Spectrophotometric Measurements Research Articles

Surface characterization of bis-amide calix[4]arene doped SWCNT nanocomposite and its application as an electrochemical sensor for the determination of Al3+ ion

This study focuses on the optical, wettability, morphological and sensing properties of the chromogenic bis-amide calix[4]arene-SWCNT nanocomposite thin film. Nanocomposite solution was done by mixing single-walled carbon nanotubes with 5,17-bis(phenylazo)-26,28 bis{[(ethoxycarbonyl)methylcarbamoyl] methoxy}-25,27-di(ethoxycarbonylmethoxy)-calix[4]arene in chlorobenzene. The possible interactions between bis-amide calixarene and SWCNT that may be responsible for enhancement in certain properties of the nanocomposite were highlighted. Firstly, the surface of the modified electrode was characterized by using UV–visible spectrophotometer and contact angle measurement (CAM). The effect of the SWCNT loading in the solution and the heating process on the film properties plays a crucial role in the optical and wettability properties of the CNTs based films. Then, morphological study was examined before and after CNT incorporation by using scanning electron microscopy. Finally, the sensing properties of bis-amide calix[4]arene-SWCNT thin film coated gold electrode were investigated using electrochemical impedance spectroscopy (EIS) toward the detection of Al3+ ion.

Color Stability of Microhybrid Composite Resins Depending on the Immersion Medium.

The aim of this study was to assess the color stability of two microhybrid composite resins after immersion in different coloring solutions for 4 weeks. Sixty disc-shaped samples (2 mm in thickness and 10 mm in diameter) were prepared according to ISO standard 4049. Two composite resins were used: Filtek Z350 XT (3M ESPE) and Harvard Restore (Harvard Dental International GmbH). After initial color measurements, five samples of each resin were immersed in artificial saliva, Turkish coffee, lemonade, black tea, Coca-Cola 0%, and green tea for 4 weeks. The spectrophotometric measurements were carried out after 24 hours of immersion in the various solutions and then weekly, using a VITA Easyshade Advance 4.0 spectrophotometer (CIE L*a*b* system). Statistical analysis was carried out with SPSS 25.0 software. The two composite resins tested revealed discoloration after immersion in all the drinks at a variable immersion period showing different color behaviors. The one-way analysis of variance showed a significant difference in the values of brightness (L), in chromaticity from green to red (a), in chromaticity from blue to yellow (b), and in the color (ΔE) of the two materials at different time intervals. The greatest color change in all the groups was caused by coffee followed by lemonade and black tea followed by green tea, Coca-Cola 0%, and artificial saliva. The importance of color stability of dental restorations is crucial for dental professionals and patients. Indeed, the quality of a restoration is considered from both a functional and esthetic points of view. The information obtained from this study should prove useful for clinicians to make informed decisions in selecting the best materials for their patients' esthetic restorations. The Harvard Restore showed a better colorimetric behavior compared with the Filtek Z350. Coffee, black tea, and green tea had the most marked effects on the discoloration of composites, especially on Filtek Z350. Coca-Cola 0% showed a similar behavior to artificial saliva.

Comparative analysis using UPLC and UV methods for concurrent quantification of therapeutic drugs for overactive bladder: Effective approach in green and white chemistry

