Fe(III)-quenched cysteine-capped copper nanoclusters as a selective fluorescence turn-on sensor for valine: A potential cancer biomarker candidate

This study introduces a fluorescence turn-on sensor for the selective detection of valine, an amino acid increasingly recognized as a potential biomarker in cancer diagnostics, using iron(III) (Fe3+) quenched L-cysteine capped copper nanoclusters (L-cys@CuNCs) based on the paramagnetic quenching mechanism of Fe3+. The L-cys@CuNCs, synthesized through a one-pot hydrothermal method, exhibit stable green fluorescence, high photostability and a detection limit of 3.00 µM for valine. Restoration of fluorescence upon interaction with valine enables a highly sensitive detection, with strong selectivity against other amino acids and ions. This specificity makes the sensor particularly promising for screening valine in biological samples, supporting its potential as a non-invasive cancer biomarker. To enhance practicality, a paper-based assay was developed, demonstrating its adaptability to point of care formats. Additionally, testing in human saliva and urine samples validated the probe's utility in real biological conditions, underscoring its potential in non-invasive cancer diagnostics. This biosensing platform offers a rapid, accessible tool for valine detection, contributing to early cancer detection and patient screening in clinical and resource limited settings.

Fluorescence Turn-On Sensing of Leucine Using Bimetallic Cu-Ag Nanoclusters: A Potential Non-Invasive Biomarker for Cancer Detection

This study investigates the use of bimetallic copper-silver nanoclusters (Cu-AgNCs) for fluorescence turn-on sensing of leucine, a potential biomarker for cancer detection. These nanoclusters exhibit high fluorescence tunability and specificity, with Fe3+ serving as a quencher to facilitate leucine detection. The fluorescence recovery mechanism is attributed to the interaction of leucine with Fe3+, alleviating the quenching effect on the metal nanoclusters. This bimetallic nanocluster is a promising platform for biomarker identification in cancer diagnosis. The fluorescence enhancement upon leucine binding provides a measurable signal, confirming the feasibility of these nanoclusters as noninvasive sensors for cancer biomarkers. The sensor achieves a detection limit of 0.58 μM and demonstrates a linear response within the range of 110-657 μM. This approach offers a promising method for noninvasive cancer diagnostics using saliva and urine samples. Additionally, the method's reproducibility and robustness further support its potential in clinical applications, providing a cost-effective and accessible technique for early cancer detection.

All-In-One Additive Enabled Efficient and Stable Narrow-Bandgap Perovskites for Monolithic All-Perovskite Tandem Solar Cells

Hybrid tin-lead (Sn-Pb) perovskites have garnered increasing attention due to their crucial role in all-perovskite tandem cells for surpassing the efficiency limit of single-junction solar cells. However, the easy oxidation of Sn2+ and fast crystallization of Sn-based perovskite present significant challenges for achieving high-quality hybrid Sn-Pb perovskite films, thereby limiting the device's performance and stability. Herein, an all-in-one additive, 2-amino-3-mercaptopropanoic acid hydrochloride (AMPH) is proposed, which can function as a reducing agent to suppress the formation of Sn4+ throughout the film preparation. Furthermore, the strong binding between AMPH and Sn-based precursor significantly slows down the crystallization process, resulting in a high-quality film with enhanced crystallinity. The remaining AMPH and its oxidation products within the film contribute to improves oxidation resistance and a substantial reduction in defect density, specifically Sn vacancies. Benefiting from the multifunctionalities of AMPH, a power conversion efficiency (PCE) of 23.07% is achieved for single-junction narrow-bandgap perovskite solar cells. The best-performing monolithic all-perovskite tandem cell also exhibits a PCE of 28.73% (certified 27.83%), which is among the highest efficiency reported yet. The tandem devices can also retain over 85% of their initial efficiencies after 500 hours of continuous operation at the maximum power point under one-sun illumination.

Synthesis, kinetics, mechanisms, and bioactivity evaluations of a novel Zn(ii) complex

Zn(ii)-based anticancer drugs can be suitable alternatives to conventional Pt(ii)-based drugs because of the unique chemical properties of Zn(ii) and low toxicity. In this study, a new hexadentate and heteroleptic Zn(ii) complex ([Zn(bpy)2(OAc)2], 1) was prepared with a conventional N,N-donor ligand (2,2'-bipyridine) and a leaving group (OAc) and characterized via ESI-MS, UV-Vis, and FT-IR spectroscopy. Kinetic and mechanistic investigations of 1 were performed using two biologically relevant ligands (dl-penicillamine and l-cysteine) to understand its selectivity and reactivity. Substitution reactions were determined to be two-step processes in the associative activation mode. Bioactivity studies of 1 revealed moderate to strong DNA-binding, cleaving ability, and antimicrobial properties.

