Characteristic Absorption Research Articles

Large depth-of-field ultraviolet-visible photoacoustic histologic and microvascular imaging in vivo

Photoacoustic microscopy (PAM) can image diverse biological microstructures by harnessing characteristic optical absorption spectra of intrinsic nonfluorescent biomolecules. We incorporate ultraviolet (UV) and visible pulsed lasers into a PAM to develop an UV-visible PAM for label-free histologic and microvascular imaging, where the cell nuclei and blood vessels are specifically captured at high contrast relying on strong optical absorption of DNA/RNA and hemoglobin at 266 and 532 nm wavelengths, respectively. Moreover, two diffractive optical elements operating at UV and visible spectra are designed for engineering the excitation beams, significantly enlarging depths of field (DOFs > 200 μm). The UV-visible PAM demonstrates combined capabilities of dual imaging contrast, elongated DOFs, and micrometer-scale lateral resolution for delineating the spatial microarchitectures of both cell nuclei and blood vessels that are at different depth locations in the biological specimens with uneven surfaces. Longitudinal monitoring of the trauma is performed in mouse ear in vivo. Potentially, our UV-visible PAM could offer comprehensive histologic and microvascular information in a broad range of biomedical studies.

Synthesis, characterization and photo catalytic activity of silver nano particle derived from Arachis hypogaea L. seed peel extracts

Abstract The study focuses on the green synthesis of silver nanoparticles (AgNPs) using Arachis hypogaea L. seed peel extract (AHSPE) and evaluates their photocatalytic activity against Rhodamine B and Congo Red dyes. The synthesis involved reducing aqueous silver metal ions with AHSPE, characterized by various techniques including UV–visible spectroscopy, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and FT-Raman spectroscopy. UV–visible spectroscopy indicated characteristic absorption peaks at 428 and 439 nm, confirming the formation of AgNPs. XRD analysis revealed an average particle size of 4.77–5.6 nm. FT-IR spectra identified biomolecules such as amines, peptides, amides, lactones, and polyphenols in the extract, acting as reducing and capping agents, thereby stabilizing the AgNPs. SEM analysis showed pristine silver nanoparticles with diameters ranging from 1 to 10 µm. The biosynthesized AgNPs demonstrated strong photocatalytic activity in degrading Rhodamine B and Congo Red dyes. This method did not use any synthetic reagents, making it an environmentally safe and cost-effective alternative for synthesizing silver nanoparticles. The process aligns with green chemistry principles, offering potential applications in photocatalysis and environmental cleanup. The study underscores the importance of biosynthesized nanoparticles due to their unique biological properties and the role of plant secondary metabolites in facilitating green synthesis.

Comparison of a Quantum Cascade Laser and an Interband Cascade Laser for the Detection of Stable Carbon Dioxide Isotopes Using Tunable Laser Absorption Spectroscopy

Quantum cascade lasers (QCLs) and interband cascade lasers (ICLs) are widely used as light sources in tunable laser absorption spectroscopy because they emit in the mid-infrared region where many strong and characteristic absorption bands are present. In this paper, we compare the performance of these lasers emitting at about 2310.1 cm–1 to determine an optimal light source for detecting isotopic ratios of carbon dioxide (CO2). Our results show that the QCL has a higher relative intensity noise of up to 15 dBc/Hz compared to the ICL over the entire measured frequency range. In addition, it has a higher frequency fluctuation. However, the maximum tuning range of the QCL is up to 5.2 cm–1 compared to up to 3.8 cm–1 for the ICL. Both lasers lose more than half of their tuning range when the tuning rate is increased to 10 kHz. When measuring the isotope ratio of CO2, an uncertainty in the [Formula: see text] value of [Formula: see text]‰ was achieved with the ICL and of [Formula: see text]‰ with the QCL, both at an integration time of 0.2 s. In summary, the QCL is more appropriate for applications that require a larger spectral tuning range, such as the measurement of a complex gas mixture, while the ICL has an excellent signal-to-noise ratio and is therefore better suited for applications that require higher precision.

