Maximum Absorption Peak Research Articles

Orthogonal centre ring field optimization triple-band metamaterial absorber with sensing application

This paper provides a metamaterial for microwave absorbers relying on asymmetric square split rings with a partial E shape in the centre-based resonator. The wideband frequency range shows its sensing capabilities in identifying various oil samples. The optimized MTM unit cell has electrical dimensions of 0.122λο × 0.122λο, where is λο the predicted wavelength at 3.64 GHz resonance frequency, for a total size of 10 × 10 mm2. The FR-4 dielectric substrate, 1.6 mm in thickness, produces the unit cell. The MTM has a maximum absorption peak of 91.46 % at 3.64 GHz, 99.72 % at 5.99 GHz, 96.89 % at 7.47 GHz, and 98.45 % at 10.01 GHz. This MMA has four absorption peaks, making it suitable for use in the triple band (S, C, and X). The centre split gaps and partial E shapes increase unit cell absorption, and the defective CSRR back layer structure improves the transmission coefficient. High absorption is influenced by the central split gaps and an appropriate electric field and magnetic field optimized in the centre ring when the structure is in an Orthogonal orientation. The research used a frequency domain solver operating between 2 and 12 GHz. The scattering characteristics (coefficient of transmission) of the relevant unit cell's equivalent circuit were confirmed using ADS software and the CST result. At frequencies between 3 and 5 GHz, the proposed asymmetric unit cell functions as a double negative (DNG) metamaterial absorber due to its negative permeability and permittivity. Since oil samples have different dielectric constants, the resonance frequency and Q factor are likewise different. Here, we receive a spectrum of frequencies that can be adjusted for use in sensing. The data showed that the suggested sensor is sensitive enough to pick up a variety of oils. The proposed sensor is useful for various applications, from liquid detection to microfluidic sensing and beyond, due to its cheap cost, high sensitivity, high-quality factor, and high electromagnetic radiation (EMR).

Antibody-labelled gold nanoparticles synthesized by laser ablation to detect SARS-CoV-2 antigen spike.

Rapid detection test via lateral flow immunoassay (LFIA) is employed as an alternate method to detect Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Gold nanoparticles (AuNPs), a vital component of LFIA, can be synthesized by laser ablation technique. This intense laser radiation may result in monodisperse gold nanoclusters, which are impurity-free and demonstrate innovative biocompatible surface chemistry. In this current research, laser-ablated AuNPs are produced and coupled with an anti-spike SARS-CoV-2 monoclonal antibody (mAb) generated in our prior study. The AuNPs from 30,000 shots of laser ablation exhibited a robust red color with a maximum absorbance peak at 520 nm. The performance of AuNPs-mAb conjugates as a signal reporter was then evaluated in half-stick LFIA. The size distribution of AuNPs shows a relatively monodisperse and unimodal distribution with average particle diameters of 44.77 nm and a surface potential of -38.5 mV. The purified anti-spike mAb SARS-CoV-2 yielded two protein bands, representing the mAb heavy chain at 55 kDa and its light chain at 25 kDa. The immobilization of anti-spike mAb onto the surface of AuNPs revealed that 25 g/ml of mAb at phosphate buffer pH 9 was required to stabilize the AuNPs. The functional test of this conjugate was performed using dipstick LFIA, and the result shows that the AuNPs-mAb conjugates could successfully detect commercial spike antigen of SARS-CoV-2 at 10 ng level. In this study, laser-ablated AuNPs were functionalized with anti-spike mAb SARS-CoV-2 and successfully used as a signal reporter in half-stick LFIA for detecting antigen spike SARS-CoV-2.

Small-Molecule Phototheranostic Agent with Extended π-Conjugation for Efficient NIR-II Photoacoustic-Imaging-Guided Photothermal Therapy.