Study of Brewer's Spent Grain Environmentally Friendly Processing Ways

BACKGROUND

This article is devoted to the study of the effect of electrochemically activated water (catholyte with pH 9.3) on organic compounds of the plant matrix of brewer's spent grain in order to extract various compounds from it.

METHODS

Brewer's spent grain was obtained from barley malt at a pilot plant by mashing the malt followed by filtration and washing of the grain in water and storing it at (0 ± 2) °C in craft bags. For the organic compound quantitative determination, instrumental methods of analysis (HPLC) were used, and the results were subjected to mathematical analysis.

RESULTS

The study results showed that at atmospheric pressure, the alkaline properties of the catholyte showed better results compared to aqueous extraction with respect to β-glucan, sugars, nitrogenous and phenolic compounds, and 120 min was the best period for extraction at 50 °C. The excess pressure conditions used (0.5 ÷ 1 atm) revealed an increase in the accumulation of non-starch polysaccharide and nitrogenous compounds, while the level of sugars, furan and phenolic compounds decreased with increasing treatment duration. The waste grain extract ultrasonic treatment used revealed the effectiveness of catholyte in relation to the extraction of β-glucan and nitrogenous fractions; however, sugars and phenolic compounds did not significantly accumulate. The correlation method made it possible to reveal the regularities in the formation of furan compounds under the conditions of extraction with the catholyte: Syringic acid had the greatest effect on the formation of 5-OH-methylfurfural at atmospheric pressure and 50 °C and vanillic acid under conditions of excess pressure. Regarding furfural and 5-methylfurfural, amino acids had a direct effect at excess pressure. It was shown that the content of all furan compounds depends on amino acids with thiol groups and gallic acid; the formation of 5-hydroxymethylfurfural and 5-methylfurfural is influenced by gallic and vanillic acids; the release of furfural and 5-methylfurfural is determined by amino acids and gallic acid; excess pressure conditions promote the formation of furan compounds under the action of gallic and lilac acids.

CONCLUSIONS

This study showed that a catholyte allows for efficient extraction of carbohydrate, nitrogenous and monophenolic compounds under pressure conditions, while flavonoids require a reduction in extraction time under pressure conditions.

Electric Double Layer: The Good, the Bad, and the Beauty

The electric double layer (EDL) is the most important region for electrochemical and heterogeneous catalysis. Because of it, its modeling and investigation are something that can be found in the literature for a long time. However, nowadays, it is still a hot topic of investigation, mainly because of the improvement in simulation and experimental techniques. The present review aims to present the classical models for the EDL, as well as presenting how this region affects electrochemical data in everyday experimentation, how to obtain and interpret information about EDL, and, finally, how to obtain some molecular point of view insights on it.

Long Shelf-Life Efficient Electrolytes Based on Trace l-Cysteine Additives toward Stable Zinc Metal Anodes

The unstable anode/electrolyte interface (AEI) triggers the corrosion reaction and dendrite formation during cycling, hindering the practical application of zinc metal batteries. Herein, for the first time, l-cysteine (Cys) is employed to serve as an electrolyte additive for stabilizing the Zn/electrolyte interface. It is revealed that Cys additives tend to initially approach the Zn surface and then decompose into multiple effective components for suppressing parasitic reactions and Zn dendrites. As a consequence, Zn|Zn symmetric cells using trace Cys additives (0.83 mm) exhibit a steady cycle life of 1600 h, outperforming that of prior studies. Additionally, an average Coulombic efficiency of 99.6% for 250 cycles is also obtained under critical test conditions (10 mA cm^-2 /5 mAh cm^-2 ). Cys additives also enable Zn-V₂ O₅ and Zn-MnO₂ full cells with an enhanced cycle stability at a low N/P ratio. More importantly, Cys/ZnSO₄ electrolytes are demonstrated to be still effective after resting for half year, favoring the practical production.

