Construction of triglyceride biosensor based on nickel oxide–chitosan/zinc oxide/zinc hexacyanoferrate film

Recent Advances in Applications of Oxidases and Peroxidases Polymer-Based Enzyme Biocatalysts in Sensing and Wastewater Treatment: A Review

Oxidase and peroxidase enzymes have attracted attention in various biotechnological industries due to their ease of synthesis, wide range of applications, and operation under mild conditions. Their applicability, however, is limited by their poor stability in harsher conditions and their non-reusability. As a result, several approaches such as enzyme engineering, medium engineering, and enzyme immobilization have been used to improve the enzyme properties. Several materials have been used as supports for these enzymes to increase their stability and reusability. This review focusses on the immobilization of oxidase and peroxidase enzymes on metal and metal oxide nanoparticle-polymer composite supports and the different methods used to achieve the immobilization. The application of the enzyme-metal/metal oxide-polymer biocatalysts in biosensing of hydrogen peroxide, glucose, pesticides, and herbicides as well as blood components such as cholesterol, urea, dopamine, and xanthine have been extensively reviewed. The application of the biocatalysts in wastewater treatment through degradation of dyes, pesticides, and other organic compounds has also been discussed.

Polymeric Nanocomposites for Environmental and Industrial Applications

Polymeric nanocomposites (PNC) have an outstanding potential for various applications as the integrated structure of the PNCs exhibits properties that none of its component materials individually possess. Moreover, it is possible to fabricate PNCs into desired shapes and sizes, which would enable controlling their properties, such as their surface area, magnetic behavior, optical properties, and catalytic activity. The low cost and light weight of PNCs have further contributed to their potential in various environmental and industrial applications. Stimuli-responsive nanocomposites are a subgroup of PNCs having a minimum of one promising chemical and physical property that may be controlled by or follow a stimulus response. Such outstanding properties and behaviors have extended the scope of application of these nanocomposites. The present review discusses the various methods of preparation available for PNCs, including in situ synthesis, solution mixing, melt blending, and electrospinning. In addition, various environmental and industrial applications of PNCs, including those in the fields of water treatment, electromagnetic shielding in aerospace applications, sensor devices, and food packaging, are outlined.

Dual-fiber optic bioprobe system for triglyceride detection using surface plasmon resonance sensing and lipase-immobilized magnetic bead hydrolysis

The rapid and accurate detection of triglyceride (TG) plays a valuable role in the prevention and control of dyslipidemia. In this paper, a novel method for TG detection using a dual-fiber optic bioprobe system, which can accurately detect different levels of TG concentration in serum, is proposed. The system employs disposable microprobe-type fiber optic surface plasmon resonance (SPR) biosensors for signal acquisition, providing high stability and portability while avoiding cross-contamination caused by repeated use. The proposed biosensor with a high sensitivity of 1.25 nm/(mg/mL) for TG detection in serum and a tiny diameter of 125 μm, was fabricated using a novel multimode fiber-single-mode fiber-reflector (MSR) structure, which has been scarcely ever reported to the best of our knowledge. In the process of TG detection, lipase-immobilized magnetic beads were introduced to specifically hydrolyze TG, and the relationship between the TG content and the SPR differential signal was obtained from dual-fiber optic bioprobe measurements of the TG sample before and after hydrolysis. The proposed method achieved TG detection in the concentration range of 0-8 mg/mL (including healthy and unhealthy levels of TG concentration in the human body). Additionally, the miniaturized fiber optic biosensors used in this work have the advantages of low sample consumption, high sensitivity, simple operation, label-free measurement, high selectivity, and low cost. This method provides a new pathway for rapid and reliable TG detection and has potential applications in medical research and clinical diagnosis.

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.

Organic Polymer and Metal Nano-particle Based Composites for Improvement of the Analytical Performance of Electrochemical Biosensors

Metal nanoparticles (NPs) are described in the nanoscale and made from either pure metals or their compounds such as oxides. Metallic NPs have certain indistinct functional groups due to which these can bind with any type of ligand, antibody and drugs. Organic polymers, which conduct electricity, are called conducting polymers (intrinsically conducting polymers). They behave like semiconductors by exhibiting metallic conductivity. Process-ability is the major advantage of conducting polymers. Nanocomposite is a novel material having nano-fillers scattered in a matrix with morphology and interfacial characteristics of nano-composites including their individual property that influence their characteristics. Conducting polymers and NP composites can enhance the rate of electron transport between the current collector material (electrode) and the electrolyte; therefore they have been employed in the construction of improved electrochemical sensors such as amperometric, catalytic and potentiodynamic affinity sensors.

