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A multivalent DNA walker amplification biosensor combined with the microfluidic chip for simultaneously and sensitively detecting V.P, S.T, and S.A bacteria.

An exquisitely designed biomimetic multienzyme hybrid has been constructed by in situ encapsulating enzymes within a hierarchically porous bimetallic metal–organic framework.

The direct analysis of glycans by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) presents limited sensitivity due to the lower ionization efficiency of glycans. Various chemical derivatization methods have been developed to improve the detection sensitivity of glycans, but most of them need tedious preparation and cleanup procedures. Herein, a reactive matrix, 4-hydrazinoquinazoline (4-HQ), was developed for the rapid and sensitive detection of both neutral and sialylated glycans by MALDI MS. With 4-HQ as the reactive matrix, the detection limits of maltoheptaose and A3 glycan decreased 100-fold and 20-fold, respectively, compared with the conventional matrix. Moreover, 4-HQ formed homogeneous crystals and therefore showed good shot-to-shot reproducibility. Finally, the reactive matrix was successfully applied for the analysis of glycans released from glycoproteins and human serum. Importantly, the application of 4-HQ is the same as that of a conventional matrix with the additional advantage of on-target reaction at room temperature. Thus, 4-HQ can be used for the routine analysis of glycans by MALDI MS due to its simple use, great reproducibility, and enhanced detection of both neutral and sialylated glycans.

Tumor-derived exosomes, which contain RNA, DNA, and proteins, are a potentially rich non-invasive source of biomarkers. However, no efficient isolation or detection methods are yet available. Here, we developed a microfluidic Raman biochip designed to isolate and analyze exosomes in situ. Anti-CD63 magnetic nanoparticles were used to enrich exosomes through mixing channels of a staggered triangular pillar array. EpCAM-functionalized Raman-active polymeric nanomaterials (Raman beads) allow rapid analysis of exosome samples within 1 h, with a quantitative signal at 2230 cm-1. The limit of detection of this biochip approaches 1.6 × 102 particles per mL with 20 μL samples. The newly developed biochip assay was successfully applied in the determination of exosomes from clinical serum samples. Thus, this novel device may have potential as a clinical exosome analysis tool for prostate cancer.

Inorganic nanoparticle-based T1 contrast agents with high longitudinal relaxivity (r1) and low r2/r1 ratio have attracted great interest in recent years. However, the r1 relaxivity of inorganic nanoparticles reported to date is relatively low. In this work, 2.3 ± 0.1 nm paramagnetic gadolinium hydrated carbonate nanoparticles (GHC-1) with a high r1 relaxivity of 34.8 mM−1 s−1 and low r2/r1 ratio of 1.17 are synthesized using a one-pot hydrothermal process. The r1 of GHC-1 is 9.4 times higher than that of Gd-DTPA at 0.55 T. The synthetic procedure is simple, cost effective, and easy to scale up. The nanoparticles have a small core size, an amorphous phase, and are well-coated by poly(acrylic acid). Due to the hydrophilic polymer coating, the particles are highly dispersible and stable in aqueous solution. No significant cellular or in vivo toxicity are observed for the nanoparticles, which guarantees the in vivo application of this material. Finally, we apply the nanoparticles to in vivo magnetic resonance imaging and study the biodistribution in organs. This study reveals GHC-1 as a potential candidate for a T1 contrast agent with extraordinary ability to enhance MR images.

Novel superparamagnetic core-shell imprinting microspheres (MCSIMs) were synthesized using magnetite microspheres with 350 nm diameter and 70 nm thickness silica gel to form core-shell Fe(3)O(4)/SiO(2) composite for template phenylephrine (Phen) recognition and high efficiency separation. Compared to the previous imprinting recognition, the main advantage of this strategy lies in two aspects: one is the high stability and monodispersity of the MCSIMs structure, the other is the use of superparamagnetic Fe(3)O(4)/SiO(2) microspheres as an immobilization matrix and separation tool, thus greatly simplifying time-consuming washing steps. The affinity and selectivity of the MCSIMs were monitored by QCM and electrochemistry measurements. Imprinting microspheres have a remarkable affinity to Phen over that of structurally related molecules, including DA, EP, Phe and Tyr. The relative binding selectivity for different analytes estimated from amperometric signals was Phen : DA : EP = 40 : 5 : 1. The MCSIMs sensor showed a high sensitivity (400 microA mM(-1)), short response time (reaching 98% within 10 s), and broad linear response range from 1 microM to 0.1 mM and low detection limit (0.1 microM). Additionally, the results of control experiments showed that only negligible signal was obtained for non-imprinting microspheres. This could be reasonably attributed to the unique surface pores, charges and especially the nature of the functional groups inside MCSIMs cavities.