UV Absorption Spectra Research Articles

Oxidation of Cathepsin D by Hydroxy Radical: Its Effect on Enzyme Structure and Activity against Myofibrillar Proteins Extracted from Coregonus peled.

In this study, cathepsin D was oxidized in vitro with different concentrations of H2O2, and the activity, structure, and extent of myofibrillar protein degradation by oxidized cathepsin D were evaluated. The sulfhydryl content of cathepsin D decreased to 9.20% after oxidation, while the carbonyl content increased to 100.06%. The β-sheet in the secondary structure altered due to oxidation as well. The changes in the intrinsic fluorescence and UV absorption spectra indicated that oxidation could cause swelling and aggregation of cathepsin D molecules. The structure of cathepsin D could change its activity, and the activity was highest under 1 mM H2O2. Cathepsin D could degrade myofibrillar proteins in different treatment groups, and the degree of degradation is various. Therefore, this study could provide a scientific basis for the mechanism of interaction among hydroxyl radical oxidation, cathepsin D, and MP degradation.

Protein Adsorption, Calcium-Binding Ability, and Biocompatibility of Silver Nanoparticle-Loaded Polyvinyl Alcohol (PVA) Hydrogels Using Bone Marrow-Derived Mesenchymal Stem Cells.

Several approaches have evolved to facilitate the exploration of hydrogel systems in biomedical research. In this sense, poly(vinyl alcohol) (PVA) has been widely used in hydrogel (HG) fabrication for several therapeutic applications. The biological properties of PVA hydrogels (PVA-HGs) are highly dependent on their interaction with protein receptors and extracellular matrix (mainly calcium) deposition, for which there is not enough evidence from existing research yet. Thus, for the first time, the functional properties, like protein and mineral interactions, related to the proliferation of mesenchymal stem cells (MSCs) by silver nanoparticle (AgNP)-loaded PVA hydrogels (AgNPs-PVA-HGs) were investigated in the present study. The UV absorption spectrum and TEM microscopic results showed a maximum absorbance of synthesized AgNPs at 409 nm, with an average particle size of 14.5 ± 2.5 nm, respectively. The functional properties, such as the calcium-binding and the protein adsorption of PVA-HG, were accelerated by incorporating AgNPs; however, the swelling properties of the HGs were reduced by AgNPs, which might be due to the masking of the free functional groups (hydroxyl groups of PVA) by AgNPs. SEM images showed the presence of AgNPs with a more porous structure in the HGs. The proliferative effect of MSCs increased over culture time from day 1 to day 7, and the cell proliferative effect was upregulated by HGs with more pronounced AgNPs-PVA-HG. In addition, both HGs did not produce any significant cytotoxicity in the MSCs. The histological (bright light and H&E staining) and fluorescence microscopic images showed the presence of a cytoskeleton and the fibrillar structure of the MSCs, and the cells adhered more firmly to all HGs. More fibrillar bipolar and dense fibrillar structures were seen in the day 1 and day 7 cultures, respectively. Interestingly, the MSCs cultured on AgNPs-PVA-HG produced extracellular matrix deposition on day 7. Accordingly, the present results proved the biocompatibility of AgNPs-PVA-HG as a suitable system for culturing mammalian stem cells for regenerative tissue applications.

A novel protein extracted from Hemerocallis citrina Borani inhibits hepatocellular carcinoma cell proliferation by regulating mitochondria-dependent apoptosis and aerobic glycolysis.

Hemerocallis citrina Borani is a commonly consumed food in Asia and possesses many biologically active ingredients. In this study, a protein named Hemerocallis citrina Borani protein (HcBP) was purified using ammonium sulfate fractionation and anion exchange chromatography. Protease assays revealed that HcBP has peroxidase activity. Meanwhile, the UV absorption spectrum showed that HcBP contains heme. Notably, HcBP showed significant inhibitory effects on human hepatoma cancer cell proliferation. Mechanism investigations indicated that HcBP treatment resulted in overproduction of reactive oxygen species (ROS) and induced mitochondria-dependent apoptosis in human hepatoma cancer cells. Furthermore, we found HcBP not only downregulated pyruvate kinase M2 (PKM2) activity but also decreased the expression and nuclear levels of PKM2. The inhibition of PKM2 led to the downregulationof GLUT1, LDHA and PDK, and thus caused the suppression of glycolysis. In summary, our results suggested that HcBP has potential anti-hepatocellular carcinoma activity.

