UV-vis Absorption Spectroscopy Research Articles

Green synthesis of chitosan/glutamic acid/agarose/Ag nanocomposite hydrogel as a new platform for colorimetric detection of Cu ions and reduction of 4-nitrophenol

In this study, the green synthesis of chitosan/glutamic acid/agarose/Ag (Chi/GA/Aga/Ag) nanocomposite hydrogel was obtained via in situ reduction of Ag ions during the crosslinking process of chitosan-agarose double network hydrogels. The rich hydroxyl, carboxyl and amino groups in both agarose, chitosan, and glutamic acid can effectively control the growth, dispersion and immobilization of nearly spherical Ag nanoparticles (70 nm) in the Chi/GA/Aga/Ag composite hydrogel. Glutamic acids can act as the structure-directing agents to induce the formation of chitosan/glutamic acid hydrogel. The mechanical strength of the Chi/GA/Aga/Ag composite hydrogel can be enhanced by the introduction of chitosan-agarose double network hydrogels, which guarantees that it can be directly used as a visual test strip of the Cu ions with a lower detection limit of 1 μM and an active catalyst for the reduction of 4-nitrophenol within 18 min. The quantitative and semi-quantitative measurement of Cu ions can be carried out by UV–visible absorption spectroscopy and visual measurement, which provided a convenient, portable, and “naked-eye” solid-state detection methodology.

Synthesis and characterization of Dy-doped Zn2SiAl2O4 nanophosphor for color modulation in advanced lighting systems

Nanoparticles of Zn2SiAl2O4 infused with Dy3+ were produced through a traditional co-precipitation approach. We investigated the particles' structural attributes and physical characteristics using tools such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV–Vis absorption spectroscopy, and photoluminescence (PL) spectrometry. The XRD outcomes validated the crystalline nature of the nanoparticles and showed the effective replacement of Dy3+ ions in the place of Zn2+ ions within the matrix and with increasing Dy concentration from 0.5 % to 1.25 %, the crystallite size decreased from 84 nm to 53 nm. The SEM visuals offered clarity on the shape, dimension, and spread of these particles. FTIR analysis further confirmed the composition and structure of the nanoparticles by identifying the chemical bonds and functional groups. UV–visible absorption spectroscopy revealed increase in the optical energy bandgap from 4.45 eV to 4.55 eV with increasing Dy3+ content, indicating potential for optical applications. The photoluminescence spectrometry results featured a prominent transition at approximately 646 nm, suggest that the phosphor has the capability to function as a vivid yellow light emitter and demonstrate their potential for application in optoelectronics, photonics, and luminescent materials.

Sodium lauryl sulphate-mediated synthesis: Unravelling the optimization path for enhanced stability and optical properties of cadmium sulphide nanoparticles

This research paper explores the synthesis of cadmium sulphide nanoparticles using sodium lauryl sulphate as a stabilizing agent through the co-precipitation method. The structural properties were investigated using X-ray diffractometry, while optical properties were analysed through UV–visible absorption spectroscopy. High-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy were employed to study the morphology and elemental mapping of the nanoparticles. The co-precipitation synthesis, synergized with sodium lauryl sulphate assisted stabilization, affords a scientific vantage point into the intricate mechanisms through which sodium lauryl sulphate intricately tailors the optical and stability profiles of nanoparticles. Additionally, the effects of different concentrations of sodium lauryl sulphate were examined to determine the optimal concentration for desired properties. The optimal concentration of 1.5 g yielded cadmium sulphide nanoparticles with desirable characteristics, featuring a band gap of 2.07 eV. The findings presented herein contribute significantly to advancing our understanding of sodium lauryl sulphate capped cadmium sulphide nanoparticles and highlight their potential application in enhancing photocatalyst efficiency.This research holds exciting prospects for the creation of eco-friendly and highly efficient innovations, with extensive implications for the environmental and industrial sectors.

