Characterization of a novel recombinant halophilic ß-glucosidase of Trichoderma harzianum derived from Hainan mangrove.

BACKGROUND: ß-glucosidase is an important biomass-degrading enzyme and plays a vital role in generating renewable biofuels through enzymatic saccharification. In this study, we analyzed the transcriptome of Trichoderma harzianum HTASA derived from Hainan mangrove and identified a new gene encoding ß-glucosidase Bgl3HB. And the biochemically characterization of ß-glucosidase activity was performed. RESULTS: Bgl3HB showed substantial catalytic activity in the pH range of 3.0-5.0 and at temperatures of 40 ℃-60 ℃. The enzyme was found quite stable at 50 ℃ with a loss of only 33.4% relative activity after 240 min of heat exposure. In addition, all tested metal ions were found to promote the enzyme activity. The ß-glucosidase activity of Bgl3HB was enhanced by 2.12-fold of its original activity in the presence of 5 M NaCl. Surprisingly, Bgl3HB also showed a remarkable ability to hydrolyze laminarin compared to other measured substrates. Enzyme efficiency was examined in the sugarcane bagasse saccharification processes, in which Bgl3HB with 5 M NaCl worked better supplementing Celluclast 1.5L than the commercial Novozyme 188 ascertained it as an admirably suited biocatalyst for the utilization of agricultural waste. In this work, this is the first report of a halophilic ß-glucosidase from Trichoderma harzianum, and represents the ß-glucosidase with the highest known NaCl activation concentration. And adding 5 M NaCl could enhance saccharification performance even better than commercial cellulase. CONCLUSIONS: These results show that Bgl3HB has great promise as a highly stable and highly efficient cellulase with important future applications in the industrial production of biofuels.

Indirect competitive assays on DVD for direct multiplex detection of drugs of abuse in oral fluids.

On-site oral fluid testing for drugs of abuse has become prominent in order to take immediate administrative action in an enforcement process. Herein, we report a DVD technology-based indirect competitive immunoassay platform for the quantitative detection of drugs of abuse. A microfluidic approach was adapted to prepare multiplex immunoassays on a standard DVD-R, an unmodified multimode DVD/Blu-Ray drive to read signal, and a free disc-quality analysis software program to process the data. The DVD assay platform was successfully demonstrated for the simultaneous, quantitative detection of drug candidates (morphine and cocaine) in oral fluids with high selectivity. The detection limit achieved was as low as 1.0 ppb for morphine and 5.0 ppb for cocaine, comparable with that of standard mass spectrometry and ELISA methods.

Urine multi-index intelligent detection based on polymer/paper hybrid microfluidic biochip for hyperuricemia monitoring.

Hyperuricemia (HUA) has gradually become a public health burden as an independent risk factor for a variety of chronic diseases. Herein, a user-friendly point-of-care (POC) detection system (namely "Smart-HUA-Monitor") based on smartphone-assisted paper-based microfluidic is proposed for colorimetric quantification of HUA urinary markers, including uric acid (UA), creatinine (CR) and pH. The detection limits of UA and CR were 0.0178 and 0.5983 mM, respectively, and the sensitivity of pH were 0.1. The method was successfully validated in artificial urine samples and 100 clinical samples. Bland-Altman plots showed a high consistency between µPAD and the testing instruments (HITACHI 7600 Automatic Analyzer, URIT-500B Urine Analyzer and AU5800B automatic biochemical analyzer) in hospital. Smart-HUA-Monitor provides an accurate quantitative, rapid, low-cost and reliable tool for the monitoring and early diagnosis of HUA urine indicators.

Flexible Strain Sensors Based on an Interlayer Synergistic Effect of Nanomaterials for Continuous and Noninvasive Blood Pressure Monitoring.

The continuous, noninvasive monitoring of human blood pressure (BP) through the accurate detection of pulse waves has extremely stringent requirements on the sensitivity and stability of flexible strain sensors. In this study, a new ultrasensitive flexible strain sensor based on the interlayer synergistic effect was fabricated through drop-casting and drying silver nanowires and graphene films on polydimethylsiloxane substrates and was further successfully applied for continuous monitoring of BP. This strain sensor exhibited ultrahigh sensitivity with a maximum gauge factor of 34357.2 (∼700% sensitivity enhancement over other major sensors), satisfactory response time (∼85 ms), wide strange range (12%), and excellent stability. An interlayer fracture mechanism was proposed to elucidate the working principle of the strain sensor. The real-time BP values can be obtained by analyzing the relationship between the BP and the pulse transit time. To verify our strain sensor for real-time BP monitoring, our strain sensor was compared with a conventional electrocardiogram-photoplethysmograph method and a commercial cuff-based device and showed similar measurement results to BP values from both methods, with only minor differences of 0.693, 0.073, and 0.566 mmHg in the systolic BP, diastolic BP, and mean arterial pressure, respectively. Furthermore, the reliability of the strain sensors was validated by testing 20 human subjects for more than 50 min. This ultrasensitive strain sensor provides a new pathway for continuous and noninvasive BP monitoring.

Effect of TiC Nanoparticles on a Zn-Al-Cu System for Biodegradable Cardiovascular Stent Applications.