Quantitative analysis of two COVID-19 antiviral agents, favipiravir and remdesivir, in spiked human plasma using spectrophotometric methods; greenness evaluation

Favipiravir and remdesivir have been included in the COVID-19 treatment guidelines panel of several countries. The main objective of the current work is to develop the first validated green spectrophotometric methods for the determination of favipiravir and remdesivir in spiked human plasma. The UV absorption spectra of favipiravir and remdesivir have shown some overlap, making simultaneous determination difficult. Due to the considerable overlap, two ratio spectra manipulating spectrophotometric methods, namely, ratio difference and the first derivative of ratio spectra, enabled the determination of favipiravir and remdesivir in their pure forms and spiked plasma. The ratio spectra of favipiravir and remdesivir were derived by dividing the spectra of each drug by the suitable spectrum of another drug as a divisor to get the ratio spectra. Favipiravir was determined by calculating the difference between 222 and 256 nm of the derived ratio spectra, while calculating the difference between 247 and 271 nm of the derived ratio spectra enabled the determination of remdesivir. Moreover, the ratio spectra of every drug were transformed to the first order derivative using ∆λ = 4 and a scaling factor of 100. The first-order derivative amplitude values at 228 and 251.20 nm enabled the determination of favipiravir and remdesivir, respectively. Regarding the pharmacokinetic profile of favipiravir (Cmax 4.43 µg/mL) and remdesivir (Cmax 3027 ng/mL), the proposed methods have been successfully applied to the spectrophotometric determination of favipiravir and remdesivir in plasma matrix. Additionally, the greenness of the described methods was evaluated using three metrics systems: the national environmental method index, the analytical eco-scale, and the analytical greenness metric. The results demonstrated that the described models were in accordance with the environmental characteristics.

Effects of CaCl2 on the rheology, microstructure and protein structures of rapidly salted separated egg yolk

Bivalent or trivalent metal salts can enhance the oil output and sandiness of salted eggs. We added CaCl2 to the salting solution to improve the quality of rapidly salted separated egg yolk and investigated its effect on rheological, microstructure, and protein structure. According to the findings, adding CaCl2 to the salting solution can promote the precipitation of egg yolk water, increase its viscosity, induce protein aggregation, and increase the denaturation temperature of the protein. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that the inner boundary of egg yolk salted with CaCl2 was clearer and that the number and size of salted egg yolk lipoprotein aggregates were larger than those of egg yolk salted without CaCl2. Analysis using Fourier transform infrared spectroscopy (FTIR) demonstrated that CaCl2 caused the interconversion of the secondary-level structure. CaCl2 can have an impact on the microenvironment of amino acid residues, according to the results of 3D fluorescence and UV absorption spectra. Therefore, adding CaCl2 can accelerate the loss of water and change the structure of lipoprotein in egg yolk, which improves the sandiness and oil yield of salted separated egg yolk.

Alkaline amino acids present unique aggregation behavior for quinoa protein gelation under microwave irradiation

This research focused on the unique aggregation behavior of l-Lysine (L-Lys) and l-Arginine (L-Arg) on quinoa protein (QP) gelation under microwave (MW) irradiation. The results of pH and conductivity manifested that the discrepancy of the influence of two alkaline amino acids on protein was due to the diversity of their electrochemical characteristics rather than to aggregation induced by pH-dominated acid-base transitions. Solubility, turbidity and particle size, ζ-potential results exhibited that L-Lys enhanced the ordered aggregation of protein induced by MW heating more than L-Arg. Circular dichroism (CD), UV absorption spectra, surface hydrophobicity (H0) and sulfhydryl groups demonstrated that L-Lys denaturized and unfolded proteins more vigorously than L-Arg, exposing more hydrophobic residues and boosting the hydrophobicity of the protein's surface. These findings emphasized that L-Lys and MW had a more pronounced synergistic effect on the strength and water holding capacity (WHC) of protein gels than L-Arg. Scanning electron microscopy (SEM) also revealed a denser porous network microstructure in the QP gels with L-Lys added.

Use of computational and wet lab techniques to examine the molecular association between a potent hepatitis C virus inhibitor, PSI-6206 and human serum albumin.