Pyrazoloquinoline-based fluorescent sensor for the detection of Pb2+, Zn2+ and the realization of an OR-type optical logic gate

A novel derivative of 1H-pyrazolo[3,4-b]quinoline (PQ2OH) has been synthesized and investigated by means of fluorescence and UV–vis absorption spectroscopy. The emission properties of the studied compound are characterized by low fluorescence quantum yields and short fluorescence lifetimes owing to the photoinduced electron transfer process, which is particularly efficient in highly polar solvents. We have employed this process in the optical detection of bivalent cations like Zn2+, Cd2+, Mg2+, Co2+, Ni2+, Ca2+, Pb2+, and Cu2+. The compound exhibits good selectivity towards Pb2+ and Zn2+ with limits of detection of 1.07 × 10−6 M and 1.06 × 10−6 M, respectively. The optical response is based on the recovery of native green fluorescence from pyrazoloquinoline. The sensor is able to detect Pb2+ in river water solutions with good sensitivity and can mimic an OR-type optical logic gate in cooperation with Pb2+ and Zn2+.

Effect of zirconium oxide nanoparticles on thermal, optical, and radiation shielding properties of Bi2O3-B2O3-MnO2 glasses

This study has explored the DSC, UV–Vis absorption spectroscopy, gamma ray and neutron shielding properties of Bi2O3-B2O3-MnO2: ZrO2 glasses. It demonstrates a unique approach to photon shielding analysis using JENDL/PD-2016 photonuclear data and employs a validated spherical neutron model for neutron shielding. Five transparent glasses were prepared with the chemical composition (in mol%) of 29Bi2O3-70B2O3-(1-x)MnO2: xZrO2, and labeled as MZ0.00 (for x = 0), MZ0.25 (for x = 0.25), MZ0.50 (for x = 0.5), MZ0.75 (for x = 0.75) and MZ1.00 (for x = 1). The glass ceramic nature of the samples has been characterized by DTA thermograms. The glass forming ability parameters (Kgl, S & H) were found to be highest for the sample MZ1.00. The UV–Visible optical absorption spectra have been interpreted, and hence the cut-off wavelength (λcut-off) and optical band gap (Eo) were evaluated. The absorption spectra have revealed the co-existence of manganese ions in three stable valence states Mn4+, Mn3+ and Mn2+ in the samples. When ZrO2 nanoparticles were added in the composition up to x = 0.50 mol%, the red shift in the cut-off wavelength (λcut-off) with gradual shrinkage in optical band gap (Eo) has been observed. Also, the linear and non-linear optical parameters viz., refractive index (no), non-linear refractive index (n2), linear optical susceptibility (χ(1)) and non-linear optical susceptibility (χ(3)) have been evaluated. These parameters showcased that B-O, Bi-O, Mn-O, Zr-O, etc. bonds could be strengthened by subsequent reduction of polarization of the trivalent ions (B3+ ions, Bi3+ ions and Mn3+ ions) in the glass system at higher concentrations of ZrO2. Photoatomic and photonuclear attenuation studies portrayed that the sample MZ0.50 has the lowest photon shielding capability. The fast neutron effective removal cross section (ΣR) was observed to be the highest for the sample MZ1.00. Thus, these glasses can be used to design the thermally stable transparent glasses, tunable optical elements, and radiation shielding materials.

Molecular interaction of antiviral drug penciclovir with DNA and HSA insights from experimental and docking studies

One approach to accelerate the availability of new cancer drugs is to test drugs approved for other conditions as anticancer agents. During recent decades, penciclovir (PNV) has been frequently utilized as a potent antiviral drug, in particular against infections caused by herpes viruses. Many antivirals interact with DNA and change their expression level, so determining the binding mode is of great importance. In our laboratory, we have focused our attention to design improved drugs that target cellular DNA, to understand the mechanism of action at the molecular level, and also to investigate the effect of antiviral drugs as anticancer agents. The results of ct-DNA-PNV interactions at physiological pH using fluorescence spectroscopy, UV–visible absorption spectroscopy, and molecular modeling reveal this drug binds well to ct-DNA through groove binding. The circular dichroism measurements displayed that PNV caused a slight change in the DNA structure which affirmed that the binding of PNV with the DNA occurs through the groove mode. Besides, multi-spectroscopic and molecular docking were used to evaluate how PNV interacts with human serum albumin under physiological conditions. The findings of fluorescence quenching suggested that static quenching was involved in the spontaneous development of HSA-PNV complex through hydrophobic force. The docking simulation results validated the findings of spectroscopic techniques. Communicated by Ramaswamy H. Sarma

Study on the photovoltaic characteristics of solar cells based on PbS quantum dots and carbon counter electrode