This study evaluates the analysis of Mirabegron (MIR) and Solifenacin (SOL), widely used for treating overactive bladder (OAB), using two direct UPLC and spectrophotometric techniques. These methods were developed to be environmentally friendly, utilizing AGREE, GAPI, AGREEprep, ComplexGAPI, AMGS, ESA, HPLC-EAT, AMVI, and BAGI tools. Spectrophotometry, including the first derivative ratio spectrophotometric method (1DD), measures SOL and MIR at 224.8 nm and 258.6 nm, respectively. A method known as the extended ratio subtraction method (EXRSM) is used to resolve the overlap between the SOL and MIR. In this method, the binary mixture spectrum is divided by the divisor. A constant value is subtracted from the plateau region. MIR and SOL at λmax of 248.9 nm and 229.8 nm have a zero-order (D0) after being multiplied by a divisor. The MCR technique has successfully addressed the issue of spectral overlaps for SOL and MIR at 218.5 and 249.7 nm wavelengths. The second method, UPLC densitometry, separates pharmaceuticals using a UPLC C18 1.7 µm (2.1 × 50 mm) column with Ethanol: phosphate buffer pH 4.2 (35:65 v/v) mobile phase at a 0.6 ml/min flow rate, detecting drugs at 210 nm. Calibration curves for both techniques showed a correlation coefficient greater than 0.999 for SOL and MIR in the 1–65 µg mL−1, 1–60 µg mL−1, and 5–25 µg mL−1, respectively. The methods were validated according to International Conference on Harmonization (ICH) principles. These techniques offer cost-effective, eco-friendly alternatives to traditional methods, promoting sustainability in analytical chemistry.

Ensuring the stability of spectrophotometric measurement results during analysis of mixtures composition

Spectrophotometric methods for studying the composition of mixtures are considered. The need to increase the stability and accuracy of the results of spectrophotometric measurements when analyzing substances with low absorption coefficients or a low concentration of the determined substance is shown. A spectrophotometric complex with a thermostated cell is described, which enables to study gaseous and liquid mixtures. Results of study at this complex of absorption spectra of isomers of liquid xylene and their mixtures are given. Methods of increasing the stability of spectrophotometric measurement results, hardware and data processing methods necessary for this are considered. It has been shown that thermostating of not only vaporous, but also liquid samples is one of the necessary conditions for ensuring the stability of measurement results. The procedure for performing experiments and processing the results of spectrophotometric measurements is presented. A differential method has been developed to reduce the impact of spectrophotometer signal instabilities on the accuracy of determining the composition of mixtures. The method consists in using as input data for multiple linear regression not the absorption spectrum, but its wavelength derivative. An analysis of the composition of mixtures of two xylene isomers showed that the use of this method can reduce RMS of determining the composition of mixtures by about 1.6 times. It is noted that additional filtering (smoothing) of the measured absorption spectrum derivative may be required to reduce errors in determining the composition of mixtures. The developed method of reducing the influence of the spectrophotometer signal instabilities on the results of the mixture composition analysis is of the greatest interest for the analysis of substances with low absorption coefficients or in the case of low concentrations of the studied substances and can be used to solve environmental monitoring problems, for example, when determining hydrocarbon contaminants in the atmosphere.

A Spectrophotometric Method to Determine Minimal Erythema Dose for Ultraviolet Radiation in Human Skin.

Background/Objectives: Ultraviolet radiation (UVR) induces oxidative stress in the skin by generating reactive oxygen species (ROS), which can lead to inflammatory conditions including erythema (a sign of sunburn). This clinical study aims to develop an instrumental evaluation method to determine the minimal erythema dose (MED) for UVR. Methods: Fourteen human subjects aged 27 to 57 years (48.93 ± 8.54) participated in this study. Six subsites were designated on the test skin site of each subject and irradiated with UVR at different doses. The examiner visually assessed erythema, determining the 'visual MED'. Additionally, the a* value (a chrominance parameter presenting greenness to redness) was measured using a spectrophotometer as an indicator of erythema. The a* values of the UVR-irradiated subsites were compared to the non-irradiated control value, and the differences were referred to as Δa*. The Δa* value of the subsites irradiated with UVR at the 'visual MED' was referred to as the Δa*VMED for each subject. The mean of the Δa*VMED values of all subjects was chosen as a criterion value for the 'instrumental MED'. The 'instrumental MED' was defined as the lowest dose of UVR that causes an Δa* value equivalent to the criterion value. The 'visual MED' and 'instrumental MED' values of all subjects were subjected to correlation analysis. Results: The mean of the Δa*VMED values of all subjects was 1.88 ± 0.8. The means of the 'visual MED' and 'instrumental MED' values (in J m-2 unit) of all subjects were 300.14 ± 84.16 and 303.29 ± 77.99, respectively. In Pearson correlation analysis, the 'instrumental MED' and 'visual MED' values had a very strong positive correlation with each other (r = 0.864, p = 0.000). Conclusions: This study suggests that the instrumental evaluation method of MED based on the spectrophotometric measurement of the a* values can complement or replace the visual evaluation method and that this method will be useful in monitoring skin tolerance to oxidative stress affected by prooxidant factors and defensive factors.