Comparative bioavailability study of supplemental oral Sucrosomial® vs. oral conventional vitamin B12 in enhancing circulatory B12 levels in healthy deficient adults: a multicentre, double-blind randomized clinical trial

BackgroundVitamin B12 is essential for neurological function, red blood cell formation, and DNA synthesis. Deficiency can lead to diverse health conditions, including megaloblastic anemia and neurological issues. Oral supplementation is a standard treatment for B12 deficiency. The Sucrosomial® carrier system offers an innovative approach that enhances supplemental nutrient absorption and bioavailability.ObjectivesThis study aimed to compare the effectiveness of oral Sucrosomial® vitamin B12 formulation vs various conventional B12 supplements, randomly selected from local pharmacies, in increasing and maintaining circulatory B12 levels in healthy deficient adults (200–300 pg/mL).MethodsA randomized, double-blind clinical trial was conducted across three centers in Pakistan from April to July 2024. At KEMU, participants received either Sucrosomial® vitamin B12 or Mecogen SL B12; at LRH, Sucrosomial® B12 or B-SUB B12; and at LUMHS, Sucrosomial® B12, Evermin B12, or Neuromax B12. Participants took a daily single dose of 1,000 μg of the assigned B12 formulation for 7 days. Serum B12 levels were measured at baseline (day 0) and on days 1, 3, 5, and 7.ResultsSucrosomial® B12 was significantly more effective than conventional B12 formulations in increasing and maintaining higher serum B12 levels across all time points. At KEMU, it reached a peak concentration of 454 ± 3.9 pg/mL by day 5, compared to 274 ± 11.1 pg/mL with Mecogen SL B12. At LRH, it peaked at 496 ± 34.4 pg/mL by day 5 versus 304 ± 49.4 pg/mL for B-SUB B12. At LUMHS, it reached 592.7 ± 74.3 pg/mL by day 7, compared to 407.24 ± 41.6 pg/mL for Evermin B12 and 263.82 ± 23.8 pg/mL for Neuromax B12. Sucrosomial® B12 was the only formulation to surpass the deficiency-borderline threshold (200–300 pg/mL) within 24 h of the first dose and was well tolerated with no reported side effects.ConclusionSucrosomial® vitamin B12 demonstrated superior efficacy in rapidly and consistently elevating and maintaining higher circulatory B12 levels compared to conventional supplements. Its characteristic absorption mode and proven efficacy suggest it could effectively address B12 deficiency in a broad range of populations, including those with gastrointestinal conditions and pernicious anemia, thereby supporting overall health.Clinical trial registrationclinicaltrials.gov, NCT06376591.

Nanotube formation and coating of hydroxyapatite-polyvinyl alcohol-collagen composite on Ti-6Al-4V metal alloy

Abstract Ti-6Al-4V metal is widely used as an implantable material due to its biocompatibility and corrosion resistance; however, it has low bioactive properties. The formation of nanotubes and a hydroxyapatite-polyvinyl alcohol-collagen composite coating on Ti-6Al-4V metal aims to enhance its biocompatibility and bioactivity. The nanotube oxide layer Ti-6Al-4V was formed by the anodization method. The composite’s infrared spectrum showed characteristic absorption bands from Hydroxyapatite (HAp), polyvinyl alcohol, and collagen. The composite-coated Ti-6Al-4V metal, both non-nanotube, and nanotube, showed a typical diffraction pattern of HAp and titanium element. The electron microscope image showed the uniform granular form of HAp. The corrosion test results showed that composite-coated nanotube Ti-6Al-4V metal could not improve corrosion resistance. It is also relevant to the in vitro test in a lactate ringer solution that showed the higher Ca2+ ion of nanotube Ti-6Al-4V metal than that of non-nanotube Ti-6Al-4V metal.