Lead sulfide (PbS) quantum dots (QDs) with their customizable and precise energy levels, have emerged as highly promising photosensitizers in quantum dots sensitized solar cells (QDSSCs). This research focuses on fabricating high-performance QDSSCs anchored on PbS QDs sensitized mesoporous titania coated FTO electrodes. The PbS QDs were grown on mesoporous TiO2 through the Successive Ionic Layer Absorption and Reaction (SILAR) method. The optical properties were analyzed using UV–visible absorption spectroscopy, revealing that the SILAR cycles impacted the size and band gap of the PbS QDs. By analyzing the absorption data and the hyperbolic band model (HBM), the size of the PbS QDs were estimated to be 1.65 nm, 2.126 nm, 2.326 nm, 2.5692 nm, and 3.048 nm for 1 to 5 SILAR cycles, respectively. The effect of SILAR cycles was investigated, demonstrating a direct correlation between the number of SILAR cycles and the photovoltaic performance of the device. The maximum power conversion efficiency of 2.07 % was attained using 2 SILAR cycles, in contrast to 1.33 % and 1.63 % obtained with one and three SILAR cycles, respectively. Furthermore, impedance spectroscopy (IS), (Cs-V) (Rs-V) was employed at different frequencies, highlighting lowest series resistance for 2 SILAR cycles confirming its highest photovoltaic performance. Moreover, The utilization of a low-cost polysulfide electrolyte and carbon electrode has yielded superior or comparable outcomes compared to previously reported data.

Synthesis, optical and magnetic properties of Nd2O3/borate strontium fluoride glasses

The present work conducts the synthesis, thermal, optical, and magnetic characterization of (60-x)B2O3+20Li2O+20SrF2+ x Nd2O3 where x = 0, 0.5, 1, 1.5, 2 mol% glass samples. The samples were investigated via X-ray diffraction (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), UV–Vis absorption spectroscopy, and vibrating sample magnetometry (VSM). XRD patterns for borate strontium fluoride glass samples doped with Nd2O3 showed broad humps around 30 and 43°, indicating their amorphous structure. Raman spectra of glass samples indicated that as Nd3+ ions were added to the host matrix, there was an increase in Raman intensity due to bond breakdown and the development of more non-bridging oxygen (NBO) species. The DSC data of the borate strontium fluoride glass samples doped with Nd2O3 demonstrated that the glass transition temperature (Tg) generally increased. UV–Vis absorption spectra showed transitions in Nd3+ ions doped borate glasses that are associated with the bands at different wavelengths, attributed to 4G5/2+2G7/2, 2H11/2, 4F9/2, 2H9/2 +4F5/2, and 4F3/2. The refractive index of borate strontium fluoride glass samples doped with Nd2O3 increased. The saturation magnetization values decreased from 0.9 to 0.29 upon increasing the Nd2O3 percentage (0–2 mol%). These low saturation magnetization glass samples can be used in spintronic devices to effectively reduce switching current density and lower the damping constant.

Exploration of the impact of graphene oxide, acetylenic gemini, and CTAT on the photophysical and aggregation properties of dipolar coumarin 153.

Advanced spectroscopic techniques have been utilized to study the interaction between the laser dye coumarin 153 (C153) and graphene oxide (GO) nanoparticles. GO was synthesized using a modified Hummers' method and characterized by UV-vis spectroscopy, Raman laser spectroscopy, FTIR-ATR spectroscopy, FESEM, HR-TEM, and XRD techniques. The GO@C153 composite was formed by mixing two aqueous solutions of GO and C153 due to their strong interaction through stacking and hydrophobic interactions. In this case, GO acts as an effective fluorescence quencher for C153 molecules, which undergo H-type aggregation in the presence of GO. The Stern-Volmer equation and time-dependent fluorescence studies were utilized to analyse the mechanism of fluorescence quenching. According to the findings, both static and dynamic quenching processes are responsible for the reduction in fluorescence intensity. The effect of surfactants (both cetyltrimethylammonium p-toluenesulfonate (CTAT) and synthesized N,N'-dihexadecyl-N,N,N',N'-tetramethyl-N,N'-but-2-ynediyl-di-ammonium chloride (16-4-16)) on the aggregation and photophysical properties of the dye was investigated using surface tensiometry, conductometry, UV-vis absorption spectroscopy, steady-state fluorescence measurements, DLS, and time-dependent fluorescence spectroscopy. Surfactants change the microenvironment of the C153 dye, leading to spectrum shifting and a higher quantum yield, which causes a rapid rise in fluorescence intensity in the micellar medium. It has been noted that in a micellar medium rather than in an aqueous one, the luminous intramolecular charge transfer (ICT) state of C153 stabilises. Lastly, we investigated the photophysical behavior of the GO-C153-micelle ternary system and discovered that, in the presence of a micellar medium, the quenched and blue-shifted (H-type aggregation) fluorescence peak of C153 (in the presence of GO) began to intensify once more. The main goal of this work is to create an effective and fairly cost powerful fluorescence sensor. Additionally, the ternary system (GO-C153-micelle) analytical idea can be employed to identify the onset of micelle formation. In wastewater treatment analysis, the GO-C153-surfactant ternary system concept can also be used to regenerate the adsorbent (in this case, GO) from dye molecules by allowing the dye molecules to exit the adsorbent and enter the micellar medium.