This study explores the plausible molecular interaction between a potent hepatitis C virus inhibitor, PSI-6206 (PSI), and human serum albumin (HSA), a primary transporter in blood plasma. Results obtained from both computational viz. molecular docking and molecular dynamics (MD) simulation and wet lab techniques such as UV absorption, fluorescence, circular dichroism (CD), and atomic force microscopy (AFM) complemented each other. While docking results identified PSI binding to subdomain IIA (Site I) of HSA by forming six hydrogen bonds, MD simulations signified the complex stability throughout the 50,000ps. A consistent cutback in the Stern-Volmer quenching constant (Ksv) along with rising temperatures supported the static mode of fluorescence quenching in response to PSI addition and implied the development of the PSI-HSA complex. This discovery was backed by the alteration of the HSA UV absorption spectrum, a larger value (>1010 M-1.s-1) of the bimolecular quenching rate constant (kq) and the AFM-guided swelling of the HSA molecule, in the presence of PSI. Moreover, the fluorescence titration results revealed a modest binding affinity (4.27-6.25×103 M-1) in the PSI-HSA system, involving hydrogen bonds, van der Waals and hydrophobic interactions, as inferred from ΔS = + 22.77Jmol-1 K-1 and ΔH = - 11.02 KJ mol-1values. CD and 3D fluorescence spectra reminded significant adjustment in the 2° and 3° structures and modification in the Tyr/Trp microenvironment of the protein in the PSI-bound state. The results obtained from drug competing experiments also advocated the binding location of PSI in HSA as Site I.

A sustainable approach for the degradation kinetics study and stability assay of the SARS-CoV-2 oral antiviral drug Molnupiravir

Molnupiravir (MPV) is the first direct-acting oral antiviral drug that effectively decreases nasopharyngeal infections with SARS-CoV-2 virus. The stability of MPV was tested by subjecting the drug to various stress conditions. The drug is liable to oxidative, acidic, and alkaline degradation and showed significant stability against thermal degradation. Mass spectrometry identified the degradation products and guided suggestion of the degradation patterns. Interestingly, while inspecting the UV-absorption spectra, we observed no absorbance at 270 nm for the products of the three degradation pathways (c.f. intact MPV). Direct spectrophotometry seemed a solution that perfectly fit the purpose of the stability assay method in our case. It avoids sophisticated instrumentation and complex mathematical data manipulation. The method determined MPV accurately (100.32% ± 1.62) and selectively (99.49% ± 1.63) within the linear range of 1.50 × 10–5–4.0 × 10–4 M and down to a detection limit of 0.48 × 10–5 M. The proposed method is simple and does not require any preliminary separation or derivatization steps. The procedure proved its validity as per the ICH recommendations. The specificity was assessed in the presence of up to 90% degradation products. The study evaluated the greenness profile of the proposed analytical procedure using the National Environmental Methods Index (NEMI), the Analytical Eco-Scale, and the Green Analytical Procedure Index (GAPI). The three metrics unanimously agreed that the developed procedure results in a greener profile than the reported method. The method investigated the degradation reactions' kinetics and evaluated the reaction order, rate constant, and half-life time for each degradation process.

Improvement of functional characteristics of Hypophthalmichthys molitrix protein by modification with chitosan oligosaccharide.

In the food processing field, it is very often that fish proteins are denatured affecting the nutritional value of the product which is vital to be solved. By using appropriate sugar donors for glycosylation with protein, improving the stability and emulsification properties of fish proteins can be achieved. This research looks into the impacts of enzymatic chitosan oligosaccharide (CO) at various concentration (0.15%, 0.30%, 0.45%, 0.60%, w/v) upon the molecular makeup and function of silver carp myofibrillar protein (MP) in an attempt to comprehend the impact of electrostatic binding among MP as well as CO on protein conformation. Analysis was done on the impact of various CO concentrations upon MP's secondary structure, conformational changes, and functional characteristics. Twelve sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assays were implemented to monitor MP; Fourier transform infrared spectroscopy, endogenous fluorescence spectroscopy, and UV absorption spectra were carried out to investigate the influence of CO on MP; Particle size distribution, emulsifying activity index (EAI), solubility, turbidity, sulfhydryl content, carbonyl content, foaming capacity, surface hydrophobicity, emulsifying stability index (ESI), and foam persistence were all investigated. In addition, we used dynamic light scattering, scanning electron microscope, and atomic force microscope to analyze myosin (MO) and 0.60% CO-MO complex. The results demonstrated that CO and MP form complexes through hydrogen bonding and electrostatic interactions. CO modification not only delayed the oxidation of MP but also promoted MP to show better solubility, foaming, and foaming stability. In addition, CO modified myosin particle size decreased, reducing myosin's roughness and making myosin's structure more compact. To sum up, molecular interaction could change functional characteristics, and products with special properties could be developed after modification with chitosan oligosaccharide.