Photoacoustic imaging (PAI) and photothermal therapy (PTT) conducted over the near-infrared-II (NIR-II) window offer the benefits of noninvasiveness and deep tissue penetration. This necessitates the development of highly effective therapeutic agents with NIR-II photoresponsivity. Currently, the predominant organic diagnostic agents used in NIR-II PAI-guided PTT are conjugated polymeric materials. However, they exhibit a low in vivo clearance rate and long-term biotoxicity, limiting their clinical translation. In this study, an organic small molecule (CY-1234) with NIR-II absorption and nanoencapsulation (CY-1234 nanoparticles (NPs)) for PAI-guided PTT is reported. Extended π-conjugation is achieved in the molecule by introducing donor-acceptor units at both ends of the molecule. Consequently, CY-1234 exhibits a maximum absorption peak at 1234nm in tetrahydrofuran. Nanoaggregates of CY-1234 are synthesized via F-127 encapsulation. They exhibit an excellent photothermal conversion efficiency of 76.01% upon NIR-II light irradiation. After intravenous injection of CY-1234 NPs into tumor-bearing mice, strong PA signals and excellent tumor ablation are observed under 1064 nm laser irradiation. This preliminary study can pave the way for the development of small-molecule organic nanoformulations for future clinical applications.

The Antibacterial Activity of Biosynthesized Silver Nanoparticles from Tribulus terrestris Against Pseudomonas aeruginosa

The current study’s goal is to employ Tribulus terrestris aqueous floral extracts to synthesize silver nanoparticles (AgNPs) and test their antibacterial efficacy against Pseudomonas aeruginosa (P. aeruginosa) isolated from otitis externa in dogs. Biological nanoparticle synthesis is gaining popularity over chemical and physical processes due to its cost-efficiency and environmental friendliness. Silver nanoparticles were made by mixing Tribulus terrestris plant extract with 1 mM silver nitrate (AgNO3) solution (AgNPs). UV-Visible spectrophotometry revealed the biosynthetic nanoparticles’ maximum absorbance peak at wave lengths (410nm). The SEM was spherical and homogenous in shape, with a size range of 20 to 25 nm. The XRD indicated that the size of AgNPs was 50.21 nm. EDS was utilized to determine the presence of silver element. The AFM revealed the three-dimensional structure of silver nanoparticles with a diameter of 60.17 nm on average. The Zeta potential of the particle size analyzer was 45 mV. It was observed that as the concentration of AgNPs Increased, so did the size of the inhibition zone; (150μg/ml) exhibited a larger inhibition zone (32mm) than when using concentrations of 100μg/ml, 50μg/ml, and 25μg/ml, respectively. In conclusion, biosynthesized AgNPs generated from Tribulus terrestris demonstrate potent antibacterial activity against Pseudomonas aeruginosa isolated from otitis externa in dogs.

Physico-Chemical Alternatives for Synthesis of Metal Nanoparticles Using Fusarium Chlamydosporum

Abstract Introduction/Objective Background: Synthesizing metal nanoparticles (NPs) by chemical or physical methods is difficult due to energy and time consumption, equipment costs, and chemical toxicity. Chemosynthesis-derived NPs are unstable, limiting their biological applications. Thus, identifying alternative green sources to address these drawbacks is difficult scientifically. The hardest part of green metal nanoparticle synthesis is finding a nontoxic natural product and an eco-friendly solvent. Objectives: Isolation of fungal endophytes from Eucalyptus sideroxylon leaves to synthesize ZnO and Au nanoparticles. Methods/Case Report Materials and methods: We used healthy Eucalyptus sideroxylon plant samples from the desert research center to separate endophytes. All fungi were grown on malt extract broth on a rotary shaker at 28 °C (120 rpm) for 96 hours after isolation. Biomass components were removed by filtration and washing in distilled water. Nanoparticles came from biomass cell filtrate. 0.1 M, 1 mL of Zn SO4, and HAuCl4 were added to 10 mL of fungal filtrate and agitated for 24 hours in the dark at room temperature to make Zn and Au nanoparticles separately. Characterization of nanoparticles shows a green synthesis of ZnONPs and AuNPs. Results (if a Case Study enter NA) Results: Fungal endophytes' filtrates were mixed with 1mM Zn SO4 and HAuCl4 solutions to test their extracellular biosynthesis of ZnO and Au NPs. The fungal filtrate became colorless and violet after mixing with Zn SO4 and HAuCl4. Only FI-03 is from 13 (FI-01 to FI-013). The most potent fungal strain for Zn O NP and Au NP nanoparticle synthesis was Fusarium Chlamydosporum. Pure, mostly spherical ZnO and Au NPs averaged 19.3 and 22.1 nm. UV-Vis absorption: Excitonic absorption peaks of ZnO NPs were between 300 and 400 nm. ZnO NPs' maximum absorption peak was 305 nm, while Au NPs' peak was 520 nm. One absorption peak indicates metallic gold nanoparticles. Au and ZnO NPs aggregate the most due to their hydrophilicity, HD of 34.88 and 15.77 nm, and PdI of 0.77, 1.00, and 0.952. Gold face-centered cubic fcc structure dominates Au NPs' XRD pattern. EDX shows 64.61 and 35.39 percent Zn and O, respectively, in both nanoparticles. The optical absorption band of gold nanocrystallites peaked at 2.2 keV in energy-dispersive X-rays. Conclusion Endophytic fungus biosynthesizes ZnO and Au NPs, which are bioactive compounds for medicine and food without toxic chemicals and are environmentally friendly.

