective anticancer agents are urgently needed. So, the novel benzimidazole derivatives (2a-b) were designed, synthesized, with their structures rigorously characterized using single X-ray crystallography, FT-IR, UV, and NMR spectroscopy, alongside elemental analysis. The geometric structures were optimized using density functional theory (DFT) calculations performed at the ωB97X-D/cc-pVDZ level, yielding good agreement with experimental XRD data. The studied salt complexes exhibited the ability to absorb UV light at 275 nm. Furthermore, anticancer activity of the compounds was screened against (MDA-MB-231, MCF-7, HT-29 and healthy cell line (HF)) and revealed the remarkable efficacy of select newly synthesized Benzimidazole derivatives (2a-b). Compound 2a showed relative significant higher cytotoxicity (165.02) in MDA-MB-231 cancer cell line. This underscores their promising potential in therapeutic applications, affirming their role as valuable contenders in the pursuit of novel anticancer agents.

Influence of ZnO and Pr6O11 incorporation on the structural, thermal, optical, mechanical, and magnetic properties of calcium lithium borate glasses

A new glass of calcium lithium borate with the chemical formula (62.75-x)B2O3 + 20CaO + 0.25Pr6O11 + 17Li2O + xZnO, where x = 0, 2.5, 5, 10, 20 (mol%) have been prepared by conventional melt-quenching process. The amorphous character has been confirmed by the very short-range ordering structural matrices demonstrated through X-ray diffraction.The Raman spectra of the prepared glass revealed an enhancement of host lattice distortions. Differential scanning calorimetry (DSC) estimated the glass transition temperature (Tg), the onset temperature of crystallization (Tc), and the melting temperature (Tm). The glass transition decreased from 441 °C to 431 °C with increasing ZnO content up to 10 mol%. The criteria of glass samples up to 10 % ZnO have higher strength, rigidity and higher level of thermal stability. The physical quantities as density, molar volume, inter-atomic distance, polaron radius, packing density, and oxygen packing density were calculated. The glass density increases while the molar volume decreases with ZnO content. The optical properties of glasses were investigated using UV–Vis spectrophotometer. The addition of ZnO enhances the light absorption in UV–Vis. The results of the calculated direct and indirect optical band gaps decrease from 3.663 eV to 3.233 eV for and from 3.167 eV to 2.648 eV for direct and indirect transitions respectively with the increment of ZnO addition. Additionally, the dispersion energy and static refractive index clearly increase while the oscillator energy declines. The Makishima-Mackenzie’s (M−M) method was employed to ascertain mechanical parameters, including elastic moduli, and Poisson’s ratio. The study revealed an enhancement to the mechanical properties as the content of ZnO increased. Vibrating sample magnetometer (VSM) was used to investigate the magnetic properties of the prepared glass and all samples exhibited a ferromagnetic behavior. The incorporation of ZnO act as glass modifier controlling their physical, optical and mechanical properties making the investigated glasses suitable for various applications.

Impedance spectroscopy investigation on the electrical response and optical characteristics of novel Sr2TiZrO6 double perovskite

This study centers on the synthesis and characterization of a novel double perovskite, termed Sr2TiZrO6 (STZO), which was synthesized using the conventional solid-state reaction method and subsequently calcined at 1000 °C for 12 h. X-ray diffraction (XRD) pattern refinement confirmed the formation of the tetragonal phase Sr2TiZrO6 (space group P4mm), while both XRD and scanning electron microscope (SEM) analyses revealed that the resulting STZO displaying spherical-like grains with nanometric diameters. Thermogravimetric analysis revealed a minor weight loss attributed to the emergence of the ZrO2 phase and the formation of the STZO double perovskite. The diffuse reflectance spectroscopy (DRS) results demonstrated strong UV-light absorption, with an optical absorption onset below 400 nm. The obtained band gap for direct transitions of the STZO sample is equal to 3.26 eV. The conductance and impedance study of the STZO sample are investigated. The present properties provide crucial insights to enhance comprehension of the STZO double perovskite material, which holds promise as a viable candidate for a range of applications, such as solar cells and photodiodes.