Performance of chitosan polymer as platform during sensors fabrication and sensing applications

Chitosan is an important polymer produced from deacetylation of several sea and insects crusts. Due to its environmental fate and biological biocompatibility, it can be used in several biological and environmental applications. Sensing of biological compounds in human bodies and also in serum, blood, and different body fluids has found an important application instead of direct determination of the body fluids using complicated tools. Sensing process of biological compounds during bio-analysis of the biological systems, especially human fluids lack of several parameters including: high sensitivity, repeatability, speed of analysis and biocompatibility of the used analytical methods, especially in-vivo analysis. That was due to the time between sample handling and sample determination can change various components and concentrations of the bio-compounds. The need for in-situ analysis was directed the researchers for biosensors to overcome the upgrading problems of bio-analysis. Biosensors were the future of this issue. Chitosan can reserve as great platform for fabrication of different sensors to determine the elements, compounds and body bioactive compounds. The presence of different terminal amino and hydroxyl groups within chitosan framework facilitates the immobilization of different biomarkers to be used as sensing elements for the determined compounds. The use of chitosan as sensors platform was enhanced by using chitosan in its nanoforms.

Construction of a Hydrogel Pectin-Based Triglyceride Optical Biosensor with Immobilized Lipase Enzymes

A novel and simple optical biosensor to detect triglycerides (TGs) has been successfully constructed by using pectin hydrogel membrane as the indicator pH and chromoionophore ETH 5294 (CI), with lipase as the catalyst. The enzymatic working system against TGs releasing H⁺ ions will affect the color absorbance of CI. The characterization results show that a TG biosensor has the optimum condition and sensitivity at the phosphate buffer concentration of 50 mM, pH 7, and enzyme loading of 60 μg. The biosensor works at the tripalmitin (TP) concentration range of 100–400 mg/dL. With the sensitivity of 0.001 (∆A/(mg/dL)), the biosensor response reaches stability after five minutes, and the limit of detection (LOD) of the TG optical biosensor is 15 mg/dL. Relative standard deviation (RSD) in a reproducibility test was 2.5%, with a 15-day lifespan.

A highly sensitive biosensor based on Au NPs/rGO-PAMAM-Fc nanomaterials for detection of cholesterol

Objective

This study aimed to construct a biosensor using Au nanoparticles (Au NPs) and reduced graphene-polyamide-amine-ferrocene (rGO-PAMAM-Fc) nanomaterials designed for rapid and sensitive detection of cholesterol.

Materials and methods

In this study, a highly sensitive biosensor based on Au NPs/ rGO-PAMAM-Fc nanomaterials was manufactured for detection of cholesterol. The rGO-PAMAM-Fc and Au NPs were modified on the surface of the electrode and then coated with cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) to develop the ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor.

Results

The capability of rGO-PAMAM-Fc nanomaterials in fabricating a more efficient biosensor was validated through stability, selectivity and reproducibility checks. Under optimal conditions, the newly developed biosensor showed a linear relationship with logarithm of cholesterol concentration from 0.0004 to 15.36 mM (R²=0.9986), and a low detection limit of 2 nM was obtained at the signal/noise ratio of 3.

Conclusion

The ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor was successfully applied for the measurement of cholesterol in human serum, which implies that the biosensor has a potential application in clinical diagnostics.

Nanomaterial-based biosensors for measurement of lipids and lipoproteins towards point-of-care of cardiovascular disease

Cardiovascular disease (CVD) has become the primary cause of global deaths and inflicts an enormous healthcare burden on both developed and developing countries. Frequent monitoring of CVD-associated risk factors such as the level of lipids (e.g., triglyceride (TG) and total cholesterol (TC)) and lipoproteins (e.g., low-density lipoprotein (LDL) and high-density lipoprotein (HDL)) can effectively help prevent disease progression and improve clinical outcomes. However, measurement of these risk factors is generally integrated into an automated analyzer, which is prohibitively expensive and highly instrument-dependent for routine testing in primary care settings. As such, a variety of rapid, simple and portable nanomaterial-based biosensors have been developed for measuring the level of lipids (TG and TC) and lipoproteins (LDL and HDL) towards the management of CVD at the point-of-care (POC). In this review, we first summarize traditional methods for measurement of lipids and lipoproteins, and then present the latest advances in developing nanomaterial-based biosensors that can potentially monitor the risk factors of CVD at the POC.

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.