Viability of MDR bacteria against antibacterial biosynthesized ZnO and Au Nanoparticles

Abstract Introduction/Objective: Background Resistant strain diseases are increasing worldwide. Antimicrobials are concerned about pathogen-acquired resistance. Nanotechnology advances enable the creation of novel formulations based on various nanoparticles (NPs) with different sizes and antibacterial characteristics. Methods/Case Report Materials and methods All fungi were isolated and cultivated on malt extract broth. The endophytic fungus was cultured. Zn and Au nanoparticles have been produced by adding 0.1 M, 1 mL of Zn SO4, and HAuCl4 to 10 mL of fungal filtrate. Characterization of nanoparticles by the extracts' UV-visible spectrum shows ZnO NPs and Au NPs' green synthesis. UV-Vis, HR-TEM, XRD patterns, EDX analysis, and a Zeta-sizer characterize NPs' optical properties and morphology. Using 2,3,5-triphenyl tetrazolium chloride, biosynthesized Au and ZnO NPs' MICs against bacteria were determined. The bacterial culture was cultivated until it reached an Mc-Farland standard of 0.5. After that, 10 uL of bacterial suspension was pipetted into 140 uL of nutritional broth with 0.12 to 31.25 ug/mL ZnO and Au NPs. ZnO- and Au-free nutrient broth was used as a control. Wells that didn't turn red was examined for MIC values. Results (if a Case Study enter NA): Results The fungal filtrate's color changed from light yellow to colorless and violet after mixing with ZnSO4 and HAuCl4, respectively, ensuring nanoparticle formation. UV-Vis spectra: ZnO NPs were confirmed by excitonic absorption peaks between 300 and 400 nm; the maximum absorbance peak was 305 nm, while Au NPs' peak was 520 nm. Results showed that Au NPs and ZnO NPs have a hydrodynamic diameter (HD) of 34.88 nm and 15.77 nm, respectively. Our EDX analysis revealed that both nanoparticles have 64.61 and 35.39 % Zn and O stoichiometric mass percent. Energy dispersive X-rays showed a peak optical absorption band at 2.2 keV in gold nanocrystallites. Au NPs and ZnO NPs had MICs of 7.81 and 1.95 ug ml-1 against P. aeruginosa and 3.9 and 0.98 against E. coli, respectively. ZnO NPs' MIC against E. coli and P. aeruginosa is lower than Au NPs'. ZnO NPs increased microbial cell proliferation, and its inhibition was affected by the concentrations, sizes, and forms. Conclusion Our study investigated that the number of pathogens Escherichia coli and Pseudomonas aeruginosa decreases as nanoparticle concentration increases. So, ZnO NPs and Au NPs can inhibit bacterial development and cytoplasmic leak contents at lower concentrations.

Skrining fitokimia dan isolasi senyawa steroid/triterpenoid dari ekstrak n-heksana biji nangka (Artocarpus heterophyllus Lam).

Jackfruit (Artocarpus heterophyllus Lam) is a plant that can grow well in tropical regions such as Indonesia. Jackfruit seeds contain steroid/triterpenoid chemical compounds, including several types of steroids that are useful as ingredients in medicines, such as estrogen, progestin, and cardenolides. The research aims to conduct phytochemical testing and isolate steroid/triterpenoid compounds from jackfruit seeds. This research uses experimental methods, including the compound extraction process using the maceration method and the isolation of active compounds via column chromatography. Identification of pure isolates was carried out using UV spectrophotometry and IR spectrophotometry. The results of phytochemical screening showed the presence of steroid/triterpenoid compounds, glycosides, and alkaloids in the samples. The isolate has a purple color with an RF value of 0.25, and the maximum absorption peak is located at a wavelength of 208.20 nm, indicating the presence of a chromophore group. IR spectrophotometry results show the presence of OH, aliphatic -CH, CH2, CH3, C=O, C-O, and C=C. This research concludes that the isolate obtained belongs to the steroid/triterpenoid compound group.

