Rapid Signal Amplification Based on Planetary Cross-Catalytic Hairpin Assembly Reactions.

Non-enzymatic nucleic acid catalytic systems based on branch migration have been developed, with applications ranging from biological sensing to molecular computation. A scalable planetary cross-catalytic (PCC) system is built up in this work by cross-cascading three planetary catalytic hairpin assembly (CHA) reactions with a central three-arm-branched CHA reaction. With the bottom-up hierarchy strategy, we designed four levels of catalytic reactions, simple CHA reactions, two-layered linear cascades, conventional one-planetary PCC reactions, and two- and three-planetary PCC reactions, and examined the reaction products and intermediates in each level via native polyacrylamide gel electrophoresis. The gel shift assay optimized the designs of hairpin strands to keep the leaking reactions at a manageable level and protect against signal attenuation during serial signal transduction in nucleic acid circuits. The reaction kinetics, measured via fluorescence, are strongly dependent on the number of planetary reactions. As a result, the three-planetary PCC system achieved an exponential amplification factor of about 3k, while the conventional one-planetary cross-catalytic system has an amplification factor of 2k (k represents the cycling number). Finally, we demonstrated the rapid detection of a cancer biomarker, microRNA141, used as the catalyst in a two-planetary PCC system. We envision that the PCC systems could be applied in biological signal transduction, biocomputing, rapid detection of single- and multi-target nucleic acid probes, etc.

Mass tag-encoded nanointerfaces for multiplexed mass spectrometric analysis and imaging of biomolecules.

Revealing multiple biomolecules in the physiopathological environment simultaneously is crucial in biological and biomedical research. Mass spectrometry (MS) features unique technical advantages in multiplexed and label-free analyses. However, owing to comparably low abundance and poor ionization efficiency of target biomolecules, direct MS profiling of these biological species in vitro or in situ remains a challenge. An emerging route to solve this issue is to devise mass tag (MT)-encoded nanointerfaces which specifically convert the abundance or activity of biomolecules into amplified ion signals of mass tags, offering an ideal strategy for synchronous MS assaying and mapping of multiple targets in biofluids, cells and tissues. This review provides a thorough and organized overview of recent advances in MT-encoded nanointerfaces elaborately tailored for several practical applications in multiplexed MS bioanalysis and biomedical research. First, we start with elucidation of the structural characteristics and working principle of MT-encoded nanointerfaces in specific labeling and sensing of multiple biological targets. In addition, we further discuss the application scenarios of MT-encoded nanointerfaces particularly in multiplexed biomarker assays, cell analysis, and tissue imaging. Finally, the current challenges are pointed out and future prospects of these nanointerfaces in MS analysis are forecast.

Breastfeeding competency and its influencing factors among pregnant women in third trimester pregnancy: a cross-sectional study.

Competency is closely related to the occurrence of the behavior. Breastfeeding competence is the mastery of different breastfeeding factors which intervene in breastfeeding behavior. Breastfeeding competence could improve the breastfeeding behavior. However, few studies have paid attention to the status and the influencing factors of breastfeeding competency. The breastfeeding competency of pregnant women in third trimester pregnancy has the greatest impact on breastfeeding behavior after childbirth. Therefore, the objective of this study were to investigate the breastfeeding competency level and independent risk factors for breastfeeding competency among pregnant women in third trimester pregnancy. A cross-sectional survey method and convenience sampling method was used in the study. The general information questionnaire including age, gestational week, educational background, and so on were used to investigate the general information of pregnant women and their husbands. A breastfeeding competency scale (BCS) was used to investigate the breastfeeding competency of pregnant women. The total score of the BCS ranges from 38 to 190, with higher scores indicating greater breastfeeding competency. Lower level, medium level and higher level are 38-89, 90-140 and 141-190 respectively. Type-D Scale-14 (DS14) was used to investigate the type D personality of pregnant women. A multivariable linear regression was used to examine the independent predictors of breastfeeding competency. A total of 550 questionnaires were collected and finally 525 effective questionnaires were collected. The age of 525 pregnant women is (30.24 ± 3.954) years old. The breastfeeding competency score of pregnant women was (134 ± 19.741). Multivariable linear regression analysis showed that higher breastfeeding competency in pregnant women were reported among pregnant women who gestational age ≥ 256 days (37 weeks) (B = 8.494, p < 0.001), the previous breastfeeding experience were exclusive breastfeeding (B = 17.384, p < 0.001) and partial breastfeeding (B = 16.878, p < 0.001), participating in pregnant women school 2-3 times (B = 10.968, p = 0.013) and ≥ 5 times (B = 13.731, p = 0.034). Pregnant women with lower breastfeeding competency were found in women who were judged to have type D personality (B = - 6.358, p < 0.001). The result can explain 25.8% of the variation in the total breastfeeding competency score. This should be considered an important issue by maternal and child health care in the medical system that the moderate level of breastfeeding capacity among pregnant women. Differentiated and targeted breastfeeding support and services for pregnant women should be carried out based on influencing factors of breastfeeding competency.