Removal of bromophenol blue from polluted water using a novel azo-functionalized magnetic nano-adsorbent.

Water pollution from organic dyes poses a serious danger to the environment. In the present work, we report a novel adsorbent (ADFS) based on azo-dye-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of the anionic dye bromophenol blue (BPB) from contaminated water. The fabricated SPIONs, azo dye, and ADFS adsorbent were characterized with FTIR and UV-vis absorption spectroscopy, 1HNMR spectroscopy, mass spectrometry, SEM imaging, dynamic light scattering (DLS), zeta potential measurements, vibrating sample magnetometry, thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. DLS measurements showed a particle size of 46.1 and 176.5 nm for the SPIONs and the ADFS, respectively. The adsorbent exhibited an adsorption capacity of 7.43 mg g-1 and followed the pseudo-second-order kinetics model (r2 = 0.9981). The ADFS could efficiently remove BPB from water after stirring for 120 minutes at room temperature and pH 2. The adsorption process was proved to occur via physisorption, as revealed by the Freundlich isotherm (n = 1.82 and KF = 11.5). Thermodynamic studies implied that the adsorption is spontaneous (-8.03 ≤ ΔG ≤ -0.58 kJ mol-1) and enthalpy-driven might take place via van der Waals interactions and/or hydrogen bonding (ΔH = -82.19 kJ mol-1 and ΔS = -0.24 kJ mol-1 K-1).

Different solvents and organic modifiers for the control of crystallographic parameters in nano-crystallite hydroxyapatite for amplification of photocatalytic activity.

In this research, HAp nanocrystals were synthesized using conventional wet chemical precipitation methods using various organic modifiers, including urea, palmitic acid, and naphthalene. Ethanol and isopropyl alcohol (IPA) were used as solvents in this process. Different characterization techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy, were employed to ascertain the formation of HAp nanocrystals. Numerous structural parameters, including lattice parameters, unit cell size, volume of the unit cell, specific surface area, degree of crystallinity, dislocation density, macrostrain, and crystallinity index, were assessed using XRD data. The linear straight-line method of Scherrer's equation, Monshi-Scherrer's method, the Williamson-Hall method, the size-strain plot method, the Halder-Wagner method, and Sahadat-Scherrer's model were applied to compute the crystallite size of the synthesized HAp samples. All the synthesized HAp has crystalline structures within the permissible range of 1-150 nm which were estimated from the XRD data using the mentioned models. However, the values for strain (from -3 × 10-4 to 6.4 × 10-3), strain (from -9.599 × 104 to 7 × 1010 N m-2), and energy density (from -11 × 1011 to 2 × 107 J m-3) were also calculated for the synthesized samples. In addition, the optical band gap energy of the synthesized HAp was computed (5.89 to 6.19 eV). The synthesis media have a control on the crystallographic planes, e.g. in the case of the ethanol medium, the (110) plane exhibited significant intensity (which could potentially serve as a driving force for enhancing photocatalytic activity). The use of 100% ethanol HAp yields the most favorable outcome regarding both the degradation percentage (91.79%) and degradation capacity (7%) for the Congo red dye.

Highly selective detection of 2,4-dinitrophenol by fluorescent NH2-MIL-125(Ti) via dual-parameter sensing technology.