XQR-30: The ultimate XSHOOTER quasar sample at the reionization epoch

ABSTRACT The final phase of the reionization process can be probed by rest-frame UV absorption spectra of quasars at z ≳ 6, shedding light on the properties of the diffuse intergalactic medium within the first Gyr of the Universe. The ESO Large Programme ‘XQR-30: the ultimate XSHOOTER legacy survey of quasars at z ≃ 5.8–6.6’ dedicated ∼250 h of observations at the VLT to create a homogeneous and high-quality sample of spectra of 30 luminous quasars at z ∼ 6, covering the rest wavelength range from the Lyman limit to beyond the Mg ii emission. Twelve quasar spectra of similar quality from the XSHOOTER archive were added to form the enlarged XQR-30 sample, corresponding to a total of ∼350 h of on-source exposure time. The median effective resolving power of the 42 spectra is R ≃ 11 400 and 9800 in the VIS and NIR arm, respectively. The signal-to-noise ratio per 10 km s−1 pixel ranges from ∼11 to 114 at λ ≃ 1285 Å rest frame, with a median value of ∼29. We describe the observations, data reduction, and analysis of the spectra, together with some first results based on the E-XQR-30 sample. New photometry in the H and K bands are provided for the XQR-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the sample. The composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first Gyr of the Universe.

Polymer incorporated with graphene oxide composite for high electrochemical performance

In this present work the Polyaniline/Graphene Oxide composite (PANI/GO) synthesized by chemical polymerization. XRD pattern shows crystal plane (200) and (002) reveals the presence of GO in the PANI/GO composite, UV-absorption spectra exhibits three distinguished peaks at 235 nm is corresponding to the π to π* transition of C–C in GO, 354 nm and 642 nm indexed with bi-polaronic transition of PANI in red shift, surface morphology revels the PANI homogenously dispersed on the surface of GO. CV curve indicates the PANI/GO composite electrode current rate and surface area 5 fold higher than the PANI electrode, which is suggested that the PANI/GO composite electrode is highly suitable for energy storage devices. EIS spectra show the semi-circle arc, and Rct value of PANI is found to be 28.61 Ω and PANI/GO composite electrode found to be 16.15 Ω. These results represent the PANI/GO composite electrode having more storage capacitive than the PANI, it shows high electrical conductivity, and also enhances the electrochemical performance.

Simulation of the VUV Absorption Spectra of Oxygenates and Hydrocarbons: A Joint Theoretical–Experimental Study

Vacuum UV absorption spectroscopy is regularly used to provide unambiguous identification of a target species, insight into the electronic structure of molecules, and quantitative species concentrations. As molecules of interest have become more complex, theoretical spectra have been used in tandem with laboratory spectroscopic analysis or as a replacement when experimental data is unavailable. However, it is difficult to determine which theoretical methodologies can best simulate experiment. This study examined the performance of EOM-CCSD and 10 TD-DFT functionals (B3LYP, BH&HLYP, BMK, CAM-B3LYP, HSE, M06-2X, M11, PBE0, ωB97X-D, and X3LYP) to produce reliable vacuum UV absorption spectra for 19 small oxygenates and hydrocarbons using vertical excitation energies. The simulated spectra were analyzed against experiment using both a qualitative analysis and quantitative metrics, including cosine similarity, relative integral change, mean signed error, and mean absolute error. Based on our ranking system, it was determined that M06-2X was consistently the top performing TD-DFT method with BMK, CAM-B3LYP, and ωB97X-D also producing reliable spectra for these small combustion species.