Despite being a weaker metal, zinc has become an increasingly popular candidate for biodegradable implant applications due to its suitable corrosion rate and biocompatibility. Previous studies have experimented with various alloy elements to improve the overall mechanical performance of pure Zn without compromising the corrosion performance and biocompatibility; however, the thermal stability of biodegradable Zn alloys has not been widely studied. In this study, TiC nanoparticles were introduced for the first time to a Zn-Al-Cu system. After hot rolling, TiC nanoparticles were uniformly distributed in the Zn matrix and effectively enabled phase control during solidification. The Zn-Cu phase, which was elongated and sharp in the reference alloy, became globular in the nanocomposite. The strength of the alloy, after introducing TiC nanoparticles, increased by 31% from 259.7 to 340.3 MPa, while its ductility remained high at 49.2% elongation to failure. Fatigue performance also improved greatly by adding TiC nanoparticles, increasing the fatigue limit by 47.6% from 44.7 to 66 MPa. Furthermore, TiC nanoparticles displayed excellent phase control capability during body-temperature aging. Without TiC restriction, Zn-Cu phases evolved into dendritic morphologies, and the Al-rich eutectic grew thicker at grain boundaries. However, both Zn-Cu and Al-rich eutectic phases remained relatively unchanged in shape and size in the nanocomposite. A combination of exceptional tensile properties, improved fatigue performance, better long-term stability with a suitable corrosion rate, and excellent biocompatibility makes this new Zn-Al-Cu-TiC material a promising candidate for biodegradable stents and other biodegradable applications.

Abundant tannic acid modified gelatin/sodium alginate biocomposite hydrogels with high toughness, antifreezing, antioxidant and antibacterial properties.

The acidity of high tannic acid (TA) content solution can destroy the structure of protein, such as gelatin (G). This causes a big challenge to introduce abundant TA into the G-based hydrogels. Here, the G-based hydrogel system with abundant TA as hydrogen bonds provider was constructed by a "protective film" strategy. The protective film around the composite hydrogel was first formed by the chelation of sodium alginate (SA) and Ca2+. Subsequently, abundant TA and Ca2+ were successively introduced into the hydrogel system by immersing method. This strategy effectively protected the structure of the designed hydrogel. After treatment with 0.3 w/v TA and 0.06 w/v Ca2+ solutions, the tensile modulus, elongation at break and toughness of G/SA hydrogel increased about 4-, 2-, and 6-fold, respectively. Besides, G/SA-TA/Ca2+ hydrogels exhibited good water retention, anti-freezing, antioxidant, antibacterial properties and low hemolysis ratio. Cell experiments showed that G/SA-TA/Ca2+ hydrogels possessed good biocompatibility and could promote cell migration. Therefore, G/SA-TA/Ca2+ hydrogels are expected to be used in the field of biomedical engineering. The strategy proposed in this work also provides a new idea for improving the properties of other protein-based hydrogels.

Experimental study on novel biodegradable Zn-Fe-Si alloys.

Bioabsorbable metals are increasingly attracting attention for their potential use as materials for degradable implant devices. Zinc (Zn) alloys have shown great promises due to their good biocompatibility and favorable degradation rate. However, it has been difficult to maintain an appropriate balance among strength, ductility, biocompatibility, and corrosion rate for Zn alloys historically. In this study, the microstructure, chemical composition, mechanical properties, biocompatibility, and corrosion rate of a new ternary zinc-iron-silicon (Zn-Fe-Si) alloy system was studied as a novel material for potential biodegradable implant applications. The results demonstrated that the in situ formed Fe-Si intermetallic phases enhanced the mechanical strength of the material while maintaining a favorable ductility. With Fe-Si reinforcements, the microhardness of the Zn alloys was enhanced by up to 43%. The tensile strength was increased by up to 76% while elongation to failure remained above 30%. Indirect cytotoxicity testing showed the Zn-Fe-Si system had good biocompatibility. Immersion testing revealed the corrosion rate of Zn-Fe-Si system was not statistically different from pure Zn. To understand the underlying phase formation mechanism, the reaction process in this ternary system during the processing was also studied via phase evolution and Gibbs free energy analysis. The results suggest the Zn-Fe-Si ternary system is a promising new material for bioabsorbable metallic medical devices.

Effect of fabrication and processing technology on the biodegradability of magnesium nanocomposites.

Magnesium and its alloys have gained significant attention recently as potential alternatives for biodegradable materials due to their unique biodegradability, biocompatibility, and mechanical properties. However, magnesium alloys tend to have high corrosion rates in biological liquids, thus presenting a potential problem if a magnesium implant/device needs to maintain mechanical integrity for a sufficient period under practical physiological conditions. In this study, hydroxyapatite nanoparticles were used to form magnesium based metal matrix nanocomposites (MMNC) through two processes: friction stir processing (FSP) and a two-state nanoprocessing (TSnP) combining liquid state ultrasonic processing and solid state FSP. In addition, laser surface melting (LSM) was carried out for further surface treatment. In vitro immersion tests indicated that the corrosion rate of MMNC decreased by 52% compared with pure Mg through FSP. Potentiodynamic polarization tests showed that the corrosion current of MMNC decreased by 71% and 30%, respectively, by TSnP and LSM when compared with pure Mg or untreated counterparts. This study suggests that fabrication of MMNC and further processing through FSP and LSM can robustly enhance the corrosion resistance of magnesium, which will boost its potential for biological applications.