The organic contaminant 2,4-dinitrophenol (2,4-DNP) is widely prevalent and poses significant risks to human health. Although numerous in-depth studies having been reported on the highly sensitive detection of 2,4-DNP, there are still challenges to its selective detection. Here, the fluorescence intensity ratio (I0/I) and emission peak shift (Δλ) were utilized for selective detection of 2,4-DNP by NH2-MIL-125(Ti). Notably, the emission peak of the NH2-MIL-125(Ti) suspension exhibited a remarkable red shift in the presence of 2,4-DNP (Δλ = 26 nm), accompanied by the blue shift or weak red shift of analogs, which provided a solid basis for selective detection of 2,4-DNP. Meanwhile, the I0/I ratio of the NH2-MIL-125(Ti) suspension exhibited a robust linear correlation with 2,4-DNP at the low concentration range (0-70 μM). The interaction of the analyte with NH2-MIL-125(Ti) was revealed to involve intermolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET) through XPS, FTIR, and UV-vis absorption spectroscopy. Additionally, we achieved the detection of 2,4-DNP using a smartphone by recognizing both the blue (B) values and the luminance (L) values. The obtained results demonstrated that the NH2-MIL-125(Ti) probe based on dual-parameter sensing technology exhibited excellent potential for selectively detecting 2,4-DNP in water environments, thereby offering significant prospects for its application in water quality assessment.

A SARS-CoV-2 Mpro fluorescent sensor for exploring pharmacodynamic substances from traditional Chinese medicine.

The main protease of SARS-CoV-2 (SARS-CoV-2 Mpro) plays a critical role in the replication and life cycle of the virus. Currently, how to screen SARS-CoV-2 Mpro inhibitors from complex traditional Chinese medicine (TCM) is the bottleneck for exploring the pharmacodynamic substances of TCM against SARS-CoV-2. In this study, a simple, cost-effective, rapid, and selective fluorescent sensor (TPE-S-TLG sensor) was designed with an AIE (aggregation-induced emission) probe (TPE-Ph-In) and the SARS-CoV-2 Mpro substrate (S-TLG). The TPE-S-TLG sensor was characterized using UV-Vis absorption spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), zeta potential, and Fourier transform infrared (FTIR) spectroscopy techniques. The limit of detection of this method to detect SARS-CoV-2 Mpro was measured to be 5 ng mL-1. Furthermore, the TPE-S-TLG sensor was also successfully applied to screen Mpro inhibitors from Xuebijing injection using the separation and collection of the HPLC-fully automatic partial fraction collector (HPLC-FC). Six active compounds, including protocatechualdehyde, chlorogenic acid, hydroxysafflower yellow A, caffeic acid, isoquercetin, and pentagalloylglucose, were identified using UHPLC-Q-TOF/MS that could achieve 90% of the Mpro inhibition rate for the Xuebijing injection. Accordingly, the strategy can be broadly applied in the detection of disease-related proteases as well as screening active substances from TCM.

The dual nature of biomimetic melanin.

Melanin-inspired nanomaterials offer unique photophysical, electronic and radical scavenging properties that are widely explored for health and environmental preservation, or energy conversion and storage. The incorporation of functional melanin building blocks in more complex nanostructures or surfaces is typically achieved via a bottom-up approach starting from a molecular precursor, in most cases dopamine. Here we demonstrate that indeed, the oxidative polymerization of dopamine, for the synthesis of melanin-like polydopamine (PDA), leads to the simultaneous formation of more than one nanosized species with different compositions, morphologies and properties. In particular, a low-density polymeric structure and dense nanoparticles (NP) are simultaneously formed. The two populations could be separated and analyzed in real time using a chromatographic technique free of any stationary phase (flow field fractionation, FFF). The results following the synthesis of melanin-like PDA showed that the NP are formed only during the first 6 hours as a result of a supramolecular self-assembly-driven polymerization, while the formation of the polymer continues for about 36 hours. The two populations were also separated and characterized using TEM, UV-vis absorption spectroscopy, fluorescence and light scattering spectroscopy, DLS, FTIR, ζ-potential measurements, gel electrophoresis and pH titrations. Interestingly, very different properties between the two populations were observed: in particular the polymer contains a higher number of catechol units (8 mmol g-1 -OH) with respect to the NP (1 mmol g-1 -OH) and presents a much higher antioxidant activity. The attenuation of light by NP is more efficient than that by the polymer especially in the Vis-NIR region. Moreover, while the NP scatter light with an efficiency up to 27% they are not fluorescent, and the polymer does not scatter light but shows an excitation wavelength-dependent fluorescence typical of multi-fluorophoric uncoupled systems.