Synthesis of mediator free hollow BiFeO3 spheres/porous g-C3N4 Z-scheme photocatalysts for CO2 conversion and Alizarin Red S degradation

In this current research work, we fruitfully prepared a mediator-free BiFeO3 hollow spheres/porous g-C3N4 Z-scheme based photocatalysts and utilized it for CO2 conversion and Alizarin Red S degradation. Remarkably, the porous g-C3N4 are prepared by acidic treatment and double calcination method, while BiFeO3 hollow spheres are prepared by employing carbon nanospheres as hard templates. Our results demonstrated that porosity and hollow spheres efficiently upgraded the surface area, light absorption capacity, and photocatalytic activities of g-C3N4 and BiFeO3. Based on electrochemical impedance spectroscopy (EIS), SPS, TEM, FS spectrum associated with the formed •OH amount, and UV-absorbance spectra, it is confirmed that coupling of BiFeO3 hollow spheres with porous g-C3N4 not only thermodynamically provide a suitable platform for receiving the high energy level electrons but also enhanced charge separation. Compared to pristine P–CN, the most optimal sample, 6HBFO/P–CN, showed a 3.5-times enhancement in activities for Alizarin Red S decontamination and CO2 conversion under visible light irradiation. Finally, our present work will open a new gateway to synthesize BiFeO3 hollow spheres/porous g-C3N4 Z-scheme materials as effective photocatalysts for organic contaminants decontamination and CO2 conversion.

Ultrafast non-adiabatic dynamics of stilbene-based plant-derived sunscreens with cis–trans isomerization structures

In this work, we investigated the potential UV protection mechanism of the natural compounds hydroxy resveratrol and pterostilbene by combining theoretical calculations and femtosecond transient absorption spectra (FTAS). The UV absorption spectra showed that the two compounds exhibited strong absorption properties and high photostability. We found two molecules will reach the S1 state or an even higher excited state after UV exposure and molecules in S1 will cross a lower energy barrier to reach the conical intersection. The adiabatic trans–cis isomerization process happened and finally return to the ground. Meanwhile, FTAS clarified the time scale of trans–cis isomerization of two molecules was ∼ 10 ps, which also met the requirement of fast energy relaxation. This work also provides theoretical guidance for developing new sunscreen molecules from natural stilbene.

A TMVP1-modified near-infrared nanoprobe: molecular imaging for tumor metastasis in sentinel lymph node and targeted enhanced photothermal therapy

BackgroundTMVP1 is a novel tumor targeting polypeptide screened by our laboratory with a core sequence of five amino acids LARGR. It specially binds to vascular endothelial growth factor receptor-3 (VEGFR-3), which is mainly expressed on neo-lymphatic vessels in sentinel lymph node (SLN) with tumor metastasis in adults. Here, we prepared a targeted nanoprobe using TMVP1-modified nanomaterials for tumor metastasis SLN imaging.ResultsIn this study, TMVP1-modified polymer nanomaterials were loaded with the near-infrared (NIR) fluorescent dye, indocyanine green (ICG), to prepare a molecular imaging TMVP1-ICG nanoparticles (NPs) to identify tumor metastasis in SLN at molecular level. TMVP1-ICG-NPs were successfully prepared using the nano-precipitation method. The particle diameter, morphology, drug encapsulation efficiency, UV absorption spectrum, cytotoxicity, safety, and pharmacokinetic properties were determined. The TMVP1-ICG-NPs had a diameter of approximately 130 nm and an ICG loading rate of 70%. In vitro cell experiments and in vivo mouse experiments confirmed that TMVP1-ICG-NPs have good targeting ability to tumors in situ and to SLN with tumor metastasis by binding to VEGFR-3. Effective photothermal therapy (PTT) with TMVP1-ICG-NPs was confirmed in vitro and in vivo. As expected, TMVP1-ICG-NPs improved ICG blood stability, targeted tumor metastasis to SLN, and enhanced PTT/photodynamic (PDT) therapy, without obvious cytotoxicity, making it a promising theranostic nanomedicine.ConclusionTMVP1-ICG-NPs identified SLN with tumor metastasis and were used to perform imaging-guided PTT, which makes it a promising strategy for providing real-time NIR fluorescence imaging and intraoperative PTT for patients with SLN metastasis.