Chemically characterizing the cortical cell nano-structure of human hair using atomic force microscopy integrated with infrared spectroscopy (AFM-IR)

OBJECTIVE

The use of conventional microscopy and vibrational spectroscopy in the optical region to investigate the chemical nature of hair fibres on a nanometre scale is frustrated by the diffraction limit of light, prohibiting the spectral elucidation of nanoscale sub-structures that contribute to the bulk properties of hair. The aim of this work was to overcome this limitation and gain unprecedented chemical resolution of cortical cell nano-structure of hair.

METHODS

The hybrid technique of AFM-IR, combining atomic force microscopy with an IR laser, circumvents the diffraction limit of light and achieves nanoscale chemical resolution down to the AFM tip radius. In this work, AFM-IR was employed on ultra-thin microtomed cross-sections of human hair fibres to spectrally distinguish and characterize the specific protein structures and environments within the nanoscale components of cortical cells.

RESULTS

At first, a topographical and chemical distinction between the macrofibrils and the surrounding intermacrofibillar matrix was achieved based on 2.5 × 2.5 μm maps of cortical cell cross-sections. It was found that the intermacrofibrillar matrix has a large protein content and specific cysteine-related residues, whereas the macrofibrils showed bigger contributions from aliphatic amino acid residues and acidic-/ester-containing species (e.g. lipids). Localized spectra recorded at a spatial resolution of the order of the AFM tip radius enabled the chemical composition of each region to be determined following deconvolution of the Amide-I and Amide-II bands. This provided specific evidence for a greater proportion of α-helices in the macrofibrils and correspondingly larger contributions of β-sheet secondary structures in the intermacrofibrillar matrix, as inferred in earlier studies. Analysis of the parallel and antiparallel β-sheet structures, and of selected dominant amino acid residues, yielded further novel composition and conformation results for both regions.

CONCLUSION

In this work, we overcome the diffraction limit of light using atomic force microscopy integrated with IR laser spectroscopy (AFM-IR) to characterize sub-micron features of the hair cortex at ultra-high spatial resolution. The resulting spectral analysis shows clear distinctions in the Amide bands in the macrofibrils and surrounding intermacrofibrillar matrix, yielding novel insight into the molecular structure and intermolecular stabilization interactions of the constituent proteins within each cortical component.

Ceftizoxime loaded ZnO/L-cysteine based an advanced nanocarrier drug for growth inhibition of Salmonella typhimurium

l-Cysteine coated zinc oxide (ZnO) nano hollow spheres were prepared as a potent drug delivery agent to eradicate Salmonella enterica serovar Typhimurium (S. typhimurium). The ZnO nano hollow spheres were synthesized by following the environmentally-friendly trisodium citrate assisted method and l-cysteine (L-Cys) conjugate with its surface. ZnO/L-Cys@CFX nanocarrier drug has been fabricated by incorporating ceftizoxime with L-Cys coated ZnO nano hollow spheres and characterized using different techniques such as scanning electron microscope (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), and X-ray diffraction (XRD) etc. Furthermore, the drug-loading and encapsulation efficiency at different pH levels was measured using UV–vis spectrometer and optimized. A control and gradual manner of pH-sensitive release profile was found after investigating the release profile of CFX from the carrier drug. The antibacterial activity of ZnO/L-Cys@CFX and CFX were evaluated through the agar disc diffusion method and the broth dilution method, which indicate the antibacterial properties of antibiotics enhance after conjugating. Surprisingly, the ZnO/L-Cys@CFX exhibits a minimum inhibitory concentration (MIC) of 5 µg/ml against S. typhimurium is lower than CFX (20 µg/ml) itself. These results indicate the nanocarrier can reduce the amount of CFX dosed to eradicate S. typhimurium.

Oxidation of Cysteinate Anions Immobilized in the Interlamellar Space of CaAl-Layered Double Hydroxide

L-Cysteinate-intercalated CaAl-layered double hydroxide (LDH) was prepared by the co-precipitation method producing highly crystalline hydrocalumite phase with a well-pillared interlayer gallery. The obtained materials were characterized by X-ray diffractometry, IR as well as Raman spectroscopies. By performing interlamellar oxidation reactions with peracetic acid as oxidant, oxidation of cysteinate to cystinate in aqueous and cysteinate sulfenic acid in acetonic suspensions occurred. The oxidations could be performed under mild conditions, at room temperature, under neutral pH and in air. It has been shown that the transformation pathways are due to the presence of the layered structure, that is, the confined space of the LDH behaved as molecular reactor.

