An amperometric bienzymatic biosensor for the triglyceride tributyrin using an indium tin oxide electrode coated with electrophoretically deposited chitosan-wrapped nanozirconia

A lipase-conjugated carbon nanotube fiber-optic SPR sensor for sensitive and specific detection of tributyrin

As a low-density lipoprotein, tributyrin plays an essential role in food safety and human health. In this study, a novel lipase-conjugated carbon nanotube (CNT) surface plasmon resonance (SPR) fiber-optic sensor is used to specifically detect tributyrin for the first time. In this work, CNTs can be used as an amplifying material to significantly increase the sensitivity of SPR sensors due to their high refractive index and large surface area. CNTs can also be used as an enzyme carrier to provide abundant carboxyl groups for the specific binding of lipases. Covering the surface of the sensor with CNTs can not only enhance the performance of the sensor, but also provide sufficient detection sites for subsequent biomass detection, reduce the functionalization steps, and simplify the sensor preparation process. The experimental results demonstrate that the refractive index sensitivity of the traditional multimode fiber (MMF)-single mode fiber (SMF)-MMF transmissive optical fiber sensor is 1705 nm RIU-1. After covering the sensor with CNTs, the sensitivity is 2077 nm RIU-1, and the sensitivity has been improved very well. In addition, there are abundant functional groups on CNTs, which can provide abundant binding sites. Conjugating lipase on carbon nanotubes helps to achieve linear detection in the range of 0.5 mM to 4 mM tributyrin, with a sensitivity of 4.45 nm mM-1 and a detection limit of 0.34 mM, which is below the 2.26 mM detection standard and meets food safety monitoring requirements. Compared with other sensors, the optical fiber biosensor proposed in this study expands the concentration detection range of tributyrin. Furthermore, the sensor also has good stability, anti-interference performance and specificity. Therefore, the sensor proposed in this paper has good application prospects in the fields of food safety and biomedicine.

Triglyceride-Tethered Membrane Lipase Sensor

Sensors that can quickly measure the lipase activity from biological samples are useful in enzyme production and medical diagnostics. However, current lipase sensors have limitations such as requiring fluorescent labels, pH control of buffer vehicles, or lengthy assay preparation. We introduce a sparsely tethered triglyceride substrate anchored off of a gold electrode for the impedance sensing of real-time lipase activity. The tethered substrate is self-assembled using a rapid solvent exchange technique and can form an anchored bilayer 1 nm off the gold electrode. This allows for an aqueous reservoir region, providing access to ions transported through membrane defects caused by triglyceride enzymatic hydrolysis. Electrical impedance spectroscopy techniques can readily detect the decrease in resistance caused by enzymatically induced defects. This rapid and reliable lipase detection method can have potential applications in disease studies, monitoring of lipase production, and as point-of-care diagnostic devices.

Application of nanotechnology in the diagnosis and treatment of acute pancreatitis

Acute pancreatitis (AP) is a common digestive system disease. The severity of AP ranges from mild edema in the pancreas to severe systemic inflammatory responses leading to peripancreatic/pancreatic necrosis, multi-organ failure and death. Improving the sensitivity of AP diagnosis and developing alternatives to traditional methods to treat AP have gained the attention of researchers. With the continuous rise of nanotechnology, it is being widely used in daily life, biomedicine, chemical energy and many other fields. Studies have demonstrated the effectiveness of nanotechnology in the diagnosis and treatment of AP. Nanotechnology has the advantages of simplicity, rapidity and sensitivity in detecting biomarkers of AP, as well as enhancing imaging, which helps in the early diagnosis of AP. On the other hand, nanoparticles (NPs) have oxidative stress inhibiting and anti-inflammatory effects, and can also be loaded with drugs as well as being used in anti-infection therapy, providing a new approach for the treatment of AP. In this article, we elaborate and summarize on the potential of nanoparticles for diagnostic and therapeutic applications in AP from the current reported literature and experimental results to provide useful guidelines for further research on the application of nanotechnology.