The Influence of NiO Nanoparticles on Structural, Optical and Dielectric Properties of CMC/PVA/PEDOT:PSS Nanocomposites

The solution casting process was used to fabricate nanocomposite samples composed of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and filled with varied concentrations of nickel oxide nanoparticles (NiO NPs). The effect of NiO nanoparticles on the structural, optical, and electrical properties of the pure CMC/PVA/PEDOT:PSS mixture was studied and discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis revealed that the NiO NPs are cubic in phase and range in size from 10 to 55 nm. The XRD analysis of the incorporated films indicated that the NiO NPs crystallinity increased at expense of the CMC/PVA/PEDOT:PSS composites. Fourier Transform Infrared (FTIR) examination revealed the main absorption vibrational peaks of CMC, PVA, PEDOT:PSS, and Ni-O, whose intensities changed randomly after filling, revealing the intermolecular interaction between the nanocomposite components. The UV and visible range absorption spectra showed a sharp peak around 228 for the pure blend, which can be assigned to the π→π* transition. After being filled with NiO NPs, the nanocomposites produced displayed new peaks at 292 and 422 nm that steadily increased with increasing NiO NPs concentration. The optical energy gap (Eg) was computed, and it was discovered that when the NiO NPs content increased, the Eg decreased (from 4.88 to 4.06 eV). At room temperature and over a wide frequency range, between 10− 1 and 107 Hz, the samples’ impedance, AC conductivity, and dielectric qualities were examined. Increased NiO NPs content was seen to gradually enhance dielectric loss (up to 2255), and dielectric constant (up to 311). The AC conductivity of the filled samples is also enhanced and corresponds to Jonscher power law. By analysing impedance components of the Z*, the equivalent electrical circuit for each sample was determined. Because of the considerable improvement in optical and electrical properties, these composite films could compete for usage in optoelectronic applications.

Interaction of isoquinoline alkaloids with pyrimidine motif triplex DNA by mass spectrometry and spectroscopies reveals diverse mechanisms

Isoquinoline alkaloids represent an important class of molecules due to their broad range of pharmacology and clinical utility. Prospective development and use of these alkaloids as effective anticancer agents have elicited great interest. In this study, in order to reveal structure-activity relationship, we present the characterization of bioactive isoquinoline alkaloid-DNA triplex interactions, with particular emphasis on the sequence selectivity and preference of binding to the two types of DNA triplexes, by electrospray ionization mass spectrometry (ESI-MS) and various spectroscopic techniques. The six alkaloids, including coptisine, columbamine, epiberberine, berberrubine, jateorhizine, and fangchinoline, were selected to explore their interactions with the TC and TTT triplex DNA structures. Berberrubine, fangchinoline, coptisine, columbamine, and epiberberine have preference for TC rich DNA sequences compared to TTT rich DNA triplex based on affinity values in MS. The experimental results from different fragmentation modes in tandem MS, subtractive and hyperchromic effects in UV absorption spectra, fluorescence quenching and enhancement in fluorescence spectra, and strong conformational changes in circular dichroism (CD) hinted that the interaction between isoquinoline alkaloid-TC/TTT DNA had diverse mechanisms including at least two different binding modes: the electrostatic binding and the intercalation binding. Interestingly, columbamine, berberrubine, and fangchinoline can stabilize TTT triplex as inferred from optical thermal melting profiles, while it was not the case in TC triplex. These results provide new insights into binding of isoquinoline alkaloids to pyrimidine motif triplex DNA.

Solid-state ion-selective electrodes for the first potentiometric determination of the anti-COVID 19 drug Remdesivir in human plasma; A comparative study

Establishing sensitive and targeted analytical methodologies for drug identification in biological fluids as well as screening of treatments that can counteract the most severe COVID-19 infection-related side effects are of utmost importance. Here, first attempts have been made for determination of the anti-COVID drug Remdesivir (RDS) in human plasma using four potentiometric sensors. Calixarene-8 (CX8) was used as an ionophore applied to the first electrode (Sensor I). The second had a layer of dispersed graphene nanocomposite coating (Sensor II). (Sensor III) was fabricated using nanoparticles of polyaniline (PANI) as ion-to–electron transducer. A reverse-phase polymerization using polyvinylpyrrolidone (PVP) was employed to create a graphene-polyaniline (G/PANI) nanocomposite electrode (Sensor IV). Surface morphology was confirmed by Scanning Electron Microscope (SEM). UV absorption spectra and Fourier Transform Ion Spectrophotometry (FTIR) also supported their structural characterization. The impact of graphene and polyaniline integration on the functionality and durability of the manufactured sensors was examined using the water layer test and signal drift. In the ranges of concentration of 10−7 to 10−2 mol/L and 10−7 to 10−3, sensors II & IV exhibited linear responses; respectively while sensors I & III displayed linearity within 10−6 to 10−2 mol/L. The target drug was easily detectable using LOD down to 100 nmol/L. The developed sensors satisfactorily offered sensitive, stable, selective and accurate estimate of Remdesivir (RDS) in its pharmaceutical formulation as well as spiked human plasma with recoveries ranging from 91.02 to 95.76 % with average standard deviations less than 1.85. The suggested procedure was approved in accordance with ICH recommendations.

