摘要:
Red-emissive carbon dots (CDs) were synthesized by one-step hydrothermal technique using citric acid (CA), and urea in N,N-dimethylformamide (DMF) solution. The CDs has an average diameter of 2.3 nm, excitation/emission maxima at 553/606 nm, and a low photoluminescence quantum yield (4%). Fluorescence is weakly quenched by the ions Fe(3+), Hg(2+), Cu(2+), Co(2+), Zn(2+), Ca(2+), Ni(2+), and Pb(2+). After addition of cetyltrimethyl ammonium ion (CTAB), electrostatic interaction between negatively charged CDs and CTAB causes the CDs to self-aggregate. The formation of CD/CTAB increases the average particle diameter to around 13 nm and enhances the quantum yield to 24%. The hydrophobic segments of CTAB twined into a network structure can selectively trap Fe(3+) and then interact with surface groups of the CDs to cause quenching. The CD/CTAB nanoprobe enables fluorometric determination of Fe(3+) with a linear response in the 0.10-10 muM concentration range and a 0.03 muM limit of detection. The probe was utilized for determination of Fe(3+) in human serum samples, and satisfactory results were obtained. Graphical abstractSchematic representation of fluorometric analysis of Fe(III) ion by cetyltrimethyl ammonium ion (CTAB) mediated red emission carbon dots (CDs). The hydrophobic segments of CTAB twined into a network structure can selectively trap Fe(III) and then interact with surface groups of the CDs to cause quenching.
期刊:
Particle & Particle Systems Characterization,2019年36(5):1800552- ISSN:0934-0866
通讯作者:
Lin, Qinlu;Chang, Huan-Tsung
作者机构:
[Xu, Dong; Lin, Qinlu] Cent South Univ Forestry & Technol, Coll Food Sci & Engn, Natl Engn Lab Rice & Byprod Further Proc, Changsha 410004, Hunan, Peoples R China.;[Xu, Dong; Lin, Qinlu] Cent South Univ Forestry & Technol, Hunan Key Lab Proc Food Special Med Purpose, Changsha 410004, Hunan, Peoples R China.;[Chang, Huan-Tsung] Natl Taiwan Univ, Dept Chem, Roosevelt Rd, Taipei 10617, Taiwan.;[Chang, Huan-Tsung] Chung Yuan Christian Univ, Dept Chem, Taoyuan 32023, Taiwan.
通讯机构:
[Lin, Qinlu; Chang, Huan-Tsung] C;[Chang, Huan-Tsung] N;Cent South Univ Forestry & Technol, Coll Food Sci & Engn, Natl Engn Lab Rice & Byprod Further Proc, Changsha 410004, Hunan, Peoples R China.;Cent South Univ Forestry & Technol, Hunan Key Lab Proc Food Special Med Purpose, Changsha 410004, Hunan, Peoples R China.;Natl Taiwan Univ, Dept Chem, Roosevelt Rd, Taipei 10617, Taiwan.
关键词:
absorption;chiral Ag and Au nanomaterials;circular dichroism;enantiomer recognition;fluorescence
摘要:
Abstract Sensing of chiral compounds has gained great attentions for many decades. Chiral nanomaterials with a greater surface area, optical properties, and stability have however not been well realized in this field. Herein, strategies for the preparation of chiral Ag and Au nanomaterials are focused upon, including Ag and Au nanoparticles conjugated with chiral molecules with/without containing fluorophores, chiral nanoassemblies of Ag and Au nanoparticles, and chiral Ag and Au nanoclusters. The chirality of nanomaterials originates from their core and/or ligand, meanwhile that for nanoassemblies results from their complex spatial configuration. An emphasis is given to circular dichroism, colorimetry/UV–vis absorption, and fluorescence detection modes for sensing enantiomers and achiral analytes using the chiral Ag and Au nanomaterials. Several interesting examples for quantitation of DNA, proteins, peptides, drugs, and pollutants are provided to highlight their potential as sensitive and selective nanomaterials for enantiomer recognition and sensing of achiral analytes. Several important issues to be solved when using chiral nanomaterials for chiral recognition are specified. Some strategies for improving the sensitivity and selectivity of chiral nanomaterials for chiral recognition are suggested. The aim is to bring more attention to the potential of chiral nanomaterials for sensing important analytes such as chiral drugs. Chiral Ag and Au nanomaterials have been gaining wide research attention in many fields. Their chirality can originate from ligands and/or metal core, spatial configurations in assembly and they are promising in enantiomer recognition and sensing. The optical sensors including circular dichroism, colorimetry/UV‐vis absorption and fluorescence for quantitation of small molecules, DNA, proteins, peptides, drugs and pollutants, are summarized.