Different strategies for the lipase immobilization on the chitosan based supports and their applications

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Facile fabrication of chitosan-based adsorbents for effective removal of cationic and anionic dyes from aqueous solutions

To develop chitosan-based adsorbents for the treatment of dye wastewater, poly acrylic acid (PAA) and poly acrylamide (PAM) were simultaneously grafted onto the chitosan (CTS) chain to obtain a grafted-crosslinked material g-CCTS, and then, Fe-g-CCTS was prepared via coordination of Fe(III) onto the prepared g-CCTS. Two adsorbents g-CCTS and Fe-g-CCTS were fully characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Nitrogen adsorption and desorption, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis. In adsorption experiment, g-CCTS exhibited effective adsorption towards cationic dye methylene blue (MB), and Fe-g-CCTS showed effective adsorption towards anionic dye reactive brilliant red (RBR). The effects of solution pH, salt concentration and temperature on the adsorption process were investigated. The maximum adsorption capacity of g-CCTS for MB was up to 79.09 mg/g at pH 12, and that of Fe-g-CCTS for RBR reached 918.53 mg/g at pH 2. It was observed that both adsorption processes were monolayer adsorption, and conformed to the pseudo-second-order model and the Langmuir isotherm model. This research provided a facile and accurate method for effective dyes removal from wastewater.

Electrodeposition of Polysaccharide and Protein Hydrogels for Biomedical Applications

In the last few decades, polysaccharide and protein hydrogels have attracted significant attentions and been applied in various engineering fields. Polysaccharide and protein hydrogels with appealing physical and biological features have been produced to meet different biomedical applications for their excellent properties related to biodegradability, biocompatibility, nontoxicity, and stimuli responsiveness. Numerous methods, such as chemical crosslinking, photo crosslinking, graft polymerization, hydrophobic interaction, polyelectrolyte complexation and electrodeposition have been employed to prepare polysaccharide and protein hydrogels. Electrodeposition is a facile way to produce different polysaccharide and protein hydrogels with the advantages of temporal and spatial controllability. This paper reviews the recent progress in the electrodeposition of different polysaccharide and protein hydrogels. The strategies of pH induced assembly, Ca2+ crosslinking, metal ions induced assembly, oxidation induced assembly derived from electrochemical methods were discussed. Pure, binary blend and ternary blend polysaccharide and protein hydrogels with multiple functionalities prepared by electrodeposition were summarized. In addition, we have reviewed the applications of these hydrogels in drug delivery, tissue engineering and wound dressing.

Biofunctionalized Nanostructured Yttria Modified Non-Invasive Impedometric Biosensor for Efficient Detection of Oral Cancer

We report results of the studies relating to the development of an efficient biosensor for non-invasive detection of CYFRA-21-1 cancer biomarker. We used a low dielectric constant material (nanostructured yttrium oxide, nY2O3) for the fabrication of the biosensing platform. The nY2O3 was synthesized via solvothermal process and functionalized using 3-aminopropyl triethoxy silane (APTES). Electrophoretic deposition (EPD) of the functionalized nanomaterial (APTES/nY2O3) onto an indium tin oxide (ITO)-coated glass electrode was conducted at a DC potential of 50V for 60s. The EDC-NHS chemistry was used for covalent immobilization of -COOH bearing monoclonal anti-CYFRA-21-1 onto -NH2 groups of APTES/nY2O3/ITO electrode. To avoid the non-specific interaction on the anti-CYFRA-21-1/APTES/nY2O3/ITO immunoelectrode, bovine serum albumin (BSA) was used. X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were utilized for structural and morphological studies, whereas Fourier-transform infrared spectroscopy (FTIR) was used for the bonding analysis. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used for electrochemical characterization and response studies of fabricated electrodes. The fabricated immunosensor (BSA/anti-CYFRA-21-1/APTES/nY2O3/ITO) exhibited linearity in the range of 0.01-50 ng·mL-1, sensitivity of 226.0 Ω·mL·ng-1, and lower detection limit of 0.01·ng·mL-1. A reasonable correlation was observed between the results obtained using this biosensor and concentration of CYFRA-21-1 measured through ELISA (enzyme-linked immunosorbent assay) technique in salivary samples of oral cancer patients.