Mustards-Derived Terpyridine-Platinum Complexes as Anticancer Agents: DNA Alkylation vs Coordination

The development of bifunctional platinum complexes with the ability to interact with DNA via different binding modes is of interest in anticancer metallodrug research. Therefore, we report platinum(II) terpyridine complexes to target DNA by coordination and/or through a tethered alkylating moiety. The platinum complexes were evaluated for their in vitro antiproliferative properties against the human cancer cell lines HCT116 (colorectal), SW480 (colon), NCI-H460 (non-small cell lung), and SiHa (cervix) and generally exhibited potent antiproliferative activity although lower than their respective terpyridine ligands. ¹H NMR spectroscopy and/or ESI-MS studies on the aqueous stability and reactivity with various small biomolecules, acting as protein and DNA model compounds, were used to establish potential modes of action for these complexes. These investigations indicated rapid binding of complex PtL3 to the biomolecules through coordination to the Pt center, while PtL4 in addition alkylated 9-ethylguanine. PtL3 was investigated for its reactivity to the model protein hen egg white lysozyme (HEWL) by protein crystallography which allowed identification of the N^δ1 atom of His15 as the binding site.

Nanoscale Molecular Characterization of Hair Cuticle Cells Using Integrated Atomic Force Microscopy-Infrared Laser Spectroscopy

The hair cuticle provides significant protection from external sources, as well as giving rise to many of its bulk properties, e.g., friction, shine, etc. that are important in many industries. In this work, atomic force microscopy-infrared spectroscopy (AFM-IR) has been used to investigate the nanometer-scale topography and chemical structure of human hair cuticles in two spectral regions. AFM-IR combines atomic force microscopy with a tunable infrared laser and circumvents the diffraction limit that has impaired traditional infrared spectroscopy, facilitating surface-selective spectroscopy at ultra-spatial resolution. This high resolution was exploited to probe the protein secondary structures and lipid content, as well as specific amino acid residues, e.g., cystine, within individual cuticle cells. Characterization across the top of individual cells showed large inhomogeneity in protein and lipid contributions that suggested significant changes to physical properties on approaching the hair edge. Additionally, the exposed layered sub-structure of individual cuticle cells allowed their chemical compositions to be assessed. The variation of protein, lipid, and cystine composition in the observed layers, as well as the measured dimensions of each, correspond closely to that of the epicuticle, A-layer, exocuticle, and endocuticle layers of the cuticle cell sub-structure, confirming previous findings, and demonstrate the potential of AFM-IR for nanoscale chemical characterization within biological substrates.

Chemistry of cysteine assembly on Au(100): electrochemistry, in situ STM and molecular modeling

Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of l-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol cm-2 were observed. In situ STM showed that the adsorbed Cys is organized in stripes with "fork-like" features which co-exist in (11 × 2)-2Cys and (7 × 2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure l-Cys and pure d-Cys and a 1 : 1 racemic mixture of l- and d-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of l- and d-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of the adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.

The long and successful journey of electrochemically active amino acids. From fundamental adsorption studies to potential surface engineering tools

Proteins have been the subject of electrochemical studies. It is possible to apply electrochemical techniques to obtain information about their structure due to the presence of five electroactive amino acids that can be oriented to the outside of the peptidic chain. These amino acids are L-Tryptophan (L-Trp), L-Tyrosine (L-Tyr), L-Histidine (L-His), L-Methionine (L-Met) and L-Cysteine (L-Cys); their electrochemical behavior being subject of extensive research, but it is still controversial. No spectroscopic investigations have been reported on L-Trp, and due to the short life time of the intermediates, ex situ techniques cannot be employed, leading to a never-ending discussion about possible intermediates. In the L-Tyr and L-His cases, spectroelectrochemical studies were performed and different intermediates were observed, suggesting that some intermediates may be observed under specific conditions, as proposed for L-Cys. This amino acid is the most interesting among the electroactive ones because of the presence of a thiol moiety at its side chain, leading to a wide range of oxidation states. It can adsorb onto surfaces of different crystallographic orientation in stereoselective conformation, modifying the surface for different applications.as a surface engineering tool since it plays the role of as an anchor for the growing of nanocrystals inside proteic templates.