Localized surface plasmon resonance-based fiber-optic sensor for the detection of triacylglycerides using silver nanoparticles

A label-free technique for the detection of triacylglycerides by a localized surface plasmon resonance (LSPR)-based biosensor is demonstrated. An LSPR-based fiber-optic sensor probe is fabricated by immobilizing lipase enzyme on silver nanoparticles (Ag-NPs) coated on an unclad segment of a plastic clad optical fiber. The size and shape of nanoparticles were characterized by high-resolution transmission electron microscopy and UV-visible spectroscopy. The peak absorbance wavelength changes with concentration of triacylglycerides surrounding the sensor probe, and sensitivity is estimated from shift in the peak absorbance wavelength as a function of concentration. The fabricated sensor was characterized for the concentration of triacylglyceride solution in the range 0 to 7 mM. The sensor shows the best sensitivity at a temperature of 37°C and pH 7.4 of the triacylglycerides emulsion with a response time of 40 s. A sensitivity of 28.5  nm/mM of triacylglyceride solution is obtained with a limit of detection of 0.016 mM in the entire range of triacylglycerides. This compact biosensor shows good selectivity, stability, and reproducibility in the entire physiological range of triacylglycerides and is well-suited to real-time online monitoring and remote sensing.

Immobilization of Metal Hexacyanoferrate Ion-Exchangers for the Synthesis of Metal Ion Sorbents--A Mini-Review

Metal hexacyanoferrates are very efficient sorbents for the recovery of alkali and base metal ions (including radionuclides such as Cs). Generally produced by the direct reaction of metal salts with potassium hexacyanoferrate (the precursors), they are characterized by ion-exchange and structural properties that make then particularly selective for Cs(I), Rb(I) and Tl(I) recovery (based on their hydrated ionic radius consistent with the size of the ion-exchanger cage), though they can bind also base metals. The major drawback of these materials is associated to their nanometer or micrometer size that makes them difficult to recover in large-size continuous systems. For this reason many techniques have been designed for immobilizing these ion-exchangers in suitable matrices that can be organic (mainly polymers and biopolymers) or inorganic (mineral supports), carbon-based matrices. This immobilization may proceed by in situ synthesis or by entrapment/encapsulation. This mini-review reports some examples of hybrid materials synthesized for the immobilization of metal hexacyanoferrate, the different conditionings of these composite materials and, briefly, the parameters to take into account for their optimal design and facilitated use.

A nanostructured conductive hydrogels-based biosensor platform for human metabolite detection

The development of a scalable, low-cost, and versatile biosensor platform for the sensitive and rapid detection of human metabolites is of great interest for healthcare, pharmaceuticals, and medical science. On the basis of hierarchically nanostructured conducting polymer hydrogels, we designed a flexible biosensor platform that can detect various human metabolites, such as uric acid, cholesterol, and triglycerides. Owing to the unique features of conducting polymer hydrogels, such as high permeability to biosubstrates and rapid electron transfer, our biosensors demonstrate excellent sensing performance with a wide linear range (uric acid, 0.07-1 mM; cholesterol, 0.3-9 mM, and triglycerides, 0.2-5 mM), high sensitivity, low sensing limit, and rapid response time (∼3 s). Given the facile and scalable processability of hydrogels, the proposed conductive hydrogels-based biosensor platform shows great promise as a low-cost sensor kit for healthcare monitoring, clinical diagnostics, and biomedical devices.

A chitosan modified nickel oxide platform for biosensing applications

We present a highly sensitive and selective electrochemical sandwich immunosensor (the analyte is “sandwiched” between two antibodies) based on chitosan modified nickel oxide nanoparticles for the detection of Vibrio cholerae.

Lipase-modified pH-responsive microgel-based optical device for triglyceride sensing

Lipase-modified poly (N-isopropylacrylamide)-based microgels were synthesized, and used to fabricate optical devices (etalons). Triglyceride reacted with lipase to generate fatty acid, which yielded an etalon response.

Bioelectrocatalytic sensor for triglycerides in human skin sebum based on enzymatic cascade reaction of lipase, glycerol kinase and glycerophosphate oxidase

We report the development of an electrochemical biosensor for the quantification of triglycerides in human skin sebum, based on a multienzyme cascade reaction. The presence of excessive triglycerides in human sebum is one of the leading causes of various skin ailments. However, to the best of our knowledge, no bioelectrocatalytic approach for the quantification of sebum triglycerides has been made. In order to develop triglyceride biosensor, we fabricated a multienzyme-associated electrode incorporating lipase, glycerol kinase, and glycerophosphate oxidase. Enzymes were deposited by electrostatic force and further stabilized via crosslinking between enzymes and polymer matrices. The enzyme-modified biosensing electrode maintained its bioelectrocatalytic activity for five days. An additional constraint was the limited solubility of sebum triglycerides in aqueous electrolytes, impeding the analysis. To address this issue, triglyceride samples were prepared in the form of micelles, enabling efficient sample preparation for biosensor signaling. Calibration tests revealed that the designed assay had a detection range of 15-200mg/dL of micellar triglyceride, which covered the required determination range. The developed biosensing approach was successfully used to determine triglyceride concentrations in real sebum samples of unknown triglyceride content.