Asymmetric Fluorene‐Based Fused‐Ring Molecules Acceptors for Fullerene‐Free Organic Solar Cells

Asymmetric fluorene‐based fused‐ring molecules acceptors 2,2′‐((2Z,2′Z)‐(((11,11‐dioctyl‐5,5‐dioxido‐11H‐benzo[b]fluoreno[2,3‐d]thiophene‐3,9‐diyl)bis(3‐octylthiophene‐5,2‐diyl))‐bis(methaneylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile [BTOFIC] and 2,2′‐((2Z,2′Z)‐((5,5′‐(11,11‐dioctyl‐11H‐benzo[b]fluoreno[2,3‐d]thiophene‐3,9‐diyl)bis(3‐octylthiophene‐5,2‐diyl))bis(methanylylidene))‐bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diyl‐idene))dimalononitrile [BTFIC] are synthesized. BTOFIC and BTFIC are easily soluble in common organic solvents. The highest occupied molecular orbital energy levels, the lowest unoccupied molecular orbital energy levels, and the bandgaps (Egs) of BTOFIC and BTFIC are −5.91, −3.87, and 2.04 eV and −5.72, −3.81, and 1.91 eV, respectively. BTOFIC and BTFIC show the maximum absorption peak (λmax) at 548 and 648 nm and a strong shoulder peak at 592 and 576 nm in film, and the optical bandgaps of 1.87 and 1.81 eV, respectively. The organic solar cells (OSCs) fabricated with poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] [PTB7‐Th]:BTOFIC and PTB7‐Th:BTFIC show a power conversion efficiency of 3.31% and 5.35%, respectively. In this research, it is revealed that BTOFIC and BTFIC can be potential asymmetric non‐fullerene acceptors for further development of OSCs.

Solvent Impact on Langmuir and Langmuir–Schaefer Films of Soluble Main‐Chain Poly(fullerene)s Based on C60

Understanding the morphology and electronic properties of poly(fullerene)s is crucial for the development of new organic devices. This work addresses the fabrication and characterization of Langmuir–Schaefer (LS) films of poly(fullerene)s based on C60 with short (HSS8) and long (HSS16) sidechains, solubilized in chloroform or xylene. In addition, density functional theory (DFT) calculations are used to optimize the molecular geometries, determine energies, and investigate the influence of solvent applied. Depending on the organic solvent, floating material isotherms indicate the formation of disordered aggregates in the aqueous subphase. The influence of solvent in LS films is also evidenced by way of atomic force microscopy (AFM), UV‐vis, and cyclic voltammetry (CV) measurements. From DFT calculations, the arms of the poly(fullerene)s start to extend from an initial position of surrounding the fullerene sphere. In AFM measurements, depending on the organic solvent, the roughness significantly reduces, while the homogeneity is much higher. In UV‐vis and CV measurements, the propensity to form aggregates depends mainly on the polarization of the solvent and is directly related to the maximum absorption, oxidation, and reduction peaks. From the optical bandgap energy values, the poly(fullerene)s studied here present high potential for application in organic electronic devices.

Spectrophotometric Determination of Ampicillin Using Chromogenic Reagents (MBTH and PDAC) and their Application in Pharmaceutical Formulations

The present work highlights the spectrophotometric method development and validation for the assay of ampicillin, a broad-spectrum β-lactam antibiotic. Two methods have been proposed by employing popular chromogenic reagents viz 3-methyl 2-benzothiazolinone hydrazone (MBTH) and para dimethyl amino cinnamaldehyde (PDAC). Method A involves the coupling of ampicillin with MBTH in the presence of ferric chloride through the oxidative mechanism, resulting in the formation of green coloured solution with a maximum absorption peak at 620 nm. In method B, the condensation reaction of ampicillin with an acidic solution of PDAC gave a coloured reddish-brown complex, showing a maximum absorption peak at 514nm. Linear calibration curve for MBTH and PDAC has been obtained while obeying Beer’s law in the concentration range of 0.5 -1 and 5-15 μg/ml having a good correlation coefficient of 0.9985 and 0.9974 respectively. The sensitivity of the submitted methods was found to be more than the reported methods. Both methods were successfully applied to a pharmaceutical formulation for quantifying the ampicillin effectively. Therefore, the developed spectrophotometric methods can serve as a good analytical assay procedure for ampicillin to undergo quality control in pharmaceutical setups.

