Human serum albumin-mediated recognition of soluble amyloid-ß peptides using a time-resolved luminescent probe in plasma.

A terbium(iii) complex can recognize soluble Aß in plasma through human serum albumin (HSA)-mediated co-assembly, which can not only circumvent the interference of HSA, but also benefit Aß enrichment with amplified time-resolved luminescence enhancement.

A simple approach to quantitative determination of soluble amyloid-ß peptides using a ratiometric fluorescence probe.

Alzheimer's disease (AD) is a progressive neurodegenerative illness that affects the elderly population worldwide. The definite diagnosis of AD still depends on post-mortem pathological examination of amyloid plaques consisting of amyliod-ß peptides (Aß) fibrils in the brain so far. However, these fibrils are not closely linked to the development of the disease. Alternatively, soluble Aß are believed to be more reliable biomarkers for early diagnosis of AD. Here, we report a simple approach to quantitative detection of soluble Aß species using N-(6-(benzothiazol-2-yl)pyridin-3-yl)-5-(dimethylamino)naphthalene-1-sulfonamide (BPNS) as a ratiometric fluorescence Zn2+ probe. This ratiometric fluorescence assay is based on the competition of soluble Aß with BPNS for Zn2+, that is, soluble Aß species with higher chelation affinity can capture Zn2+ from BPNS‒Zn2+ adduct, thereby reactivating the ratiometric fluorescence response of BPNS. BPNS exhibited perfect linear relationship (R2 = 0.998) in accordance with the concentration of soluble Aß in the presence of Zn2+. The assay possesses strong anti-interference capacity against exogenous agent or the other proteins, thanks to the high selectivity for soluble Aß species. Importantly, this assay can quantitatively detect soluble Aß species from different types of biological fluids, such as artificial cerebrospinal fluid (ACSF), serum, and plasma in half an hour. This assay provides a low-cost, fast, sensitive, and simple approach for quantitative detection of soluble Aß species and may serve as a potential tool for early-stage AD diagnosis.

Dual Detection of Procalcitonin and C-reactive Protein with an Up-converting Nanoparticle Based Lateral Flow Assay.

Procalcitonin (PCT) and C-reactive protein (CRP) are significant complementary inflammatory markers, and their simultaneous detection is of substantial value. In this article, a rapid, simple and cost-effective method for the dual quantitative detection of PCT and CRP in serum is discussed. Two UCNPs of similar size and morphology, but with a different emission spectrum, were prepared for the simultaneous detection of PCT and CRP by lateral flow assay (LFA) technology in a direct method. With the developed dual test strips and signal read system, the assay results present a limit of detection (LOD) of 0.12 ng/mL and 0.24 µg/mL for PCT and CRP, respectively. In addition, both of the coefficients of variation and positive and negative concordance rates for PCT or CRP are well compared with those of the traditional method. The dual detection of PCT and CRP have shown great application potential in medical diagnosis and treatment guidance.

A rapid and user-friendly assay to detect the Neutrophil gelatinase-associated lipocalin (NGAL) using up-converting nanoparticles.

NGAL is a promising novel biomarker for acute kidney injury (AKI) and chronic kidney disease (CKD). More rapid and user-friendly methods are needed for the timely monitoring of NGAL in human urine and serum. UCP technology-based lateral flow assay (UPT-LFA) was developed for rapid, user-friendly and quantitative detection of the NGAL in human serum specimens and urine specimens. Under optimal conditions, the UPT-LFA displayed a rapid response to NGAL with a LOD of 7.68ng/mL and detection range from 7.68 to 1000ng/mL. The UPT-LFA method was compared with commercial immunoturbidimetry (103 urine specimens), and by ELISA (26 serum specimens), respectively. The results demonstrated that the UPT-LFA was consistent with immunoturbidimetry assay, reporting a 97.92% of positive and 92.73% of negative coincidence rates, respectively. Meanwhile, the concordance rate between UPT-LFA and ELISA, as shown by correlative regression analysis, was also high (R2=0.95). The whole assay can be completed within 30min compared to 4h consuming with ELISA. The research implies that, the UPT-LFA provides a potential to be used in point of care testing (POCT) to define early acute kidney injury with advantages of user-friendly and rapid testing, promising this new assay a bright future.

Preparation of K+-Doped Core-Shell NaYF4:Yb, Er Upconversion Nanoparticles and its Application for Fluorescence Immunochromatographic Assay of Human Procalcitonin.

In the present study, we reported a convenient route to prepare well dispersed and functionalized K+-doped core-shell upconversion nanoparticles (UCP) by layer-by-layer (LbL) assembly of polyelectrolytes. UCP was firstly transferred to aqueous phase using cationic surfactant cetyl trimethyl ammonium bromide (CTAB) via hydrophobic interaction without removing the existing oleic acid (OA). Then the positively charged hydrophilic UCP@CTAB was further alternately deposited with negatively charged [poly (sodium 4-styrenesulfonate)] (PSS), positively charged [poly (allylamine hydrochloride)] (PAH) and negatively charged [poly (acrylic acid)] (PAA). The final carboxyl functionalized UCP@CTAB@PSS@PAH@PAA was then conjugated with monoclonal antibody1 (AB1) of procalcitonin (PCT), resulting in successful detection of PCT antigens based on the immunochromatographic assay (ICA). Linear response was achieved from 0 to 10 ng/mL, and the lowest limit of detection (LLD) was 0.18 ng/mL.