Antibacterial and Photocatalytic Applications of Silver Nanoparticles Synthesized from Lacticaseibacillus rhamnosus

The biosynthesis of silver nanoparticles (AgNPs) presents an innovative and sustainable approach in nanotechnology with promising applications in fields such as medicine, food safety, and pharmacology. In this study, AgNPs were successfully synthesized using the probiotic strain Lacticaseibacillus rhamnosus (BCRC16000), addressing challenges related to stability, biocompatibility, and scalability that are common in conventional nanoparticle production methods. The formation of AgNPs was indicated by a color change from yellow to brown, and UV–visible spectrophotometry confirmed their presence with a characteristic absorption peak at 443 nm. Furthermore, Fourier transform infrared (FTIR) spectroscopy revealed the involvement of biomolecules in reducing silver ions, which suggests their role in stabilizing the nanoparticles. In addition, field emission scanning electron microscopy (FE-SEM) showed significant morphological and structural changes. At the same time, dynamic light scattering (DLS) and zeta potential analyses provided valuable insights such as average size (199.7 nm), distribution, and stability, reporting a polydispersity index of 0.239 and a surface charge of −36.3 mV. Notably, the AgNPs demonstrated strong antibacterial activity and photocatalytic efficiency, underscoring their potential for environmental and biomedical applications. Therefore, this study highlights the effectiveness of Lacticaseibacillus rhamnosus in the biosynthesis of AgNPs, offering valuable antibacterial and photocatalytic properties with significant industrial and scientific implications.

Structural analysis of Pleurotus ferulae polysaccharide and its effects on plant fungal disease and plant growth

A novel polysaccharide, named as PFP1–1 (23 kDa), was isolated from the fruiting body of Pleurotus ferulae. Structural analysis revealed that PFP1–1 is primarily composed of mannose, galactose, glucose and fucose, with a molar ratio of 41.50:41.92:4.65:1.93. Infrared spectroscopy analysis showed the presence of characteristic absorption peaks associated with polysaccharides. Further analysis using gas chromatography–mass spectrometry (GC–MS) and Nuclear Magnetic Resonance (NMR) indicated that the polysaccharide mainly composed of → 6) -α-D-Galp- (1 →, → 2,6) -α-D-Galp- (1 → and a small amount of → 4) -α-D-Glcp- (1 →. The branched chain is mainly composed of β-D-Manp- (1 → and α-D-Glcp- (1 → connected at the O-2 position of the sugar residue → 2,6) -α-D-Galp- (1 →. PFP1–1 exhibited significant antifungal activity against Rhizoctonia solani and promoted cucumber plant growth. The mycelial growth inhibition rate of PFP1–1 against R. solani reached 70 %. In pot experiments, cucumber seedlings treated with PFP1–1 demonstrated resistance to R. solani infection and the incidence rate was significantly reduced to 22.92 %. PFP1–1 increased the root length and fresh weight of cucumber seedlings and enhanced the stress and disease resistance of plants by increasing the activities of superoxide dismutase, peroxidase and polyphenol oxidase. In conclusion, the present study provides a theoretical and experimental basis for the application of P. ferulae polysaccharide in promoting plant growth and controlling plant diseases.

A Novel Chemical Approach for the Development of Thioesterified Cellulose Derivatives

In this study, thioesterified cellulose was synthesized by grafting thiol moiety onto a-cellulose, which was first oxidized with different reactive oxygen species (ROS) such as H2O2, Fenton reagent (FR), and peroxyacetic acid in aqueous solution. The thioesterification was done by refluxing oxidized cellulose with ethanedithiol in a mixture of toluene and water (4:1) at 85°C for 6 h. The modification of cellulose was evidenced by FTIR, Raman, solid-state 13C CP MAS NMR spectroscopy, conductometric titration, thermogravimetric analysis, X-ray diffraction, zeta potential measurement, molecular weight determination, and SEM analysis. The characteristic absorption bands for −C=O and −C(=O)−S− bonds in FTIR and Raman spectra were suggestive of the modification of cellulose. 20 % FR was the most efficient in introducing the highest amount (158.93 μmol g−1) of the -COOH groups, while cleavage of cellulose backbone was found to take place as evidenced by the result of the degree of polymerization. The presence of new peaks in 13C CP MAS NMR spectra of thiol-functionalized cellulose ascertained the anchoring of thiol onto oxidized cellulose. Additionally, the significant decrease in the C6 signals for the amorphous region of thiol-modified cellulose provided information about successful modification. In addition, the degree of substitution was determined to be about 0.025. The efficacious functionalization was further supported by the measurement of zeta potential, wherein thioesterified cellulose exhibited the highest negative zeta potential due to increased hydrophobicity. This study would open up a new route for the development of important derivatives of cellulose, including cellulose dimer, containing the thioester group which is the backbone of many antibiotics and natural products.