P-Phenylenediamine-derived carbon nanodots for probing solvent interactions.

Carbon nanodots, the luminescent nanoparticles of carbon with size restriction below 10 nm, have attracted inordinate attention in materials science due to their widespread applications in optoelectronic and biological fields. Low toxicity and facile synthesis pathways render them favourites in the above-mentioned areas in the context of green chemistry. This work presents fine applications of p-phenylenediamine-derived carbon nanodots (PD-CNDs) achieved via a facile one-pot hydrothermal method. Adequate characterization using X-ray diffraction and spectroscopic and microscopic studies confirmed spherical particles with an average particle size of 2.8 nm, functionalised with amino, carboxyl, and hydroxyl groups. The carbon framework was functionalised with pyridinic and pyrrolic nitrogens. Upon 365 nm UV light illumination, an aqueous dispersion of PD-CNDs showed red-orange fluorescence. Detailed spectral analysis using UV-visible absorption and fluorescence spectroscopy identified edge states and surface groups as luminescent centres, with a significant contribution arising from the latter. The investigation conducted using a collection of solvents, categorized into polar and nonpolar, indicated the potential of the system for applications based on its solvatochromic nature. The feature enabled the determination of different polarity parameters of the solvents, as well as dielectric constants of solvents and solvent mixtures, with considerable accuracy. The system was potent for predicting the composition of a given pair of solvents. The service of the system is also extended for moisture sensing in organic solvents within an error percentage < 1. High quantum yield values (0.61) combined with solvent composition-dependent optical features ensure broader applications of the system to probe solvent interactions.

Copper(II) coordination compounds based on bis-hydrazones of 2,6-diacetylpyridine: synthesis, structure, and cytotoxic activity.

By reacting a series of 2,6-diacetylpyridine bis-hydrazones containing pyrimidine (H2L1), benzimidazole (H2L2) and phthalazine (H2L3) heterocyclic fragments with copper(II) chloride and bromide, a variety of pentacoordinated complexes of the composition [Cu(H2L1)X]X, [Cu(HL2)X] and [Cu(HL3)X], where X = Cl-, Br-, are formed. The properties and structure of the compounds were studied by means of NMR, IR, UV-vis, ESR, and X-ray absorption spectroscopy, cyclic voltammetry and X-Ray single crystal diffraction methods. It was shown that complexes of the cationic type [Cu(H2L1)X]X have an asymmetric structure with a distorted square-pyramidal geometry of the coordination unit. The coordination polyhedron of metal chelates [Cu(HL2)X] and [Cu(HL3)X] is an almost ideal square pyramid. Investigations of the cytotoxic activity of the obtained compounds in vitro on human hepatocellular carcinoma (HepG2) and non-tumor human lung fibroblast (MRC-5) cell lines demonstrated that complexes show higher activity compared with the well-known anticancer agent cisplatin. In addition, metal chelates [Cu(H2L1)Cl]Cl, [Cu(HL2)Cl], [Cu(HL2)Br] and [Cu(HL3)Cl] were less toxic to non-tumor cells MRC-5. A study of the binding of complexes to bovine serum albumin (BSA) protein using fluorescence spectroscopy showed that copper complexes are strongly bound to BSA. To study the mechanism of interaction of the complexes with the DNA of cancer cells, molecular dynamics simulation of the compound [Cu(HL3)Cl] was carried out. It was shown that the complex enters into π-stacking interactions predominantly with adenine and thymine bases.

Innovative use of liquid crystalline acids as color developers in leuco dye-based temperature sensors.

Novel temperature sensors with unique optical properties, based on 4-alkylbenzoic acid developers (CnBA, where n is the number of carbon atoms in the alkyl chain ranging from 4 to 6), which exhibit a liquid crystalline phase, and 6'-(diethylamino)-1',2'-benzofluoran (BF) leuco dye are reported. The main aim of this work is to investigate how the molecular packing of CnBA in different phases affects the development of BF. Various techniques were used to study the prepared temperature sensors' phase transitions and thermal stability. The spectroscopic properties of BF : CnBA (1 : 3) were investigated, using temperature-dependent UV-Vis absorption and emission spectroscopy, and the results show that the sensors demonstrate reversible color-changing properties. When the CnBA developers are at room temperature, the materials are pink and emit orange light, while at approximately 105 °C they turn white and emit yellow light. Above that temperature, the sensors return to a pink and orange light emission. Therefore the prepared materials can serve as indicators that inform about not only exceeding a certain temperature threshold but also reaching temperature ranges.