摘要:
Native and acetylated broken-rice starches (nanocrystals) with different degrees of substitution (DS) and their corresponding films were individually prepared, and the drug release profiles, weight loss, solubility and dispersion and surface morphology were comparatively studied. Bovine serum albumin (BSA) was used as a model drug. Acetylated native starch (ANS) DS 2.58, acetylated starch nanocrystals (ASN) DS 0.98, ASN DS 1.86, and ASN DS 2.72 were observed to be very soluble in chloroform. BSA was released rapidly from the native rice starch (NS) and ANS DS 2.58 films. ASN with high DS significantly slowed down the release of BSA from films, the percentages of BSA released from film ASN DS 2.72 only reached to 13% after 3.5?weeks release, and the release data followed Korsmeyer-Peppas equation. Further studies reveal that the particle size of ASN DS 2.72 was smallest, and the weight loss of ASN DS 2.72 film was lowest. The results demonstrate that acetylation and nanometer particle form of rice starch film can effectively retard protein drug release, and the prepared films based on ASN with high DS from broken rice may be suitable for the controlled protein delivery. (C) 2019 Elsevier B.V. All rights reserved.
摘要:
In this work, the interaction of the soybean Bowman-Birk inhibitor (BBI) with stevioside (STE) was studied by stopped-flow-fluorescence and molecular docking. STE's inactivation of protease-inhibitor activities in soymilk and the influence of STE addition on the sensory character of soymilk were also evaluated. The results indicate that STE binds BBI with a binding constant ( Ka) of 3.38 x 10(5) L mol(-1) to form a 1:1 complex. The docking study reveals that two hydrogen bonds are formed between the side-chain of Lys16 (reactive site 1) of BBI and the glucose-ring hydroxyl groups of STE, which may block BBI from contacting trypsin and thus deactivate the trypsin-inhibitor activity (TIA) of BBI. Moreover, the residual TIA in soymilk could also be inactivated by STE. A mixture of 159 mg/L STE and 60 g/L sucrose could be used for sweetening soymilk without affecting the sensory characteristics when compared to a reference product sweetened with 9% sucrose.
摘要:
Lysosomal pH plays an essential role in mediating various biological processes such as immunization, cell metabolism and enzyme activity. Herein, by utilizing the fluorescence resonance energy transfer (FRET) strategy, a two-photon (TP) ratiometric fluorescent probe (NpLys-pH) has been developed for tracking of lysosomal pH changes in living cells, tissues, and zebrafish. NpLys-pH was constructed by conjugating a pH turn-on TP fluorophore 1 (D-p-A-structured naphthalene derivative) with a pH turn-off naphthalimide fluorophore 2 via a non-conjugated linker. Meanwhile, NpLys-pH has two potential pH response sites that modulate the fluorescence signal by ICT and PET, respectively. The FRET process exists between the TP fluorophore 1 and naphthalimide fluorophore 2. In addition, NpLys-pH respond to pH rapidly and reversibly with high selectivity and sensitivity and has been applied for tracking lysosomal pH changes in living cells, tissues and zebrafish. We expect that the new probe present here can prompt the development of a wide variety of TP ratiometric fluorescent probes which can find application in detecting other important analytes in biological systems.
摘要:
Nano-composite film possesses antibacterial properties of nanomaterials and preservation performance of food packaging film. The goal of this work was to explore the potential application of nano-silver-containing polyvinyl alcohol (PVA) composite film in grape fresh-keeping. Mechanical properties, transparency, barrier performance and antibacterial activity of Nano-silver-containing PVA film were tested and results showed that the antibacterial zone diameter of nano-silver on Aspergillus niger was 14.4 mm, with minimum bactericidal concentration of 75 ppm. The PVA antibacterial membrane effectively revealed antibacterial properties. Moreover, the decreased mechanical properties and transparency enhanced barrier performance of antibacterial membrane compared with PVA film. For comparison, the fresh-keeping effects of non-packaging film, commercial cling wrap and nano-silver-containing PVA film on sensory score, mass loss rate, decay rate, Ascorbic Acid (Vc) content and titratable acid content were also studied. Results indicated that the PVA antibacterial membrane significantly effectively avoided sensory score, water, decay, Ascorbic Acid (Vc) and titratable acid in grapes during storage, and had a remarkable effect in prolonging grapes' shelf life due to its breathability and antibacterial activity.