Green Synthesis, Characterization and Pharmaceutical Applications of Biocompatible Zinc Oxide Nanoparticles Using Heliotropium rariflorum Stocks

Background: Zinc oxide nanoparticles are safe, non-toxic, and biocompatible. These NPs are used in food packaging materials, self-cleaning glass, ceramics, deodorants, sunscreens, paints, coatings, ointments, lotions, and as preservatives. This study explored the biological potential of ZnO nanoparticles synthesized using H. rariflorum. Methods: In vitro antibacterial and antifungal activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans, Penicillium notatum, Aspergillus flavus, Aspergillus niger and Aspergillus solani were determined. Antioxidant activity was explored using the DPPH radical scavenging method. In vivo analgesic, antipyretic and sedative potential of synthesized nanoparticles was investigated using a mouse model. Results: SEM with various magnification powers showed that some particles were spherical while some were aggregated, flake-shaped, and hexagonal with rough and irregular surfaces. The EDX analysis revealed Zn (12.63%), O (22.83%) and C (63.11%) with trace quantities of Si (0.40%), Ca (0.54%) and P (0.49%). The XRD pattern indicated an amorphous state, with no peaks observed throughout the spectrum. The UV–visible spectrophotometry revealed a characteristic absorption peak at 375 nm, indicating the presence of ZnO nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) displayed several small peaks between 1793 and 2370 cm−1, providing evidence of the presence of different kinds of organic compounds with different functional groups. ZnO-NPs showed dose-dependent antibacterial and antifungal potential against all strains. Staphylococcus aureus and Candida albicans were the most susceptible strains. The nanoparticles exhibited a maximum antioxidant effect of 85.28% at 100 μg/mL. In this study, the acute toxicity test showed no mortality, and normal behavior was observed in mice at ZnO-NP doses of 5, 10, and 20 mg/kg. For analgesic and antipyretic activities, a two-way ANOVA revealed that dose, time, and the interaction between dose and time were significant. In contrast, the samples had a non-significant effect on sedative activity. Conclusions: This innovative study suggests a potential use of plant resources for managing microbes and treating various diseases, providing a scientific basis for the traditional use of H. rariflorum.

Sustainable enhancement of wool fibers using Hymenocrater platystegius flower and natural dyes for improved Insect-Repellent and color properties

This study investigates the application of Hymenocrater platystegius flower as a natural mothproofing agent for wool fibers and examines the effects of aluminum mordanting on the dyeing properties of wool treated with various natural dyes. Wool fibers were treated with Hymenocrater platystegius flower powder and aluminum salts, followed by dyeing with Madder, Reseda lutea, Indigo, or Walnut shell dyes using different mordanting methods. FTIR analysis revealed the characteristic absorption bands and confirmed the interactions between the wool fibers and the treatment agents. The insect-repellent properties were assessed by weight loss measurements after exposure to Anthrenus verbasci larvae, showing significant improvements in treated samples, particularly with the combination of Hymenocrater platystegius and aluminum mordanting. GC–MS analysis of the essential oil identified as α-Pinene, Trans-Verbenol, Linalool, and β-Bourbonene as the main constituents, contributing to the insect-repellent effect. The L*a*b* color space analysis demonstrated that aluminum mordanting significantly enhances the color strength and stability of dyed wool, with pre-mordanting generally providing better results. The study further evaluated the washing and light fastness, as well as the mothproofing properties of the dyed wool samples. These results indicate that the weight loss percentages of treated wool fiber after washing are slightly higher than before washing, but the difference is not significant. Overall, the use of aluminum mordant in conjunction with Hymenocrater platystegius flower powder not only improves the color characteristics of wool dyed with natural dyes but also provides effective mothproofing properties, making it a viable and eco-friendly option for textile applications.