Functionalized carbon nanostructures as temozolomide carriers: Physicochemical and biopharmaceutical characterization

In this study, temozolomide (TMZ), a drug used in the treatment of anaplastic astrocytoma and glioblastoma multiforme, was incorporated in multiwalled carbon nanotubes (MWCNTs) and hybrid carbon nanotubes with graphene (MWCNTs-G) functionalized by polyethylene glycol (PEG). The aim was to evaluate the potential of these nanocarriers for targeted delivery and sustained release of TMZ in brain tumor cells. Oxidized MWCNTs and MWCNTs-G were noncovalently functionalized with PEGs of different molecular weights and subsequently loaded with TMZ following standard procedures. Thorough physicochemical and biopharmaceutical characterization of the TMZ-loaded carbon nanocarriers pointed to high encapsulation efficacy (up to 67%) and drug loading (up to 18% out of 25% theoretical value) and homogeneous particle size distribution, with z-average (160 to 300 nm) and zeta potential (?31 to ?21 mV) of the particles adequate for crossing the blood-brain-tumor-barrier (BBTB) and entering into the tumor cells. Successful functionalization and TMZ loading were confirmed by SEM and TEM images, UV-Vis absorption, infrared and Raman spectroscopy, and TGA analyses. Sustained release of TMZ from the carbon nanocarriers was observed in vitro. The presented findings form a fundamental platform for further investigation of these formulations against different types of glioma cells and in adequate animal models.

Enhanced stability of boron modified NiFe hydroxide for oxygen evolution reaction.

The introduction of non-metal elements including boron has been identified as a significant means to enhance oxygen evolution reaction (OER) performance in NiFe-based catalysts. To understand the catalytic activity and stability, recent attention has widened toward the Fe species as a potential contributor, prompting exploration from various perspectives. Here, boron incorporation in NiFe hydroxide achieves significantly enhanced activity and stability compared to the boron-free NiFe hydroxide. The boron inclusion in NiFe hydroxide is found to show exceptionally improved stability from 12 to 100 hours at a high current density (200 mA cm-2). It facilitates the production and redeposition of OER-active, high-valent Fe species in NiFe hydroxide based on the operando Raman, UV-vis, and X-ray absorption spectroscopy analysis. It is proposed that preserving a homogenous distribution of Fe across the boron-containing catalyst surface enhances OER stability, unlike the bare NiFe hydroxide electrocatalyst, which exhibits uneven Fe dissolution, confirmed through elementary mapping analysis. These findings shed light on the potential of anionic regulation to augment the activity of iron, an aspect not previously explored in depth, and thus are expected to aid in designing practical OER electrocatalysts.

Mechanisms of controlled stabilizer-free synthesis of gold nanoparticles in liquid aerosol containing plasma.

The interaction between low-temperature plasma and liquid enables highly reactive solution phase chemistry and fast reaction kinetics. In this work, we demonstrate the rapid synthesis of stabilizer-free, spherical and crystalline gold nanoparticles (AuNP). More than 70% of gold ion complex (AuCl- 4) conversion is achieved within a droplet residence time in the plasma of ∼10 ms. The average size of the AuNPs increases with an increase in the droplet residence time and the particle synthesis showed a power threshold effect suggesting the applicability of the classical nucleation theory. Leveraging UV-vis absorption and emission spectroscopy, and nanoparticle size distributions obtained from TEM measurements, we showed that the AuCl- 4 conversion exceeded by 250 times the maximum faradaic efficiency. We identified important roles of both short-lived reducing species including solvated electrons and possibly vacuum ultraviolet (VUV) photons, and long-lived species, H2O2, in the reduction of AuCl- 4. A quantitative investigation was performed by a 1-D reaction-diffusion model which includes transport, plasma-enabled interfacial reduction of AuCl- 4, classical nucleation, monomer absorption and autocatalytic surface growth enabled by H2O2. The model shows good agreement with the experimental results. The timescale analysis of the simulation revealed that nucleation is enabled by fast reduction of gold ions, and autocatalytic growth mainly determines the particle size and is responsible for the majority of the ion precursor conversion while also explaining the excessively large faradaic efficiency found experimentally.