Physical–chemical characterization of purified phenol red for spectrophotometric pH measurements in riverine, estuarine, and oceanic waters

Physical–chemical characterization of purified phenol red for spectrophotometric pH measurements in riverine, estuarine, and oceanic waters

Development and validation of polymer-based porphyrin-incorporated reference materials for calibration of quantitative light-induced fluorescence device

BackgroundThis study aimed at developing and validating polymer-based reference materials with varying amounts of porphyrin to accurately assess and calibrate quantitative light-induced fluorescence (QLF) device. MethodsReference materials with porphyrin concentrations ranging from 0 to 0.08 wt.% were prepared. The surface properties of the materials were analyzed via gloss and roughness measurements. Color analysis of the specimens was performed on black and white backgrounds with or without filters using a spectrophotometer. This approach revealed the correlations between fluorescence and color. The fluorescence emitted by the specimens was analyzed by measuring ΔR and ΔRmax values using a QLF-D Biluminator™. ResultsThe surface gloss and roughness of the reference materials were not affected by the porphyrin content (p > 0.005). Spectrophotometric measurements revealed significant color differences among most specimen groups depending on the background color and the presence of a filter. QLF-D imaging revealed significant differences in fluorescence (ΔR and ΔRmax) among all specimen groups regardless of the background. The fluorescence values observed on the black backgrounds were higher than those observed on the white backgrounds (p < 0.05). ConclusionsThe developed polymer-based porphyrin-incorporated materials serve as reliable reference standards for accurate assessment and calibration of QLF devices. This study demonstrates the importance of background conditions in fluorescence detection and highlights the potential of these materials as standards for QLF device calibration.

A silver lining in MRSA treatment: The synergistic action of poloxamer-stabilized silver nanoparticles and methicillin against antimicrobial resistance

BackgroundIncreasing antibiotic resistance in bacterial infections, including drug-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA), necessitates innovative therapeutic solutions. Silver nanoparticles are promising for combating infections, but toxicity concerns emphasize the importance of factors like dosage, size, shape, and surface chemistry. Hence, exploring poloxamer as a stabilizing agent to reduce its toxicity and enhance the antibacterial effect on MRSA is investigated. MethodsSilver nanoparticles stabilized with poloxamer (AgNPs@Pol) were synthesized through the chemical reduction method and characterized using UV–visible spectrophotometer, HR-TEM, DLS, and Zeta potential measurements. Subsequently, the antibacterial activity of AgNPs@Pol alone and in combination with methicillin against MRSA and methicillin-susceptible S. aureus (MSSA) was evaluated using the broth microdilution method. ResultsAgNPs@Pol showed significant efficacy against MRSA and MSSA, achieving a 100 % reduction in colony-forming units (CFU) at 9.7 μg/ml. The minimum inhibitory concentration (MIC) against MRSA and MSSA was 8.6 μg/ml and 4.3 μg/ml, respectively. A synergistic effect was observed when AgNPs@Pol was combined with methicillin. Treatment with AgNPs@Pol increased reactive oxygen species (ROS) production in both strains, contributing to its antibacterial activity. Real-time qPCR analysis indicated the downregulation of genes involved in antimicrobial resistance and cell adhesion in both strains. Further, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated low cytotoxicity for AgNPs@Pol against MCF-7, MG-63, and NIH-3T3 cell lines. ConclusionThe developed AgNPs@Pol demonstrated extensive colloidal stability, potent antibacterial activity and synergistic effect with methicillin against MRSA and MSSA. Further studies in primary cells and in vivo models may validate its potential for clinical applications.