Investigation of antibacterial and anticancer activities of biosynthesized metal-doped and undoped zinc oxide nanoparticles.

Over the past 10 years, nanotechnology has emerged as a very promising technique for a wide range of biomedical applications. Green synthesized metal and metal oxide nanoparticles (NPs) are cheap, easy to produce in large quantities, and safe for the environment. Currently, efforts are being made to dope ZnO in order to improve its optical, electrical, and ferromagnetic qualities as well as its crystallographic quality. Actually, doping is one of the simplest methods for enhancing an NP's physicochemical characteristics because it involves introducing impure ions into the crystal lattice of the particle. In this study, the biosynthesis of zinc oxide NPs (ZnONPs) and metal-doped (Mg2+ and Ag+) ZnONPs was carried out by using aqueous and water-alcoholic extracts of Cynara scolymus L. leaves, Carthamus tinctorius L. flowers, and Rheum ribes L. (RrL) plant, which are rich in phytochemical content. Plant extracts act as a natural reducing, capping, and stabilizing agent in the production. The produced NPs were characterized using a variety of methods, such as ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM). The produced metal-doped and undoped ZnONPs exhibited characteristic absorption peaks between 365 and 383nm due to their surface plasmon resonance bands. SEM analysis revealed that the NPs were oval, nearly spherical, and spherical. In the FTIR spectra, the Zn-O bonding peak ranges from 400 to 700cm-1. The peaks obtained in the range of 407-562cm-1 clearly represent the Zn-O bond. In addition, the FTIR results showed that there were notable amounts of phenol and flavonoid compounds in both the prepared extract and ZnONPs. According to DLS analysis results, the size distribution of produced NPs is between 120 and 786nm. The antibacterial properties of green produced NPs on Gram-positive (Staphylococcus aureus RN4220) and Gram-negative (Escherichia coli DH10B) bacterial strains were investigated by agar well diffusion method. In studies investigating the anticancer activities of biosynthesized NPs, mouse fibroblast cells (L929) were used as healthy cells and human cervical cancer cells (HeLa) were used as cancer cells. Only the produced Ag-ZnONPs showed potent dose-dependent antibacterial activity (at concentrations higher than 100µg/mL) against Gram-positive and Gram-negative bacteria. RrL-ZnONP-600 and RrL-ZnONP-800 NPs produced with water-ethanol extract of RrL plant and calcined at 600 and 800°C were effective at high concentrations in healthy cells and at low concentrations in HeLa cancer cells, showing that they have the potential to be anticancer agents. The study's findings highlight the potential of green synthesis techniques in the production of medicinal nanomaterials for the treatment of cancer and other biological uses.

Applying Computational Spectroscopy Methods to Raman Spectra of Dicationic, Imidazolium-Based, Ionic Liquids.

Studying ionic liquids (ILs) through computational methods is one of the ways to accelerate progress in the design of novel and potentially green materials optimized for task-specific applications. Therefore, it is essential to develop simple and cost-effective computational procedures that are able to replicate and predict experimental data. Among these, spectroscopic measurements are of particular relevance since they are often implicated in structure-property relationships, especially in the infrared spectral region, where characteristic absorption and scattering processes due to molecular vibrations are ultimately influenced by the surrounding environment in the condensed phase. In this frame, we validate, vis-à-vis experimental data, an efficient theoretical method to compute the Raman spectra in the liquid phase of four especially synthesized dicationic ionic liquids and to assess the conformational cation/anion contributions to the experimental bands. The computational procedure is based on the assessment of the most probable conformations as evaluated by a computational protocol involving both molecular dynamics and ab initio methods.