A novel reaction-based ratiometric fluorescent probe with large Stokes shift for the detection of Hg2+ in river sample

Based on Hg2+-promoted desulfurization-hydrolysis of the diphenylphosphinothioate moiety, a novel ratiometric fluorescent probe 1 for Hg2+ using hemicyanine as the fluorophore was designed and synthesized. In sensing of Hg2+, the maximum fluorescence emission and absorption peaks of 1 shifted from 450 nm to 504 nm and from 351 nm to 376 nm, respectively, accompanied by color change from colorless to green under illumination with a 365 nm UV lamp. 1 not only exhibited remarkable change in the ratios of both absorbance (A376 nm/A351 nm) and fluorescence intensity (F504 nm/F450 nm), but also had large Stokes shift, fast response, excellent sensitivity, and high selectivity for Hg2+. Furthermore, 1 was successfully applied for Hg2+ detection in river water sample.

Application of different concentrations of the natural dye potassium norbixinate (annatto) in polyamide 6.6 fabrics

Polyamide fabrics were dyed with concentrations ranging from 4% to 0.25% (o.w.f.) of the natural dye, potassium norbixinate (annatto). The exhaustion, chromatic coordinates, colouristic intensity (K/S), and fastness to washing and rubbing were evaluated. The natural dye was characterised, and its maximum absorption peaks were identified at 452 nm and 482 nm through UV-vis scanning. Its main chemical groups were identified by FTIR-ATR. All dyeings exhibited high exhaustion percentage, with a maximum of 98.4% for 1% dye concentration. The dyed samples displayed visually appealing orange hues, with a maximum K/S value of 6.9. Most of the fastness test results were rated between 5 and 4/5, remaining within the standards established by most textile industries. Potassium norbixinate exhibited a similar tinctorial behaviour to synthetic acid dyes for polyamide, suggesting ionic chemical reaction interaction between dye and polyamide, highlighting the potential use in the textile industry.

Enhancement of graphitic carbon nitride (g‐C3N4) assisted photodegradation of Rhodamine B under visible light

AbstractIn the current work, the g‐C3N4 photocatalyst was produced by thermal polycondensation of melamine. The Characterization techniques XRD, SEM, FTIR, UV‐DRS, PL, and BET were investigated to find out inherent properties. The PL spectra of the g‐C3N4 photocatalyst showed good absorbance in visible regions for faster degradation of Rhodamine B (RhdB). The synthesized g‐C3N4 photocatalyst is employed for decolorization and demineralization of RhdB about 73 % and 80 % in 105 min and 480 min under visible light. Further, the addition of H2O2 and H2SO4 to RhdB solution in the presence of g‐C3N4 showed enhanced results when compared to g‐C3N4 alone. Moreover, it reduces the time for the removal of RhdB. Simultaneously impeding shift of the maximum absorption peak of RhdB represents alteration of the degradation mechanism. Under alike conditions of photodegradation, after the addition of H2O2 and H2SO4 to the dye solution. The removal of RhdB is enhanced to 98 % and 95 % in 40 min, and 60 min for 5 mg/l and 10 mg/l respectively for H2O2. Further, the addition of H2SO4 enhances efficiency up to 87 %, and 95 % in 50 min, and 80 min respectively for 5 mg/l and 10 mg/l. The overall H2O2 addition showed better efficiency and better rate constants.

Torsional deformation adjusts the electronic and optical properties of hydrogenated silicene

The electronic and optical properties of hydrogenated silicene at different torsion angles are investigated using the density functional theory (DFT). It was found that when silicene was hydrogenated, the Si atoms were pulled out of plane due to covalent interactions between the Si and H atoms, increasing their flexural height to 0.731 Å. Torsional deformation decreases the structural stability of hydrogenated silicene and its adsorption energy decreases with increasing twist angle. Under the effect of torsion deformation, the bandgap of hydrogenated silicene increases and then decreases. The bandgap is 2.168[Formula: see text]eV at a torsion angle of 0∘, indicating a wide bandgap semiconductor. Mulliken’s charge population analysis shows that charge transfer occurs between Si–H atoms, with Si atoms losing electrons and becoming positively charged and H atoms gaining electrons and becoming negatively charged. From the analysis of optical properties, the torsional deformation induced the maximum absorption and reflection peaks of all the hydrogenated silicene systems to appear in the ultraviolet region. Compared with the system without torsional deformation, these peaks exhibit varying degrees of red and blue shifts. The above findings provide guidance for the application of silicene in nanooptoelectronic devices.