Impact of Effectors on the Catalytic Activity of Galactonolactone Oxidase from &lt;i&gt;Trypanosoma cruzi&lt;/i&gt;

The influence of the structure of the effectors, 1,4-benzoquinone, coenzymes Q and their structural analogues, on the activity of galactonolactone oxidase from Trypanosoma cruzi (TcGAL) and the homologous enzyme L-galactono-1,4-lactone dehydrogenase from Arabidopsis thaliana (AtGALDH) was studied. Using two forms of AtGALDH, natural (dehydrogenase) and mutant (exhibiting oxidase activity), the role of 1,4-benzoquinone and its analogs as electron acceptors of AtGALDH and TcGAL was revealed. It has been established that compounds containing methoxy groups are more effective electron acceptors for TcGAL (coenzyme Q0, 2,6-dimethoxy-1,4-benzoquinone) compared to compounds without OCH3 groups (2,5-dihydroxy-1,4-benzoquinone). Using 2,6-dimethoxy-1,4-benzoquinone as an electron acceptor, an approach to the spectrophotometric measurement of TcGAL activity by changes in the absorption of the electron acceptor in the absence of additional components (a dye that becomes colorless when interacting with the reaction product, ascorbate) is proposed. The results obtained allow for a more targeted search for TcGAL inhibitors, which can be considered as the basis for the development of selective drugs against Chagas disease caused by T. cruzi.

Comprehensive analysis of antioxidant and antibacterial activities of water and methanol extracts of Hibiscus flower

This study provides a comprehensive investigation into the antioxidant and antibacterial properties of Hibiscus flower extracts, highlighting their potential for future applications in functional foods. The research addressed key challenges by employing a multi-faceted approach, including four distinct methods for evaluating antioxidant potential: DPPH and FRAP assays, reducing power, and chelating ability of Fe ions. Total phenolic content was quantified using the Folin–Ciocalteu method, while tannins and flavonoids were assessed via vanillin–HCl and aluminum chloride assays. Additional analyses included spectrophotometric measurement of total flavonols and anthocyanins. Antibacterial activity was determined using a modified agar disk diffusion method, with results indicating significant inhibition of Salmonella typhimurium and Staphylococcus aureus by both aqueous and methanolic extracts. Colorimetric analysis revealed a reduction in chroma and hue angles, while FTIR spectroscopy identified key functional groups, such as suberin, lipids, and polysaccharides. Notably, the antioxidant efficacy varied depending on the solvent used, with aqueous extracts showing higher total phenolic content (4325.12 mg GAE/100 g) compared to methanolic extracts (3487.05 mg GAE/100 g). The study concludes that Hibiscus flower extracts, rich in antioxidants like tannins and anthocyanins, possess significant potential for use as natural preservatives and colorants in food products, supporting their role in developing novel functional foods.

Development of Titanium Dioxide Coating for Self-Cleaning Photovoltaic Panels

Amid escalating global energy demands and environmental concerns, the transition to renewable sources like solar power is imperative. Despite the advancements in photovoltaic (PV) technology promising increased efficiency, soiling on PV panels—composed of dust, bird droppings, and contaminants—poses a significant challenge, obstructing sunlight and reducing energy conversion efficiency. Building upon existing research on titanium dioxide (TiO2) nanoparticle coatings, our study investigates their super-hydrophilic and anti-soiling characteristics to enhance self-cleaning capabilities in solar applications. Furthermore, our research investigates the application of (3-aminopropyl)trimethoxy silane as an interlayer to reinforce the adherence of the TiO2 coating to PV panel glass, thereby enhancing its durability. Preliminary results highlight the coating’s exceptional super-hydrophilic properties, with water contact angle measurements less than 10°, indicative of TiO2’s strong water affinity. Spectrophotometer measurements show that the developed coating maintains high optical transmittances for the wavelength range from 350 to 800 nm, which is the most crucial factor for energy conversion in solar panels. Our contributions aim to advance solar energy technologies and support the shift towards more sustainable energy solutions, highlighting the role of innovative materials science in addressing solar power’s operational challenges.