Temperature Effects on the Optical Properties of Bismuth Nanoparticles Prepared by PLAL for Antibacterial Activity

Bismuth nanoparticles (Bi NPs) constitute a promising technology for combating infectious illnesses and bacterial resistance to antibacterial treatments. Bi NPs were synthesized by Pulsed Laser Ablation in Liquid (PLAL) using a 532 nm second-harmonic generation Nd:YAG laser. Bi NPs samples were prepared in 10, 35, 50, 75, and 90 ˚C water for various laser energies and number of laser pulses. Ultraviolet-visible (UV-Vis) spectra measurements revealed a characteristic plasmonic absorption band indicative of metallic bismuth nanosized particles. Field emission scanning electron microscopy (FESEM) analysis showed that the water temperature during the ablation process affected the size and morphology of Bi NPs. The average Bi NP size at 60 ˚C was 28 nm, considerably smaller than the 55 nm average observed at 10 ˚C. The antimicrobial properties of Bi NPs against two opportunistic pathogens, E. coli and S. aureus, were assessed. For S. aureus, the inhibition zone of Bi NPs prepared at 60 ˚C was greater than that of samples prepared at 10 ˚C. Further, Bi NPs exhibited lower potency against E. coli than S. aureus in both samples.

Lignin‐based nitrogen and phosphorus‐containing polylactic acid with flame‐retardant performances

AbstractPolylactic acid (PLA) is a new type of biodegradable material that has been applied in many fields such as extrusion, injection molding, film drawing, and spinning. In contrary, it does not have flame retardancy. In this paper, N‐PCDL was synthesized by amidation reaction between COOH of PCDL and NH2 of tetraethylenepentamine (TEPA), followed by an Atherton‐Todd reaction of unreacted NH2 at the other end of TEPA with PH of DOPO to prepare a novel lignin‐based flame retardant containing nitrogen and phosphorus (NP‐PCDL). The Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic hydrogen spectroscopy (1H NMR) analysis results showed that proton peaks of CONH, PN, and NH appeared in the NP‐PCDL spectrum, while the characteristic absorption peak of PH bond disappeared in DOPO, the X‐ray photoelectron spectroscopy (XPS) results showed that the degraded lignin consisted of elements C and O, while NP‐PCDL consisted of elements C, O, N and P. The above results indicated that NP‐PCDL was successfully prepared. NP‐PCDL accounted for 3% (mass percentage, the same below), 5% and 10% of PLA, then lignin based flame‐retardant PLA composites were prepared by internal mixing and injection molding. Thermogravimetric analysis (TGA) showed that the residual carbon of PLA/3% NP‐PCDL, PLA/5% NP‐PCDL and PLA/10% NP‐PCDL at 800°C were higher than that of pure PLA, with the increase of 56.56%, 97.54%, and 301.64%, respectively; The analysis of SEM, XPS, and Raman showed that PLA/NP‐PCDL formed dense, regular and highly graphitized residual carbon with phosphorus nitrogen structure during the combustion process. At the same time, NH3, H2O and PO˙ free radicals were released, which could dilute combustible gases, destroy free radical chain reaction, isolate combustible gases and heat, so as to play a flame‐retardant role.

Rapid Method for Simultaneous Determination of γ-Oryzanol Compounds in Rice (Oryza sativa) Grains using UV-Vis Spectroscopy and Chemometrics

Rice (Oryza sativa) contains γ-oryzanol, which consists of 4 main compounds: Cycloartenol ferulate, 2,4-methylenecycloartanyl ferulate, campesterol ferulate, and β-sitosterol ferulate, that contribute to the health benefits of rice. This research aimed to develop a rapid method to determine the 4 major γ-oryzanol compounds in 45 varieties covering pigmented (black and red) and non-pigmented (white) rice grain. The method was developed by integrating UV-Vis spectroscopy with chemometrics, specifically principal component analysis (PCA) and partial least square (PLS) regression. Sampling was performed across the Indonesian archipelago collecting 180 samples, which comprises 60 samples for each type of rice in form of rice husk, bran, whole grain, and polished rice. The results of PCA on the spectroscopic data successfully identified distinction for the 3 types of rice attributable by different type and levels of chemical compound in the grain. White rice exhibited a characteristic absorption at 325 nm while in pigmented (red and black) rice showed a maximum absorbance at 280 nm, indicating the presence of different composition of chemical compounds. A reliable model to predict the 4 major γ-oryzanol compounds was established with R2 calibration, R2 cross-validation, and R2 prediction higher than 0.9 was obtained using the spectroscopic data in the range from 200 to 400 nm. However, the PLS modeling was unsuccessful for red and black rice samples most likely due to the interfering high absorption of red colored compounds. Compared to the existing techniques for analyzing individual compounds of the γ-oryzanol by high-performance liquid chromatography, the newly developed approach using UV-Vis spectroscopy combined with chemometrics is more practical, faster, and cost-efficient and mainly, solvent and residues free. HIGHLIGHTS A rapid method was developed to determine 4 major γ-oryzanol compounds in rice. This method integrates UV-Vis spectroscopy with PCA and PLS regression chemometrics. PCA successfully identified the distinction among white, red, and black rice types. Reliable PLS models were established for white rice with R2 values above 0.9. The developed approach is more practical, faster, and residue-free than HPLC. GRAPHICAL ABSTRACT