Recent advances in designing nanomaterial based biointerfaces for electrochemical biosensing cardiovascular biomarkers

Early diagnosis of cardiovascular disease (CVD) is critically important for successful treatment and recovery of patients. At present, detection of CVD at early stages of its progression becomes a major issue for world health. The nanoscale electrochemical biosensors exhibit diverse outstanding properties, rendering them extremely suitable for the determination of CVD biomarkers at very low concentrations in biological fluids. The unique advantages offered by electrochemical biosensors in terms of sensitivity and stability imparted by nanostructuring the electrode surface together with high affinity and selectivity of bioreceptors have led to the development of new electrochemical biosensing strategies that have introduced as interesting alternatives to conventional methodologies for clinical diagnostics of CVD. This review provides an updated overview of selected examples during the period 2005-2018 involving electrochemical biosensing approaches and signal amplification strategies based on nanomaterials, which have been applied for determination of CVD biomarkers. The studied CVD biomarkers include AXL receptor tyrosine kinase, apolipoproteins, cholesterol, C-reactive protein (CRP), D-dimer, fibrinogen (Fib), glucose, insulin, interleukins, lipoproteins, myoglobin, N-terminal pro-B-type natriuretic peptide (BNP), tumor necrosis factor alpha (TNF-α) and troponins (Tns) on electrochemical transduction format. Identification of new specific CVD biomarkers, multiplex bioassay for the simultaneous determination of biomarkers, emergence of microfluidic biosensors, real-time analysis of biomarkers and point of care validation with high sensitivity and selectivity are the major challenges for future research.

Lipase, Phospholipase, and Esterase Biosensors (Review)

A biosensor is a device composed by a biological recognition element and a transducer that delivers selective information about a specific analyte. Technological and scientific advances in the area of biology, bioengineering, catalysts, electrochemistry, nanomaterials, microelectronics, and microfluidics have improved the design and performance of better biosensors. Enzymatic biosensors based on lipases, esterases, and phospholipases are valuable analytical apparatus which have been applied in food industry, oleochemical industry, biodegradable polymers, environmental science, and overall the medical area as diagnostic tools to detect cholesterol and triglyceride levels in blood samples. This chapter reviews recent developments and applications of lipase-, esterase-, and phospholipase-based biosensors.

Efficient removal and environmentally benign detoxification of Cr(VI) in aqueous solutions by Zr(IV) cross-linking chitosan magnetic microspheres

Zirconium(IV) cross-linking chitosan (CTS) magnetic microspheres (Fe₃O₄@Zr-CTS) as a recoverable adsorbent were synthesized through the coordination reaction between zirconium oxychloride and CTS biopolymeric matrix for efficient adsorption and simultaneous detoxification of hexavalent chromium, Cr(VI), in aqueous solutions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the formation of core@shell magnetite microspheres. X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) verified the crosslinking of Zr(IV) to CTS on the microspheres. Batch Cr(VI) adsorption performances of the resultant Fe₃O₄@Zr-CTS microspheres revealed that the maximum adsorption capacity of 280.97 mg/g were achieved under pH 4.0 at 298 K. The XPS analyses indicated that 61.1% of the adsorbed Cr(VI) was reduced to Cr(III) due to the oxidization of alcoholic groups on C-6 in CTS which served as electron donors to carbonyl groups. The adsorbent showed preferential Cr(VI) adsorption with the existence of co-existing cations (K⁺, Na⁺, Cu²⁺, Zn²⁺, Ca²⁺, Mg²⁺) and anions (NO₃^-, Cl^-, SO₄^2-, CO₃^2-). The adsorbent exhibited excellent reusability, lower the effluent Cr(VI) contents down to the ppb level, which satisfied the drinking water standard recommended by the World Health Organization and was a promising candidate for water purification.