Glucose-6-phosphate dehydrogenase deficiency detection using fluorocytometric assay: Evaluation after 1 year of clinical implementation.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzymopathy that affects red blood cells (RBCs) and renders them susceptible to oxidative stress. G6PD deficiency can cause hemolytic anemia, especially after exposure to certain drugs or infections. The diagnosis of G6PD deficiency is usually based on spectrophotometric measurement of enzyme activity, but this method has limitations in heterozygous females and in patients with other hematological disorders. In this study, we evaluated the use of flow cytometry as an alternative method for detecting G6PD deficiency in 514 samples (265 females and 249 males) from a clinical laboratory. We compared the results of flow cytometry with those of spectrophotometry and molecular analysis, and assessed the performance of flow cytometry in different subgroups of patients. We found that flow cytometry was able to identify G6PD deficiency in most cases, with high sensitivity and specificity. Flow cytometry also allowed the quantification of the percentage of G6PD-deficient RBCs, which varied among heterozygous females due to X-chromosome inactivation. Moreover, flow cytometry detected several cases of G6PD deficiency that were missed by spectrophotometry, especially in heterozygous females with normal or subnormal enzyme activity. However, flow cytometry also showed some false negative results, mainly in patients with sickle cell disease. Therefore, flow cytometry is a reliable and efficient tool for screening G6PD deficiency, but some precautions should be taken in interpreting the results in patients with other hematological conditions.

Soluble adenylyl cyclase is an acid-base sensor in rainbow trout red blood cells that regulates intracellular pH and haemoglobin-oxygen binding.

To identify the physiological role of the acid-base sensing enzyme, soluble adenylyl cyclase (sAC), in red blood cells (RBC) of the model teleost fish, rainbow trout. We used: (i) super-resolution microscopy to determine the subcellular location of sAC protein; (ii) live-cell imaging of RBC intracellular pH (pHi) with specific sAC inhibition (KH7 or LRE1) to determine its role in cellular acid-base regulation; (iii) spectrophotometric measurements of haemoglobin-oxygen (Hb-O2) binding in steady-state conditions; and (iv) during simulated arterial-venous transit, to determine the role of sAC in systemic O2 transport. Distinct pools of sAC protein were detected in the RBC cytoplasm, at the plasma membrane and within the nucleus. Inhibition of sAC decreased the setpoint for RBC pHi regulation by ~0.25 pH units compared to controls, and slowed the rates of RBC pHi recovery after an acid-base disturbance. RBC pHi recovery was entirely through the anion exchanger (AE) that was in part regulated by HCO3 --dependent sAC signaling. Inhibition of sAC decreased Hb-O2 affinity during a respiratory acidosis compared to controls and reduced the cooperativity of O2 binding. During invitro simulations of arterial-venous transit, sAC inhibition decreased the amount of O2 that is unloaded by ~11%. sAC represents a novel acid-base sensor in the RBCs of rainbow trout, where it participates in the modulation of RBC pHi and blood O2 transport though the regulation of AE activity. If substantiated in other species, these findings may have broad implications for our understanding of cardiovascular physiology in vertebrates.

Novel multi-function setup comprising ultra-bright uniform source for spectral and radiometric calibrations of digital imaging sensors and multiple spectrometric applications

Abstract A new setup is being developed for calibrating CCD/CMOS sensors and cameras, and measuring spectrophotometric quantities in both point-wise and imaging modes. The setup includes a laser-driven light source (LDLS), double-grating monochromator, and an integrating sphere with specific design for two-dimensional (2D) spectrophotometric measurements of complex samples and spectral responsivity calibration of digital imaging sensors and cameras in the visible to near infrared (VIS-NIR) region. The setup can cover a spectral range from 250 nm to 2000 nm with relatively high radiance. The study presents optimization and validation work in the visible through NIR spectral range, up to 1000 nm. Preliminary experiments suggest improved accuracy and lower uncertainties for better metrological performance and sophisticated applications. The developed instrument promises a variety of novel applications while suppressing systematic errors and inaccuracies. The presented measurements results include the validation of 2D spectral reflectance/transmittance measurements in the 360-1000 nm spectral region using selected homogenous standards. Additionally provided are the findings of demonstration measurements for 2D spectral transmittance and the CCD camera’s spectral responsivity within the same spectral range.