A magnetic SERS-imprinted sensor for the determination of cardiac troponin I based on proteolytic peptide technology

Acute myocardial infarction is a sudden and high-mortality disease that can be accurately diagnosed by measuring the level of cardiac troponin I in the blood. Currently, cTnI commonly used clinical detection methods usually have excellent sensitivity and are suitable for large-scale sample detection analysis. However, most of these methods are operated through multiple steps of fixation, incubation, reaction and separation, and most of them require professionals to operate complex instruments, which greatly limits their applicability in real-time rapid detection. Therefore, a method that requires low professional skills and can perform rapid detection is necessary. We presents an alternative strategy to quantify cTnI in clinical serum samples using a combination of SERS and magnetic molecularly imprinted polymers (MMIP). MMIPs was synthesized under Polyvinyl Pyrrolidone (PVP) conditions without vinyl modification using characteristic peptide as template, MAA and DMAm as functional monomers. The internal Raman probe 4-MBA was connected through Ag-SH bonds in MMIPs to solve the problem that the target object had no Raman characteristic peak. MMIPs with high magnetic and adsorptive properties showed characteristic absorption peaks at the Raman shift of 1582 cm−1 after specific capture of the target templates. The Raman signals of the 4-MBA were reduced due to shielding effects and the detection range of this method was 0.001–100 ng mL−1. The recoveries and relative standard deviations (RSDs) of the spiked experiments were 103.1%–106.3 % and 3.54 %–7.38 %, respectively. In summary, this work had appropriate sensitivity and specificity, and there was no significant difference in detection results after ELISA verification. It provided a flexible and practical analysis method for detecting cTnI based on SERS technology. In addition, the imprinting materials of other disease markers can be prepared by changing the template molecules, which provides a new idea for the detection of other biomarkers.

Fe7S8 nanosheets- catalyzed colorimetric and fluorescence dual ratio sensing for high selectivity detection of ascorbic acid

By using Fe7S8 nanosheets (NSs) as catalyst, O-phenylenediamine (OPD) as chromogenic substrate, H2O2 as oxidant, and ascorbic acid (AA) as regulator, a dual ratio colorimetric and fluorescence sensing system for determining AA was constructed. The inherent peroxidase like activity of Fe7S8 NSs enables it to catalyze the oxidation of OPD in the existence of H2O2, resulting in the formation of yellow-colored 2, 3-diaminophenazine (DAP) with a characteristic absorption peak at 450 nm and a fluorescence emission peak at 560 nm. However, the presence of AA could suppress the oxidation of OPD and induce the generation of quinoxaline derivative (QXD) 3-(dihydroxyethyl) furo [3,4-b] quinoxaline-1-one with absorption and fluorescence emission peaks located at 345 and 435 nm, respectively. Thus, employing the absorption of QXD at 345 nm and emission at 435 nm as the reporting signals, and the absorption of DAP at 450 nm and emission at 560 nm as the reference signals, a ratio colorimetric (A345/A450) and ratio fluorescence (F435/F560) dual signal detection method for AA was developed. Under the optimized conditions, the value of A345/A450 was found to be linear with AA concentration in the ranges of 1.0–40 μM and 40–100 μM, and the value of F435/F560 was strongly correlated with AA concentration in the ranges of 1.0–30 μM and 30–100 μM. When applied for the assay of AA in human serum samples, an acceptable recovery ranging from 93.1 to 106.6 % was obtained, confirming the potential of the sensing system in practical applications.