Self-actuated biomimetic nanocomposites for photothermal therapy and PD-L1 immunosuppression.

Biomimetic nanocomposites are widely used in the biomedical field because they can effectively solve the problems existing in the current cancer treatment by realizing multi-mode collaborative treatment. In this study, we designed and synthesized a multifunctional therapeutic platform (PB/PM/HRP/Apt) with unique working mechanism and good tumor treatment effect. Prussian blue nanoparticles (PBs) with good photothermal conversion efficiency were used as nuclei and coated with platelet membrane (PM). The ability of platelets (PLTs) to specifically target cancer cells and inflammatory sites can effectively enhance PB accumulation at tumor sites. The surface of the synthesized nanocomposites was modified with horseradish peroxidase (HRP) to enhance the deep penetration of the nanocomposites in cancer cells. In addition, PD-L1 aptamer and 4T1 cell aptamer AS1411 were modified on the nanocomposite to achieve immunotherapy and enhance targeting. The particle size, UV absorption spectrum and Zeta potential of the biomimetic nanocomposite were determined by transmission electron microscope (TEM), Ultraviolet-visible (UV-Vis) spectrophotometer and nano-particle size meter, and the successful preparation was proved. In addition, the biomimetic nanocomposites were proved to have good photothermal properties by infrared thermography. The cytotoxicity test showed that it had a good killing ability of cancer cells. Finally, thermal imaging, tumor volume detection, immune factor detection and Haematoxilin-Eosin (HE) staining of mice showed that the biomimetic nanocomposites had good anti-tumor effect and could trigger immune response in vivo. Therefore, this biomimetic nanoplatform as a promising therapeutic strategy provides new inspiration for the current diagnosis and treatment of cancer.

Characterization of Titanium dioxide (TiO2 ) Nanoparticles Biosynthesized using Leuconostoc spp. Isolated from Cow’s Raw Milk

Nanotechnology is a continually expanding field for its uses and applications in multiple areas i.e. medicine, science, and engineering. Biosynthesis is straightforward, less-toxicity, and cost-effective technology. TiO2 NPs biosynthesis has attained consideration in recent decades. In this study, probiotic bacteria were isolated from cow’s raw milk samples, and then were identified by using the Vitek2 system; as Leuconostoc spp. included Leuconostoc mesenteroides subsp. mesenteroides (Leu.1), Leuconostoc mesenteroides subsp. cremoris (Leu.4), and Leuconostoc pseudomesenteroides (Leu.14). All Leuconostoc spp. isolates showed an ability for TiO2 NPs bio-production, after being incubated at anaerobic conditions (30 o C/ 24 h) in DeMan Regosa and Sharpe (MRS) broth medium. The biosynthesized TiO2 nanoparticles were characterized using the following apparatuses: UV-Vis spectroscopy, X-ray diffraction (XRD) apparatus, Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM) in addition to Energy Dispersive X-ray analysis (EDX) spectra. The characterized biosynthesized TiO2 NPs were spherical-shaped, nanostructure anatase crystals with an average size range of 53.35-59.41 nm. The UV absorption spectrum was observed at the wavelength 344-248 nm; the topography AFM 2D and 3D images result showed the height and roughness of biosynthesized TiO2 NPs that were in the range of 1.137-18.88 nm. Absorption peaks in the FTIR spectra were located in a region typical of TiO2 NPs, and biosynthesized TiO2 nanoparticles’ main IR topographies (408.21- 445.80) cm-1 belonged to anatase Titania (Ti-O-Ti) bridge.