Sunlight-Mediated Synthesis of Metallic Silver Nanoparticles with Coffee (<i>Robusta/Arabica</i>) Pulp Aqueous Extract for Hg<sup>2+</sup> Ion Detection

On-site and portable detection of heavy metals, especially in water, is critical for public health safety. Mercury is a toxic heavy metal and poses environmental and health hazard concerns causing neurological and behavioral disorders. Metallic nanoparticles possess unique optical properties, which can be used for heavy metal sensing applications. In this study, a colorimetric method for detecting mercury using silver nanoparticles was developed. The reduction of Ag+ to AgNP was initiated using sunlight with coffee pulp aqueous extract as a reducing agent. The UV-Vis spectrum of the as-prepared AgNP solution shows a maximum absorption peak at 433 nm due to the metal’s localized surface plasmon resonance (LSPR). The SEM analysis of the dried sample shows an aggregate of AgNPs with spherical morphology with diameters less than 100 nm. The dynamic light scattering distribution curve shows a bimodal peak with a mean hydrodynamic radius of 12.73 nm and 145 nm, respectively. The large hydrodynamic radius of more than 100 nm may be attributed to the presence of AgNP aggregates in the solution. The synthesized AgNP was shown to selectively detect Hg2+ ions in solution colorimetrically. A linear calibration curve was obtained for the Hg2+ solution between 0.04 mM and 0.2 mM with R2 equal to 0.9934. This proposed method can potentially be used in the analysis of actual water samples.

Fluorescence enhancement induced by supramolecular J-aggregation of pyrene dye containing a flexible rotation group

A pyrene dye bearing a flexibly rotated hydrophobic group (3,4,5-tri(dodecyloxy)benzoyl-) was synthesized and fully characterized. In cooling processes for the dye monomer in CHCl3/CH3OH, the monomer was transformed into the J-aggregates which were characterized to possess a typically nanowired shape. A thermodynamic hysteresis of the molar fraction of the aggregates was observed explicitly between the cooling and heating processes. A pronounced self-absorption was involved in the aggregate solutions of the dye at high concentrations. Clearly, the J-aggregation conferred a few intriguing attributes such as a red-shift of maximum absorption peak, a higher quantum yield of absolute fluorescence and a shorter fluorescence lifetime than the monomer. Collectively, these attributes brought about a phenomenon of aggregation-induced emission enhancement (AIEE). In addition, the HOMO and LUMO energies were calculated by DFT for both the monomeric and aggregated states. Furthermore, the stacking parameters in the J-aggregates were evaluated according to the molecular exciton theory. It can be concluded that the J-aggregation enhanced substantially the emission of the dye. Undoubtedly, the strategy for the development of the AIEE molecules containing a flexible rotation group via J-aggregation as revealed in this work will be very useful in the future design of new organic light-emitting dyes.

Preparation and Characterization of an Oyster Peptide-Zinc Complex and Its Antiproliferative Activity on HepG2 Cells.

It is evident that zinc supplementation is essential for maintaining good health and preventing disease. In this study, a novel oyster peptide-zinc complex with an average molecular weight of 500 Da was prepared from oyster meat and purified using ultrafiltration, ultrasound, a programmed cooling procedure, chelating, and dialysis. The optimal chelating process parameters obtained through a response surface methodology optimization design are a peptide/zinc ratio of 15, pH of 6.53, reaction time of 80 min, and peptide concentration of 0.06 g/mL. Then, the structure of a peptide-zinc complex (named COP2-Zn) was investigated using the UV and infrared spectrums. The results showed that the maximum absorption peak was redshifted from 224.5 nm to 228.3 nm and the main difference of the absorption peaks was 1396.4 cm-1. The cytotoxicity and antiproliferative effects of COP2-Zn were evaluated. The results showed that COP2-Zn had a better antiproliferative effect than the unchelated peptide against HepG2 cells. A DNA flow cytometric analysis showed that COP2-Zn induced S-phase arrest in HepG2 cells in a dose-dependent manner. Additionally, the flow cytometer indicated that COP2-Zn significantly induced HepG2 cell apoptosis.