Revolutionary composites of silver and zinc oxide nanoparticles from Hardwickia binata: Unleashing their potent antioxidant and anticancer properties

In the present of the study, was utilized the leaf extract of H. binata to synthesize Ag-ZnO nanocomposites. The nanocomposites were characterized using various techniques, including UV, FTIR, XRD and SEM-EDX. Nanocomposites are known for their promising properties, such as mechanical, thermal, electrical and optical characteristics, which have attracted significant attention from both academia and industry, resulting in active research in various fields. The introduction of silver (Ag) into the nanocomposites enabled them to exhibit UV light absorption at 366 nm, while the presence of zinc confirmed the peak at 431 nm. XRD analysis was carried out to determine the crystal structure and composition of the materials. The antibacterial properties of the Ag-ZnO nanocomposites were evaluated using the disc diffusion method, revealing the highest inhibition against the bacteria strain Bacillus subtilis (19 mm) compared to other strains. Furthermore, the nanocomposites demonstrated strong antioxidant activity against DPPH (56%), ABTS (59%) and exhibited anti-inflammatory activity (62%). Additionally, the Ag-ZnO nanocomposites showed promising anti-cancer properties, as evidenced by their effectiveness against a skin cancer cell line (A431-69%). Moreover, the nanocomposites displayed significant photocatalytic activity, resulting in a 70% degradation rate. Overall, this study successfully synthesized Ag-ZnO nanocomposites that exhibited robust antibacterial, antioxidant, anti-inflammatory and anticancer properties. These findings suggest the potential application of these nanocomposites in cancer treatment and environmental studies, particularly in dye degradation.

Effect of Surface Functional Groups on the Electronic Behavior and Optical Spectra of Mn2N Based MXenes.

The extensive applications of MXenes, a novel type of layered materials known for their favorable characteristics, have sparked significant interest. This research focuses on investigating the influence of surface functionalization on the behavior of Mn2NTx (Tx=O2, F2) MXenes monolayers using the "Density functional theory (DFT) based full-potential linearized augmented-plane-wave (FP-LAPW)" method. We elucidate the differences in the physical properties of Mn2NTx through the influence of F and O surface functional groups. We found that O-termination results in half-metallic behavior, whereas the F-termination evolves metallic characteristics within these MXene systems. Similarly, surface termination has effectively influenced their optical absorption efficiency. For instance, Mn2NO2 and Mn2NF2 effectively absorb UV light ~50.15×104 cm-1 and 37.71×104 cm-1, respectively. Additionally, they demonstrated prominent refraction and reflection characteristics, which are comprehensively discussed in the present work. Our predictions offer valuable perspectives into the optical and electronic characteristics of Mn2NTx-based MXenes, presenting the promising potential for implementing them in diverse optoelectronic devices.

Elaboration and Characterization of CdS Nanostructures Using Pulse‐Assisted Electrodeposition: Effect of Time‐Off Duration

The presence of metallic cadmium in the electrodeposited cadmium sulfide (CdS) films is a persistent problem that leads to low photoactivity. Changing the deposition mode is a way to address this problem and thus increase the photoelectrochemical performance. Herein, the effect of the deposition mode on the composition of the CdS films prepared under the same deposition parameters is investigated for the first time. In addition, the influence of the time‐off duration on the properties of the electrodeposited thin films is studied. The results of the X‐Ray diffraction, UV–vis spectroscopy, atomic force microscopy, and photoelectrochemical characterizations reveal that the pulse‐deposited CdS films show enhanced microstructural, optical, and morphological properties as compared to that of the film deposited under direct mode. The CdS thin film deposited at time‐off duration of 0.5 s is composed of a pure CdS phase following a mixture of cubic and hexagonal lattice structure. This sample shows a smooth surface, high absorption in UV and visible light and an intense photoresponse of 90 μA under visible light.

Visible light radical photoinitiators of polymerization based on photochromic molecules

A series of photochromic compounds linked to a benzophenone nucleus were synthetized and evaluated regarding their ability to act as Norrish type II radical photoinitiators, promoting the polymerization of a polyacrylate monomer after the consecutive absorption of LED UV and Vis light.

Harnessing the Synergetic Effects of Ag, Mn Dopants in Eco-Friendly Ultraviolet Selective Quantum Dots for Luminescent Solar Concentrators.