Spatially Engineered Janus Hybrid Nanozyme toward SERS Liquid Biopsy at Nano/Microscales.

Nanomaterials with intrinsic enzyme-mimicking properties (nanozymes) have been widely considered as artificial enzymes in biomedicine. However, manipulating inorganic nanozymes for multivariant targeted bioanalysis is still challenging because of the insufficient catalytic efficiency and biological blocking effect. Here, we rationally designed a spatially engineered hollow Janus hybrid nanozyme vector (h-JHNzyme) based on the bifacial modulation of Ag-Au nanocages. The silver face inside the h-JHNzyme served as an interior gate to promote the enzymatic activity of the Ag-Au nanozyme, whereas two-dimensional DNAzyme-motif nanobrushes deposited on the exterior surface of the h-JHNzyme endowed it with the targeting function and tremendously enhanced the peroxidase-mimicking activity. We demonstrated that the spatially separated modulation of the h-JHNzyme propelled it as a powerful "all-in-one" enzymatic vector with excellent biocompatibility, specific vectorization, remarkable enzymatic performance, and clinical practicability. Further, we programmed it into a stringent catalytic surface-enhanced Raman scattering (SERS) liquid biopsy platform to trace multidimensional tumor-related biomarkers, such as microRNAs and circulating tumor cells, with a limit of detection of fM and single cell level, respectively. The developed enzymatic platform showed great potential in facilitating reliable quantitative SERS liquid biopsy for on-demand clinical diagnosis.

Concatenated Catalytic Hairpin Assembly/Hyperbranched Hybridization Chain Reaction Based Enzyme-Free Signal Amplification for the Sensitive Photoelectrochemical Detection of Human Telomerase RNA.

Human telomerase RNA (hTR), an important biomarker for cancer diagnosis, is the template for the synthesis of telomeric DNA repeats and is found to be 7-fold overexpressed in tumor cells. Herein, we present a photoelectrochemical (PEC) biosensor for hTR detection coupled with a novel amplification strategy based on cascades of catalytic hairpin assembly (CHA) and hyperbranched hybridization chain reaction (HB-HCR). At the electrode surface, thiolated hairpin 1 probes were immobilized on deposited CdS nanoparticles via a Cd-S bond. In the presence of target hTR, a CHA reaction was triggered and the exposing of trigger1 could further initiate an HB-HCR reaction to form abundant hemin/G-quadruplex DNAzymes containing dendritic DNA structure. The DNAzymes' catalytic precipitation of 4-chloro-1-naphthol (4-CN) by H2O2 subsequently took place on the surface of the PEC electrode and efficiently suppressed the photocurrent output. Therefore, the change of photocurrent response had a positive linear relationship with logarithmic value of hTR concentration varying from 200 fM to 20.0 nM with a limit of detection (LOD) of 17.0 fM. The LOD for CHA/HB-HCR was about 8.8-fold lower than that of CHA/linear-branched HCR (CHA/LB-HCR) and 547-fold lower than that of CHA. By coupling the feature of high signal amplification capacity for DNA nanotechnology, a prominently stable, reproducible, and selective PEC biosensor was successfully constructed and applied in hTR detection.

A competitive immunoassay for ultrasensitive detection of Hg(2+) in water, human serum and urine samples using immunochromatographic test based on surface-enhanced Raman scattering.

An immunochromatographic test (ICT) strip was developed for ultrasensitive competitive immunoassay of Hg(2+). This strategy was achieved by combining the easy-operation and rapidity of ICT with the high sensitivity of surface-enhanced Raman scattering (SERS). Monoclonal antibody (mAb) against Hg(2+) and Raman active substance 4-mercaptobenzoic acid (MBA) dual labelled gold nanoparticles (GNPs) were prepared as an immunoprobe. The Raman scattering intensity of MBA on the test line of the ICT strip was measured for quantitative determination of Hg(2+). The ICT was able to directly detect Hg(2+) without complexing due to the specific recognition of the mAb with Hg(2+). The IC50 and limit of detection (LOD) of the assay for Hg(2+) detection were 0.12 ng mL(-1) and 0.45 pg mL(-1), respectively. There was no cross-reactivity (CR) of the assay with other nineteen ions and the ICT strips could be kept for 5 weeks without loss of activity. The recoveries of the assay for water, human serum and urine samples spiked with Hg(2+) were in range of 88.3-107.3% with the relative standard deviations (RSD) of 1.5-9.5% (n = 3). The proposed ICT was used for the detection of Hg(2+) in urine samples collected from Occupational Disease Hospital and the results were confirmed by cold-vapor atomic fluorescence spectroscopy (CV-AFS). The assay exhibited high sensitivity, selectivity, stability, precision and accuracy, demonstrating a promising method for the detection of trace amount of Hg(2+) in environmental water samples and biological serum and urine samples.