The Interaction of Nickel (II) Ion with Ethylene Diamine (en) Chelate Using Ethaline (Ionic Liquid) as a Solvent

For this experiment, this is the first time using 1 choline chloride (ChCl): 2 ethylene glycol (EG)based liquid (ethaline) to study the interaction between Ni (II) with ethylene diamine. Two of the optical methods for analyzing spectrophotometric measurements (continuous variations and molar ratio methods) have been utilized for determination of, the stoichiometry and whenever possible, the stability constants of the chelates formed. Job`s method was necessary to determine whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the maximum wavelength and for meaningful conclusions the wavelengths were carefully chosen. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also investigated. The stability constants, K1, K2and K3 for the nickel (II) chelates were calculated by both optical methods, though reliable, and are comparable to literature values.

Preparation of Nano-Sized Eucalyptus Leaves Extract and its Application on Cotton as Natural Dyes and Antibacterial Agents

Nano-emulsions of Eucalyptus globulus leaves extract in 96% ethanol and 96% methanol were successfully prepared using the method of homogenization at various speeds of 13,000 rpm, 15,000 rpm and 17,000 rpm, with the addition of non-ionic surfactant to prevent agglomeration. A phytochemical analysis showed the presence of tannin, phenol and flavonoids. The size of the resulting nano-emulsions was measured using a particle size analyser (PSA) prior to the dyeing of cotton fabrics using the two-dips-two-nips method. Antibacterial tests were carried out on the extracts and dyed fabrics. The results showed that nano-sized particles (&lt; 100 nm) were obtained from all extracts in both solvents used at all speeds. All dyed fabrics showed good levelness in a pale-brown colour with K/S values &lt; 1 for all samples under spectrophotometric measurement. The colour fastness of the dyed fabrics to washing and rubbing were good to very good, with grey scale values ranging between 4/5–5. Antibacterial tests in Staphylococcus aureus bacterium showed that the eucalyptus leaves extract solution exhibited antibacterial ability, as evidenced by the formation of clear zones around the wells. Much better antibacterial activity was demonstrated by the dyed fabrics. Changing the particle size to nano increased the effectiveness of the antibacterial activity of the Eucalyptus globulus. Results showed that the nano-sized eucalyptus leaves extract demonstrated a more significant antibacterial activity than dyeability.

Wide spectral range optical characterization of niobium pentoxide ([formula omitted]) films by universal dispersion model

In this work, the optical properties of niobium pentoxide (Nb2O5) films were extensively studied across a wide spectral range using heterogeneous data-processing methods, combining ellipsometric and spectrophotometric measurements for five samples with thicknesses between 20 and 250 nm. This study primarily determined the optical constants of Nb2O5 from the far infrared to the vacuum ultraviolet, presenting these constants as dispersion parameters using the universal dispersion model to describe valence electron excitations in ultraviolet region as well as phonon vibrations in infrared region. These comprehensive and reliable data across such a broad spectral range are unprecedented. Secondly, presented optical characterization proofs that Nb2O5 films can be grown without defects such as surface roughness, porosity, or inhomogeneity. This fact, together with its high refractive index, makes Nb2O5 a promising material for optical applications.

Green synthesis of silver nanoparticles using carob leaf extract: Characterization and analysis of toxic effects in model organism Galleria mellonella L. (The greater wax moth).