Quantum dots (QDs) are promising building blocks for luminescent solar concentrators (LSCs), yet most QD-based LSCs suffer from toxic metal composition and color tinting. UV-selective harvesting QDs can enable visible transparency, but their development is restricted by large reabsorption losses and low photoluminescence quantum yield (PLQY). The developed here Ag, Mn: ZnInS2/ZnS QDs show a high PLQY of 53% due to the passivating effect of ZnS shell. These QDs selectively absorb UV light and emit orange-red light with a large Stokes shift of 180nm. A LSC of 5×5×0.2cm3, fabricated using a poly(lauryl methacrylate) (PLMA) as a matrix, maintains 87% of integrated PL after 7h of UV exposure. The QD-PLMA achieved 90.7% average visible transparency (AVT) and a color rendering index (CRI) of 95.8, which is close to plain PLMA (AVT=90.8%; CRI=99.5), yielding excellent visible light transparency. Incorporating Si-PVs at LSC edges, the Ag, Mn: ZIS/ZnS QD-LSC achieved an optical efficiency of 1.42%, ranking competitively among high-performing UV-harvesting LSCs.

Dual-Responsive Gradient Structured Actuator via Photopolymerization-Induced Diffusion.

Stimuli-responsive materials have recently gained significant attention in the field of soft robotics, sensors, and biomimetic devices. The most facile way for the fabrication of such materials remains to endow bilayer structures which are fabricated with the combination of active and passive layers. Although, easily fabricated, these structures suffer from the generation of stress points between connection areas. In this work we develop a method to create a thin film with controlled cross-link variation across its thickness. The cross-link gradient is achieved through polymerization induced diffusion of dithiol molecules in thiol-ene network. As a result, the film exhibits bending deformation upon illumination with light or exposure to a chemical solvent, thereby demonstrating dual responsiveness. Light actuation of the film is achieved via photothermal effects due to the incorporation of dye into the system which can absorb UV light and heat the network. While solvent induced actuation is due to anisotropic swelling. Furthermore, the straightforward fabrication procedure allows for the creation of more complex deformations by patterning the film using a photomask during photopolymerization.

FeNi-MIL-88B-based electrochemiluminescence immunosensor for ultra-sensitive detection of CD44 protein via dual-quenching strategy

BackgroundCluster of Differentiation 44 (CD44) is considered an important biomarker for various cancers, and achieving highly sensitive detection of CD44 is crucial, which plays a significant role in tumor invasion and metastasis, providing essential information for clinical tumor diagnosis. Commonly used methods for analysis include fluorescence spectroscopy (FL), photoelectrochemical analysis (PEC), electrochemical analysis (EC), and commercial ELISA kits. Although these methods offer high sensitivity, they can be relatively complex to perform experimentally. Electrochemiluminescence (ECL) has gained widespread research attention due to its high sensitivity, ease of operation, effective spatiotemporal control, and close to zero background signal. ResultsIn this work, a sandwich-type ECL immunosensor for detecting CD44 was constructed using luminol as a luminophore. In this sensing platform, bimetallic MOFs (Pd@FeNi-MIL-88B) loaded with palladium nanoparticles (Pd NPs) were used as a novel enzyme mimic, exhibiting excellent catalytic performance towards the electroreduction of H2O2. The hybrids provided a strong support platform for luminol and antibodies, significantly enhancing the initial ECL signal of luminol. Subsequently, core-shell Au@MnO2 nanocomposites were synthesised by gold nanoparticles (Au NPs) encapsulated in manganese dioxide (MnO2) thin layers, as labels. In the luminol/H2O2 system, Au@MnO2 exhibited strong light absorption in the broad UV–vis spectrum, similar to the black body effect, and the scavenging effect of Mn2+ on O2•−, which achieved the dual-quenching of ECL signal. Under the optimal experimental conditions, the immunosensor demonstrated a detection range of 0.1 pg mL−1 − 100 ng mL−1, with a detection limit of 0.069 pg mL−1. SignificanceBased on Pd@FeNi-MIL-88B nanoenzymes and Au@MnO2 nanocomposites, a dual-quenching sandwich-type ECL immunosensor for the detection of CD44 was constructed. The proposed immunosensor exhibited excellent reproducibility, stability, selectivity, and sensitivity, and provided a valuable analytical strategy and technical platform for the accurate detection of disease biomarkers, and opened up potential application prospects for early clinical treatment.