We report here the development of a rapid PCR microfluidic system comprising a double-shaft turntable and centrifugal-based disc that rapidly drives the PCR mixture between chambers set at different temperatures, and the bidirectional flow improved the space utilization of the disc. Three heating resistors and thermistors maintained uniform, specific temperatures for the denaturation, annealing, and extension steps of the PCR. Infrared imaging showed that there was little thermal interference between reaction chambers; the system enabled the cycle number and reaction time of each step to be independently adjusted. To validate the function and efficiency of the centrifugal microfluidic system, a 350-base pair target gene from the hepatitis B virus was amplified and quantitated by fluorescence detection. By optimizing the cycling parameters, the reaction time was reduced to 32 min as compared to 120 min for a commercial PCR machine. DNA samples with concentrations ranging from 10 to 10⁶ copies/mL could be quantitatively analyzed using this system. This centrifugal-based microfluidic platform is a useful system and possesses industrialization potential that can be used for portable diagnostics.

Uric acid (UA) is a kind of purine metabolism product and important in clinical diagnosis. In this work, we present a study of ZnS nanostructures-based electrochemical and photoelectrochemical biosensors for UA detection. Through a simple hydrothermal method and varying the ratio of reaction solvents, we obtained ZnS nanomaterials of one-dimensional to three-dimensional morphologies and they were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). To fabricate the UA biosensor and study the effect of material morphology on its performance, ZnS nanomaterials were deposited on indium tin oxide (ITO) conducting glass and then coated with uricase by physical absorption. Three kinds of working electrodes were characterized by cyclic voltammetry method. The effect of material morphology on performance of UA detection was investigated via amperometric response based electrochemical method based on enzymatic reaction. The ZnS urchin-like nanostructures electrode shows better sensitivity compared with those made of nanoparticles and nanoflakes because of its high surface-area-to-volume ratio. The photoelectrochemical method for detection of UA was also studied. The sensitivity was increased 5 times after irradiation of 300 nm UV light. These results indicate that ZnS nanostructures are good candidate materials for developing enzyme-based UA biosensors.

This study aimed to examine miR‐140 expression in clinical samples from tuberculosis (TB) patients and to explore the molecular mechanisms of miR‐140 in host‐bacterial interactions during Mycobacterium tuberculosis (M tb) infections. The miR‐140 expression and relevant mRNA expression were detected by quantitative real‐time PCR (qRT‐PCR); the protein expression levels were analysed by ELISA and western blot; M tb survival was measured by colony formation unit assay; potential interactions between miR‐140 and the 3′ untranslated region (UTR) of tumour necrosis factor receptor‐associated factor 6 (TRAF6) was confirmed by luciferase reporter assay. MiR‐140 was up‐regulated in the human peripheral blood mononuclear cells (PBMCs) from TB patients and in THP‐1 and U937 cells with M tb infection. Overexpression of miR‐140 promoted M tb survival; on the other hand, miR‐140 knockdown attenuated M tb survival. The pro‐inflammatory cytokines including interleukin 6, tumour necrosis‐α, interleukin‐1β and interferon‐γ were enhanced by M tb infection in THP‐1 and U937 cells. MiR‐140 overexpression reduced these pro‐inflammatory cytokines levels in THP‐1 and U937 cells with M tb infection; while knockdown of miR‐140 exerted the opposite actions. TRAF6 was identified to be a downstream target of miR‐140 and was negatively modulated by miR‐140. TRAF6 overexpression increased the pro‐inflammatory cytokines levels and partially restored the suppressive effects of miR‐140 overexpression on pro‐inflammatory cytokines levels in THP‐1 and U937 cells with M tb infection. In conclusion, our results implied that miR‐140 promoted M tb survival and reduced the pro‐inflammatory cytokines levels in macrophages with M tb infection partially via modulating TRAF6 expression.

Potassium permanganate (KMnO₄) is one of the most important oxidants, which plays important roles in many fields. Here, we found that KMnO₄ could directly induce the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to generate an oxidized product with a color change. This redox reaction is highly efficient, and 1 μM KMnO₄ is enough to cause detectable changes in the absorbance signal. Meanwhile, this reaction is very fast and the generated blue product can stabilize for a relatively long period, which has great advantages in practical applications. Since hydrogen peroxide (H₂O₂) is able to react with KMnO₄ under acidic conditions, the KMnO₄-TMB system can be used for the detection of H₂O₂; the absorbance signal induced by 5 μM H₂O₂ can be easily detected in this method. Meanwhile, the KMnO₄-TMB system can also be used for the detection of glucose by monitoring the generation of H₂O₂, which is the main product of glucose oxidation; this method permits detection of concentrations as low as 10 μM glucose, and the sensitivity is comparable to or higher than most peroxidase mimetic based methods, but avoiding the preparation and storage of the nanomaterials. Furthermore, the KMnO₄-TMB system can even be used for analyzing glucose in serum samples, which can also be expected to be used in immunoassays.

A MnO ₂ nanosheets– o -phenylenediamine (OPDA) oxidative system was developed for detecting ALP activity selectively, sensitively and conveniently.

In this work, we report a study of a zinc sulfide (ZnS) nanocrystal and reduced graphene oxide (RGO) nanocomposite-based non-enzymatic uric acid biosensor. ZnS nanocrystals with different morphologies were synthesized through a hydrothermal method, and both pure nanocrystals and related ZnS/RGO were characterized with SEM, XRD and an absorption spectrum and resistance test. It was found that compared to ZnS nanoparticles, the ZnS nanoflakes had stronger UV light absorption ability at the wavelength of 280 nm of UV light. The RGO significantly enhanced the electron transfer efficiency of the ZnS nanoflakes, which further led to a better photoelectrochemical property of the ZnS/RGO nanocomposites. The ZnS nanoflake/RGO nanocomposite-based biosensor showed an excellent uric acid detecting sensitivity of 534.5 μA·cm⁻²·mM⁻¹ in the linear range of 0.01 to 2 mM and a detection limit of 0.048 μM. These results will help to improve non-enzymatic biosensor properties for the rapid and accurate clinical detection of uric acid.