Effect of β-cyclodextrin on whey protein-epigallocatechin gallate interaction

This study aimed to explore the influence of whey protein–epigallocatechin gallate interaction. Nonreducing cyclic polysaccharide (β-cyclodextrin, i.e., β-CD) was added to epigallocatechin gallate (EGCG) and whey protein (WP) to regulate the interaction between polyphenols and proteins. Based on the transmittance, oxidation resistance, and spectral analysis, we used differential scanning calorimetry, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) to characterize the effects of β-CD on the interaction between polyphenols and proteins. The light transmittance of WP was 74.61%, and the EGCG addition reduced the light transmittance of WP by 2.8%. The maximum absorption peak of WP was around 280 nm. EGCG enhanced the fluorescence intensity of WP, caused the blue shift, and also reduced the fluorescence intensity of WP. In addition, the interaction between WP and EGCG also weakened the antioxidant activity of EGCG. β-CD could improve the light transmission and oxidation resistance of the EGCG-WP hybrid system to a certain extent. The β-CD addition had little effect on the thermal stability of the mixed system. In WP–EGCG and β-CD–WP–EGCG systems, the peak intensity of absorption peaks in each group was different. The EGCG addition reduced the crystallinity of the mixed system by 6.25%, and β-CD alleviated this phenomenon to a certain extent. The formed complex became relatively chaotic by adding WP and EGCG, and the system became tightly connected and ordered with the interaction of 0.03% β-CD with WP–EGCG. This study provided the basis for the interaction between β-CD, WP, and EGCG.

Myofibril degradation and structural changes in myofibrillar proteins of porcine longissimus muscles during frozen storage

The effect of frozen time and the temperature on myofibril degradation and the structure of myofibrillar proteins of porcine longissimus muscles were investigated. With extended frozen time and increased temperature, the muscle fibres became broken; the muscle cells became irregularly arranged; and the fragmentation index value, number of ionic bonds, and number of hydrogen bonds of the samples significantly decreased. Meanwhile, the myofibril fragmentation index value, number of hydrophobic interactions, and number of disulphide bonds significantly increased (P < 0.05). After 12 months of storage, the intensities of I760/I1003, I850/I830, I1450/I1003, and I2945/I1003 in the samples frozen at −8 °C were reduced by 4.36 %, 1.28 %, 1.86 %, and 0.74 %, respectively. A reduction in the maximum absorption peak and a red shift were observed in the ultraviolet spectrum. Therefore, frozen storage resulted in significant damage to the tissue microstructureand caused accelerated protein degradation, and the loss of protein structural integrity.

Development and Validation of UV-Spectrophotometric Method for Estimation of Vinpocetine in Marketed Formulation and Nanoformulation

A quick, accurate, and cost-effective UV spectroscopy method was developed to estimate the Vinpocetine concentration in bulk, tablet dosage formulations and niosomes formulations, using a solvent ratio of (6:4) methanol: water. According to ICH guidelines, the proposed technique was validated and developed. In spite of linearity, precision, accuracy, specificity, LOD, and LOQ, like parameters were validated by using UV/visible spectroscopy technique to analyze a spiked Vinpocetine solution. The wavelength at which the drug's maximum absorbance peak was obtained at 274 nm and the solvents used as methanol: water (6:4 w/v). The ethanol injection technique was used to prepare niosomes to analyze Vinpocetine in UV / visible spectrophotometric method.During the inter and intra-day studies, it was discovered that the developed UV technique was accurate, with % relative standard deviation ranging from 0.27 to 0.46 and 0.26 to 0.46, respectively. Vinpocetine overall recovery percentage was discovered to be between 98.42 to 99.82 %. LOQ and LOD were calculated to estimate the method's sensitivity, and they were observed to be 0.4565 µg/ml and 0.1506 µg/ml, respectively. The estimation of Vinpocetine content in bulk form, marketed formulations and niosomes was achieved using the developed methodology. : A quick, accurate, and economical UV spectrophotometric method has been developed. As a result, the suggested UV spectroscopic technique has been developed to estimate the vinpocetine concentration in bulk, tablet dosage formulations, and niosomes formulations.