Enhanced Sensitivity for Hydrogen Peroxide Detection: Polydiacetylene Vesicles with Phenylboronic Acid Head Group.

It was recently reported that, besides UV irradiated polymerization, polymerization of diacetylene compounds could also been initiated by radicals generated from enzyme catalyzed hydrogen peroxide (H2O2) decomposition. A new optical sensing method for H2O2 was proposed based on this phenomenon. However, the sensitivity of this method is relatively lower than existed ones. In the present work, phenylboronic acid (PBA) functionalized 10, 12-pentacosadiynoic acid (PDA-PBA) was synthesized and its vesicles were formed successfully as colorimetric sensor for H2O2 detection. It was found that color change during the polymerization of vesicles composed of the PBA modified monomer is much stronger than that of the non-modified one. The response of PDA-PBA vesicles to H2O2 is 16 times more sensitive than that of the PDA. The absorption of PDA-PBA at 650 nm is linearly related to the concentration of H2O2 and a detection limit of ~5 µM could be achieved.

Cell morphology variations of Klebsiella pneumoniae induced by acetate stress using biomimetic vesicle assay.

Supplementation with acetate under low levels was used as a novel approach to control the morphological development of Klebsiella pneumoniae aimed to improve 1,3-propanediol (1,3-PD) production. A full range of morphological types formed from rod shape to oval shape even round shape in response to different concentrations of acetate. The cell growth and 1,3-PD productions in the shake flasks with 0.5 g/L acetate addition were improved by 9.4 and 28.37%, respectively, as compared to the control, while the cell became shorter and began to lose its original shape. The cell membrane penetration by acetate was investigated by the biomimetic vesicles, while higher concentration of acetate led to more moderate colorimetric transitions. Moreover, the percentage composition of unsaturated fatty acid (UFA) was increased as well as the increased concentrations of acetate, whereas higher UFA percentage, higher fluidity of bacterial cell membrane.

Involvement of midkine expression in the inhibitory effects of low-frequency magnetic fields on cancer cells.

Effects of magnetic fields (MFs) on cancer cells may depend on cell type and exposure conditions. Gene expression levels are different among cancer cells. However, the effect of MFs on cancer cells with different gene expressions is still unclear. In this study, the cancer cell lines BGC-823, MKN-45, MKN-28, A549, SPC-A1, and LOVO were exposed to a low-frequency MF. Specific parameters of MFs were determined. Furthermore, the potential of the MF to influence cancer cell growth with midkine (MK) expression was evaluated. Cell proliferation and cell cycle were detected using the CCK-8 assay and flow cytometry. Cell ultrastructure was observed by transmission electron microscopy. BGC-823 cells with over-expression of MK (BGC-MK cells) and stanniocalcin-1 were generated by plasmid construction and transfection. Results showed that exposure to a 0.4-T, 7.5 Hz MF inhibited the proliferation of BGC-823, MKN-28, A549, and LOVO cells, but not MKN-45 and SPC-A1 cells. Moreover, the inhibitory effect of the MF on BGC-MK cells was lower (12.3%) than that of BGC-823 cells (20.3%). Analysis of the cell cycle showed that exposure to the MF led to a significant increase in the S phase in BGC-823 cells, but not in BGC-MK cells. In addition, organelle morphology was modified in BGC-823 cells exposed to the MF. These results suggest that exposure to a 0.4-T, 7.5 Hz MF could inhibit tumor cell proliferation and disturb the cell cycle. The alteration of MK expression in cancer cells may be related to the inhibitory effect of the MF on these cells.

Selective dehydration of bio-ethanol to ethylene catalyzed by lanthanum-phosphorous-modified HZSM-5: influence of the fusel.

Bio-ethanol dehydration to ethylene is an attractive alternative to oil-based ethylene. The influence of fusel, main byproducts in the fermentation process of bio-ethanol production, on the bio-ethanol dehydration should not be ignored. We studied the catalytic dehydration of bio-ethanol to ethylene over parent and modified HZSM-5 at 250°C, with weight hourly space velocity (WHSV) equal to 2.0/h. The influences of a series of fusel, such as isopropanol, isobutanol and isopentanol, on the ethanol dehydration over the catalysts were investigated. The 0.5%La-2%PHZSM-5 catalyst exhibited higher ethanol conversion (100%), ethylene selectivity (99%), and especially enhanced stability (more than 70 h) than the parent and other modified HZSM-5. We demonstrated that the introduction of lanthanum and phosphorous to HZSM-5 could weaken the negative influence of fusel on the formation of ethylene. The physicochemical properties of the catalysts were characterized by ammonia temperature-programmed desorption (NH(3)-TPD), nitrogen adsorption and thermogravimetry (TG)/differential thermogravimetry (DTG)/differential thermal analysis (DTA) (TG/DTG/DTA) techniques. The results indicated that the introduction of lanthanum and phosphorous to HZSM-5 could inhibit the formation of coking during the ethanol dehydration to ethylene in the presence of fusel. The development of an efficient catalyst is one of the key technologies for the industrialization of bio-ethylene.

1-(1,3-Benzodioxol-5-yl)pentan-1-one.

In the mol-ecule of title compound, C(12)H(14)O(3), the benzodioxole ring system is essentially planar. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into chains along the c axis, and π-π contacts between dioxole rings and between dioxole and benzene rings of the benzodioxole ring systems [centroid-centroid distances 3.702 (3) and 3.903 (3) Å] may further stabilize the structure. Two C-H⋯π inter-actions are also found.