Structural characterization of inclusion complex of arbutin and hydroxypropyl-β-cyclodextrin

Purpose: To improve the solubility and stability of arbutin and to expand its application by preparing its inclusion complex with hydroxypropyl-β- cyclodextrin (HP-β-CD).Methods: An inclusion complex made of arbutin and hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared by freeze-drying method. Various analytical techniques, including ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), x-ray diffractometry (XRD) and thermo-gravimetric/differential scanning calorimetry (TG/DSC), were used to characterize the inclusion complex.Results: UV spectra indicated that no new unsaturated bond was formed in the inclusion complex. Infrared analysis showed that the smaller peaks in the proximity of 1450 - 1600 cm-1 were characteristic of the aromatic nucleus, indicating that the phenyl ring of arbutin was involved in the formation of the inclusion complex. Scanning electron micrographs of the inclusion complex showed that the original morphology of both components disappeared, and some tiny aggregates of amorphous areas of irregular size were present, revealing that the arbutin was dispersed in HP-β-CD. The powder XRD pattern of the inclusion complex was more similar to that of amorphous HP-β-CD and did not exhibit the characteristic peaks of arbutin which suggest that arbutin in HP-β-CD matrix was molecularly dispersed, and existed in an amorphous state. The TG curve of the inclusion complex was a one-step process, partly proving the formation of the complex. Complex formation with HP-β-CD remarkably improved the physical and chemical stabilities of arbutin.Conclusion: Inclusion complex of arbutin with HP-β-CD improves the heat stability of arbutin remarkably. This has a potential for expanding the application of arbutin to pharmaceuticals and food.Keywords: Arbutin, Hydroxypropyl-β-cyclodextrin, Inclusion complex, Physicochemical properties, Stability, Solubilit

Determination of cordycepin content of Cordyceps militaris recombinant rice by high performance liquid chromatography

Purpose: To assess the suitability of high performance liquid chromatography (HPLC) for the determination of cordycepin content of Cordyceps militaris recombinant riceMethods: Cordyceps militaris recombinant rice was made by mixing brown rice with artificial Chinese caterpillar fungus culture medium powder using twin-screw extrusion technology. Cordycepin content was determined by reversed-phase HPLC with water:acetonitrile (95:5, v/v) as mobile phase, detection wavelength of 260 nm, and flow rate of 1.0 mL/min.Results: Cordycepin contents showed good linearity in the range of 1 - 50.0 μg/mL (r2 = 0.9996), and while recovery ranged from 103.2 to 109.9 %. Relative standard deviation (RSD), precision and repeatability RSD was 2.38, 0.76 and 1.46 %, respectively.Conclusion: The HPLC method is simple, fast, accurate and reproducible. It is suitable for determination of cordycepin content of artificial Chinese caterpillar fungus culture medium and brown rice recombinant rice.Keywords: Recombinant rice, Cordycepin, Chinese caterpillar fungus, Aweto, Cordyceps militari

Inhibitory effect of α-cyclodextrin on α-amylase activity

Purpose: To explore the effect of α-cyclodextrin on the activity of α-amylase with a view to expanding its application range.Methods: The concentration of α-cyclodextrin, temperature, pH and interaction time were used as single factors to explore the influence of α-cyclodextrin on the activity of α-amylase and endogenous fluorescence in the enzyme system.Results: The results showed that the concentration, time, pH and temperature affect the interaction of them. The most obvious conditions for inhibition of α-amylase activity are as follows: 10 mmol/L concentration of α-cyclodextrin, pH 6.9, duration of 120 min and temperature at 55 oC. In addition, the fluorescence intensity of α-amylase changed as a result of the addition of α-cyclodextrin.Conclusion: The activity of α-amylase can be inhibited by α-cyclodextrin. At the same time, the addition of α-cyclodextrin will lead to the transfer of tryptophan group in α-amylase, which cause the change of microenvironment and changes the endogenous fluorescence intensity of α-amylase.Keywords: α-Cyclodextrin, α-Amylase, Fluorescence intensity, Inhibitio

Recognition of dipole-induced electric field in 2D materials for surface-enhanced Raman scattering

The application of two-dimensional (2D) materials, including metallic graphene, semiconducting transition metal dichalcogenides, and insulating hexagonal boron nitride (h-BN) for surface-enhancement Raman spectroscopy has attracted extensive research interest. This article provides a critical overview of the recent developments in surface-enhanced Raman spectroscopy using 2D materials. By re-examining the relationship between the lattice structure and Raman enhancement characteristics, including vibration selectivity and thickness dependence, we highlight the important role of dipoles in the chemical enhancement of 2D materials

Rs56288038 (C/G) in 3'UTR of IRF-1 Regulated by MiR-502-5p Promotes Gastric Cancer Development