Electrochemical hydrogen storage using SrFe12O19 surface-immobilized polyoxometalate

A tri-nickel substituted Keggin-type polyoxometalate (PMo9Ni3O37) was synthesized and subsequently immobilized on the surface of the M-type strontium hexaferrite (SrFe12O19) via the sol-gel method. The investigation of hydrogen storage capacity for the synthesized PMo9Ni3O37@SrFe12O19 nanocomposite was conducted through electrochemical methodologies employing chronopotentiometry (CP). A conventional three-electrode configuration employing copper foam coated with PMo9Ni3O37@SrFe12O19 served as the working electrode and was examined across a current range of ±1.5 mA. The charge and discharge of the experimental procedure indicated the substantial potential of the PMo9Ni3O37@SrFe12O19 nanocomposite in the hydrogen storage process, which was determined 3125 mAh/g during the discharge phase. The successful synthesis was corroborated thorough FT-IR, UV-vis, XRD, SEM, EDX, and BET surface area analysis techniques by examining the characteristic absorption wavelengths or reflection patterns. The size of the nanoparticles was determined through SEM analysis yielding a diameter of 36.76 nm, and using the Scherrer equation, a diameter of 29.22 nm was obtained.

Influence of fermentation with lactic bacteria on the structure, functional properties and antioxidant activity of flaxseed gum

Flaxseed meal is a by-product of flaxseed oil extraction. In this research, lactic acid bacteria suitable for modification of flaxseed gum were screened based on cellulase activity and the extraction rate of flaxseed gum. The enzyme-weight method was employed to extract flaxseed gum (SDF). The influences of fermentation modification on the extraction yield, structure, function, and antioxidant activity of flaxseed gum was investigated. Based on the enzyme-producing activity and extraction rate, Lactobacillus plantarum (LP-3), Bacillus paracaetocasei (KLDS-82), and Lactobacillus acidophilus (LAC-11) were identified as the most suitable strains for modifying flaxseed gum. The results indicated that the extraction yield of flaxseed gum was 18.45 % ± 0.2 % after fermentation with KLDS-82, which was significantly higher than that of the unmodified group. After fermentation, the microstructure of flaxseed gum became looser and more porous. The characteristic absorption peak of polysaccharide was observed through scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and X-ray diffraction (XRD), and the crystallization area was reduced. Simultaneously, its swelling capacity, water-holding capacity, oil-holding capacity, and other physicochemical properties have also been enhanced. The glucose adsorption capacity, cholesterol adsorption capacity, sodium cholic acid adsorption capacity, cation exchange capacity, α-glucosidase inhibitory activity, and antioxidant properties of SDF modified by Bacillus paracaetocasei (F-SDF) were significantly higher than those of Lactobacillus acidophilus modified SDF (S-SDF), Lactobacillus plantarum modified SDF (Z-SDF), and unmodified SDF (U-SDF). In conclusion, the modification effect of KLDS-82 is the most remarkable. Therefore, it can be utilized as a functional raw material in food.

Effect of TiO2 nanoparticles on the assembly of a copolymer-clay dispersion

Nanocomposites based on copolymer and clay minerals are attracting increasing attention as they are appropriate for extensive applications. In this work, we present results from an experimental study on the effects of TiO2 nanoparticles on a pluronic-F127/laponite water solution in the sol state. Differential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS) and Fourier Transform Infrared Attenuated Total Reflection Spectroscopy (FTIR-ATR) were used to characterize the systems. By DSC and DLS measurements the occurrence of micellization was first investigated. The temperature induced self-assembly was then studied by DLS identifying three relaxations associated to differently sized diffusing structures. The correlation between dynamics and bonding structure was thoroughly investigated by analyzing some specific infrared vibrational bands. In particular, the study of the characteristic absorption band of the ether groups in the dry state allowed to evaluate the amorphous/crystalline component evidencing the presence of more extended conformations in presence of the higher TiO2. Finally, the analysis of the bending mode for the residual water provided valuable insight about structural OH groups enabling a distinction between different types of water molecules associated to the copolymer/nanoparticle systems.