摘要:
Abstract A novel asparaginase (designated srnASNase) has been purified from soybean root nodules and identified by MALDI‐TOF/TOF‐MS. And the enzymatic properties, antitumor activity and the ability to prevent acrylamide formation in fried foods of srnASNase were evaluated. SrnASNase had high specific activity (531.37 U/mg) toward L‐asparagine under optimum conditions (pH 8.0 and 40°C), no activity toward L‐glutamine and D‐glutamine, but trace activity toward D‐asparagine. It was stable in the pH range of 7.0–9.0 and up to 40°C. The Km and Vmax of srnASNase were 0.36mM and 51.64mM/min, respectively. Further, in vitro anti‐proliferative activity on human cancer cells assay showed that srnASNase was superior to commercial asparaginase in solution by controlling the tumor cell growth with time. In addition, srnASNase showed more effective acrylamide mitigation than commercial asparaginase in fried foods. These results indicate that srnASNase is a potential candidate for applications in the food processing and pharmaceutical industry. Practical applications L‐asparaginase (L‐asparagine amidohydrolase; EC 3.5.1.1) is an enzyme that catalyzes the hydrolysis of the amide group of the side‐chain of L‐asparagine into aspartic acid and ammonia. It has long been used as a primary component in the treatment of acute lymphoblastic leukemia (All) and other related blood cancers. Apart from its clinical usage, L‐asparaginase has attracted more attention in the food processing industries as a promising acrylamide‐mitigating agent in recent years. This research revealed that soybean root nodules might be good sources of novel asparaginase. A novel asparaginase (srnASNase) has been purified and characterized from soybean root nodules. SrnASNase had good enzymatic properties. Further, srnASNase was superior to commercial asparaginase in solution by controlling the tumor cell growth with time. In addition, srnASNase showed more effective acrylamide mitigation than commercial asparaginase in fried foods. These results indicate that srnASNase is a potential candidate for applications in the food processing and pharmaceutical industry.
摘要:
MicroRNAs (miRNAs) may regulate diverse biological processes and play an important role in cancer. And MiRNAs have been proposed as a useful tool for lung cancer diagnosis and therapeutics in cancer. The purpose of the present study was to investigate the association among the expression level of mature miR-200b-5p in peripheral blood and the risk of lung cancer and clinic pathological characteristics. This case-control study included 24 patients with lung cancer and 12 healthy controls. MiR-200b expression was deleted using real-time PCR. and the miR-200b expression of normal controls was significantly higher than that in lung cancer patients (1732.13 pg/mL vs 881.67 pg/mL, P < 0.05), no difference with age, sex, tissue type and clinical stage of lung cancer patients (P > 0.05). Furthermore, miR-200b expression level fluctuated with tumor progression in lung cancer, and there was highly significant for clinical stage II compared with the clinical stage III (P < 0.05). In addition, the down-regulation of miR-200b showed a highly discriminative receiver operating characteristic (ROC) curve profile, clearly distinguishing cancer patients from cancer-free subjects with an area under the ROC curve (AUROC) of 0.87. The detection of miR-200b expression yielded 83.30% sensitivity and 100.00% specificity in the diagnosis of lung cancer. Therefore, these findings suggested that miR-200b may be used as a marker for the detection and diagnosis of lung cancer in peripheral blood. (C) 2018 Production and hosting by Elsevier B.V. on behalf of King Saud University.
摘要:
In this study, ultrasound was used to modulate the molecular structure of retrograded starch (RS3) responsible for the digestion properties, and the relationships among the ultrasonic power, molecular structure, and RS3 digestibility were revealed. Results revealed that the morphological characteristics of RS3 changed after ultrasonic treatment, and high power resulted in more compact block-shape structure. The results of particle size analysis, Fourier transform infrared spectroscopy, and X-ray diffraction showed that ultrasound decreased the long-range orders but increased the median particle size, short-range orders, and V-type polymorph of ultrasound-treated RS3. A decreased (double helix of amylopectin) and an increased (single helix of V-amylose) enthalpy change were observed by differential scanning calorimeter. Digestion profiles showed that some fractions of rapidly-digestible starch were converted into slowly-digestible starch and/or resistant starch. This study provides a potential approach to regulate the digestion of starch-rich foods with desired digestibility through ultrasonic treatment.
关键词:
Microwave and heat moisture treatment;Starch supramolecular structure;Physicochemical features
摘要:
From a supramolecular structure viewpoint, we concern how concurrent microwave and heat moisture treatment (M/HMT) tailors the pasting and digestion features of indica rice starch (IRS) and waxy rice starch (WRS), using combined analytical methods such as scanning electron microscopy and small-angle X-ray scattering. The results confirm that, for the starches (especially IRS), M/HMT led to a concave granule surface, weakened alignment of helices in lamellae, loosened packing of chains in amorphous regions, and somewhat disrupted crystallites. Consequently, the susceptibility of starch structures to hydrothermal effects was insignificantly altered, as reflected by unchanged pasting temperature; the enzyme absorption/hydrolysis could be properly accelerated, as affirmed by a modestly increased digestion rate and slightly reduced enzymatic resistance. Also, compared to WRS, IRS had more amylose with relatively long branches, which probably contributed to starch chain interactions during M/HMT. This tended to reduce the paste viscosity related to the swelling degree of starch granules, and increase the paste stabilities during heating and cooling related to the robustness of swelled granules and the reorganization of glucan chains. (C) 2019 Elsevier B.V. All rights reserved.