Silver nanoparticles (Ag NPs) have been used in many studies due to their inhibitory properties on microorganisms such as bacteria and viruses. In recent years, due to global problems such as environmental pollution, the green synthesis (biosynthesis) method is frequently preferred because it is simple and low cost and does not require the use of toxic substances. The aim of this study is to synthesize silver nanoparticles (Ag NPs) from Ceratonia siliqua L. leaves and investigate their antioxidant and immunotoxic properties using Galleria mellonella last instar larvae. The UV spectrophotometer, TEM, XRD and FTIR measurements were used to characterize the Ag NPs. In this study, it was determined that the effects on antioxidant enzyme activities (SOD, CAT, GPx, GST), acetylcholinesterase (AChE) and total hemocyte count (THC) as well as phenoloxidase activity determine their effect on antioxidant defence and the immune system in model organism G. mellonella larvae. We observed that green synthesized Ag NPs accumulate in the midgut of the larvae and led to the increasing of CAT and SOD activities. GST and AChE activities were increased in the fat body of the larvae; otherwise, it was decreased in the midgut. Moreover, increases were found in THC and phenoloxidase activity. Consequently, green synthesized silver nanoparticles led to oxidative stress and immunotoxic effects on G. mellonella larvae.

In Vitro Study of Cyano-Phycocyanin Release from Hydrogels and Ex Vivo Study of Skin Penetration.

This study explored the most suitable materials for incorporating cyano-phycocyanin (C-PC) into hydrogels, focusing on maintaining the C-PC's long-term structural integrity and stabilityNext, the release of C-PC from the hydrogels and its skin penetration were investigated. A series of 1% (w/w) C-PC hydrogels was prepared using various gelling agents and preservatives. Spectrophotometric measurements compared the amount of C-PC in the hydrogels to the initially added amount. After selecting the most suitable gelling agent and preservative, two C-PC hydrogels, with and without propylene glycol (PG) (Sigma-Aldrich, St. Louis, MO, USA), were produced for further testing. In vitro release studies utilized modified Franz-type diffusion cells, while ex vivo skin-permeation studies employed Bronaugh-type cells and human skin. Confocal laser scanning microscopy analyzed C-PC accumulation in the skin. The findings demonstrated that sodium alginate (Sigma-Aldrich, St. Louis, MO, USA), hydroxyethyl cellulose (HEC) (Sigma-Aldrich, St. Louis, MO, USA), and SoligelTM (Givaudan, Vernier, Switzerland) are effective biopolymers for formulating hydrogels while maintaining C-PC stability. After 6 h, C-PC release from the hydrogel containing PG was approximately 10% or 728.07 (±19.35) μg/cm2, significantly higher than the nearly 7% or 531.44 (±26.81) μg/cm2 release from the hydrogel without PG (p < 0.05). The ex vivo qualitative skin-permeation study indicated that PG enhances C-PC penetration into the outermost skin layer. PG's ability to enhance the release of C-PC from the hydrogel, coupled with its capacity to modify the skin barrier ex vivo, facilitates the penetration of C-PC into the stratum corneum.

On analysis of structural and optical absorption characterization of Bi35Sb5Se60 nanostructured thin films for photosensing application

In this extensive study, the primary focus is directed towards the intricate exploration of the optical absorption characteristics inherent in nanostructured Bi35Sb5Se60 thin films, prepared by thermal evaporation under a vacuum of 10−5 Torr, ensuring high purity and uniformity for optoelectronic applications. With a particular emphasis on their prospective application in photosensing devices. The research employs a comprehensive approach, integrating various spectrophotometric measurements that encompass both transmission and reflection analyses. The meticulous examination of the absorption edge characteristics reveals a direct energy gap of 1.82 eV, providing a foundational understanding of the material's electronic structure. The determination of the dispersion energy at 6.35 eV and the oscillator energy at 2.96 eV further enriches the understanding of the material's optical behavior, shedding light on its capacity to interact with incident light. A noteworthy highlight emerges with the identification of high photosensitivity exhibited by the heterojunction, particularly under lower reverse bias conditions, underscoring its potential utility in photosensing applications. The PL spectra reveal a highly broadened defect emission band with peaks at 475 nm, 490 nm, and 540 nm, providing insights into the recombination processes within the material. The identification of emission peaks related to the conduction band edge and acceptor levels further enhances the comprehension of the material's optical and electronic characteristics. underscores the potential of these nanostructured thin films for efficient photosensing devices. The findings presented in this research not only advance the understanding of the material's properties but also lay a robust foundation for further research and development in the design and optimization of photoresponsive devices within the realm of optoelectronic technologies.