Background/Aims: Interferon regulatory factor 1 (IRF-1) has been shown to function as a transcriptional activator or repressor of a variety of target genes. However, its upstream, non-coding RNA-related regulatory capacity remains unknown. In this study, we focus on the miRNA-associated single nucleotide polymorphisms (SNPs) in the 3′untranslated region (UTR) of IRF-1 to further investigate the functional relationship and potential diagnostic value of the SNPs and miRNAs among Chinese gastric cancer (GC) patients. Methods: We performed a case-control study with 819 GC patients and 756 cancer-free controls. Genotyping by realtime PCR assay, cell transfection, and the dual luciferase reporter assay were used in our study, and the 5-year overall survival rate and relapse-free survival rate in different groups were investigated. Results: We found that patients suffering from Helicobacter pylori (Hp) infection were the susceptible population compared to controls. SNP rs56288038 (C/G) in IRF-1 3′UTR was involved in the occurrence of GC by acting as a tumor promoter factor. SNP rs56288038 (C/G) could be up-regulated by miR-502-5p, which caused a down-regulation of IRF-1 in cell lines and decreased apoptosis induced by IFN-γ. Carrying the G genotype was related to significantly low expression of IRF-1 and Hp infection, poor differentiation, big tumor size, invasion depth, as well as the high probability of metastasis, and moreover, the C/G SNP was associated with shorter survival of GC patients with five years of follow-up study. Conclusions: our findings have shown that the SNP rs56288038 (C/G) in IRF-1 3′UTR acted as a promotion factor in GC development through enhancing the regulatory role of miR-502-5p in IRF-1 expression

Morphology and Rheology of a Cool-Gel (Protein) Blended with a Thermo-Gel (Hydroxypropyl Methylcellulose)

This study investigates the morphological and rheological properties of blended gelatin (GA; a cooling-induced gel (cool-gel)) and hydroxypropyl methylcellulose (HPMC; a heating-induced gel (thermo-gel)) systems using a fluorescence microscope, small angle X-ray scattering (SAXS), and a rheometer. The results clearly indicate that the two biopolymers are immiscible and have low compatibility. Moreover, the rheological behavior and morphology of the GA/HPMC blends significantly depend on the blending ratio and concentration. Higher polysaccharide contents decrease the gelling temperature and improve the gel viscoelasticity character of GA/HPMC blended gels. The SAXS results reveal that the correlation length (ξ) of the blended gels decreases from 5.16 to 1.89 nm as the HPMC concentration increases from 1 to 6%, which suggests that much denser networks are formed in blended gels with higher HPMC concentrations. Overall, the data reported herein indicate that the gel properties of gelatin can be enhanced by blending with a heating-induced gel

Structural Transitions of Alpha-Amylase Treated with Pulsed Electric Fields: Effect of Coexisting Carrageenan

Pulsed electric field (PEF) is an effective way to modulate the structure and activity of enzymes; however, the dynamic changes in enzyme structure during this process, especially the intermediate state, remain unclear. In this study, the molten globule (MG) state of α-amylase under PEF processing was investigated using intrinsic fluorescence, surface hydrophobicity, circular dichroism, etc. Meanwhile, the influence of coexisting carrageenan on the structural transition of α-amylase during PEF processing was evaluated. When the electric field strength was 20 kV/cm, α-amylase showed the unique characteristics of an MG state, which retained the secondary structure, changed the tertiary structure, and increased surface hydrophobicity (from 240 to 640). The addition of carrageenan effectively protected the enzyme activity of α-amylase during PEF treatment. When the mixed ratio of α-amylase to carrageenan was 10:1, they formed electrostatic complexes with a size of ~20 nm, and carrageenan inhibited the increase in surface hydrophobicity (<600) and aggregation (<40 nm) of α-amylase after five cycles of PEF treatment. This work clarifies the influence of co-existing polysaccharides on the intermediate state of proteins during PEF treatment and provides a strategy to modulate protein structure by adding polysaccharides during food processing

Temperature Effect of Nano-Structure Rebuilding on Removal of DWS mc-Si Marks by Ag/Cu MACE Process and Solar Cell

The absence of an effective texturing technique for diamond-wire sawn multi-crystalline silicon (DWS mc-Si) solar cells has hindered commercial upgrading from traditional multi-wire slurry sawn silicon (MWSS mc-Si) solar cells. In this work, we present a novel method for the removal of diamond-wire-sawn marks in a multi-crystalline silicon wafer based on metal assisted chemical etching process with Cu/Ag dual elements and nano-structure rebuilding (NSR) treatment to make a uniform inverted pyramid textured structure. The temperature effect of NSR solution was systematically analyzed. It was found that the size of the inverted pyramid structure and the reflectance became larger with the increase of the NSR treatment temperature. Furthermore, the prepared unique inverted pyramid structure not only benefited light trapping, but also effectively removed the saw-marks of the wafer at the same time. The highest efficiency of 19.77% was obtained in solar cells with an inverted pyramid structure (edge length of 600 nm) fabricated by NSR treatment at 50 °C for 360 s, while its average reflectance was 16.50% at a 400–900 nm wavelength range