Enzyme sensor for simultaneous determination of cholesterol, triglyceride and HDL cholesterol in serum

A three-electrode lipid biosensor that simultaneously measures the total cholesterol (CHO), triglyceride (TG), and HDL cholesterol (HDL-C) in standard serum has been developed. The lipid biosensor is designed for clinical use where production cost, low sample requirement, portability, stability, and speed are high priorities. The device design filters out blood cells and lipoproteins from the serum, where the target molecules are catalyzed by enzymes encapsulated in carboxymethyl cellulose (CMC) to produce electron mediators, potassium ferrocyanide. These electron mediators were subsequently detected by amperometric determination. The sensor exhibit high selectivity towards the targets and can measure the target lipids in 4 min with 10 µL of serum. Lastly, the device can be stored up to 18 months with a minimal decrease in catalytic efficiency.

Based on Gold Nanoparticles-L-Tyr-Amino Functionalized Mesoporous Materials-Polyphenol Oxidase Modified Biosensor for the Detection of Resorcinol

Nowadays, resorcinol (RC) has been widely applied in the chemical and pharmaceutical industries. However, the electrochemical detection technique of RC still features some significant drawbacks, for instance, a low sensitivity. Hence, in the present work, a glass carbon electrode was developed for the electrochemical detection of RC with good specificity and stability, through modifying the glass carbon electrode (GCE) by polyphenol oxidase (PPO), an NH₂-SBA-15 mesoporous material (NH₂-SBA-15), L-tyrosine (L-Tyr) and gold nano-particles (AuNPs). After being successively modified by AuNPs, L-Tyr, NH₂-SBA-15 and PPO, the constructed PPO/NH₂-SBA-15/L-Tyr/AuNPs/GCE was used to discriminate RC from ions and other common micromolecules, which showed a fairly good specificity and stability. The proposed electrochemical detection method features a linear range of from 0.5 to 21.0 μM with a LOD down to 0.15 μM, revealing a better sensitivity than the existing methods. It is worth mentioning that the proposed PPO/NH₂-SBA-15/L-Tyr/AuNPs/GCE has been successfully used as an electrochemical probe for the RC assay in domestic sewage.

Structural Characterization of Proteins Adsorbed at Nanoporous Materials

A nanoporous material has been applied for the development of functional nanobiomaterials by utilizing its uniform pore structure and large adsorption capacity. The structure and stability of biomacromolecules, such as peptide, oligonucleotide, and protein, are primary factors to govern the performance of nanobiomaterials, so that their direct characterization methodologies are in progress. In this review, we focus on recent topics in the structural characterization of protein molecules adsorbed at a nanoporous material with uniform meso-sized pores. The thermal stabilities of the adsorbed proteins are also summarized to discuss whether the structure of the adsorbed protein molecules can be stabilized or not.

In-situ Neutron Reflectometry Study on Adsorption of Glucose Oxidase at Mesoporous Aluminum Oxide Film

In the present study, the adsorption of glucose oxidase (GOD) to a mesoporous aluminum oxide (MAO) film was examined with in-situ neutron reflectometry (NR) measurements. The MAO film was deposited on a cover glass slip and a Si disc, and its pore structure was characterized by X-ray reflectometry (XRR) and NR. The Si disc with MAO film was applied for an in-situ NR experiment, and its NR profiles before/after adsorption of GOD were continuously measured with a flow cell. The results indicated that the negatively-charged GOD molecules hardly penetrate into the narrow pore channel (pore diameter = ca. 10 nm) with opposite surface charge.

Differential Scanning Calorimetry Study on the Adsorption of Myoglobin at Mesoporous Silicas: Effects of Solution pH and Pore Size

In the present study, pore adsorption behavior of globular myoglobin (Mb) at mesoporous silicas was examined utilizing the low-temperature differential scanning calorimetry (DSC) method. The DSC method relies on a decrease in heat of fusion for the pore water upon adsorption of Mb. The amount and structure of Mb adsorbed into the mesoporous silica were examined by DSC and optical absorption spectroscopy. The results indicated that the pore adsorption behavior of Mb strongly depended on the solution pH and pore size of mesoporous silica. For the adsorption of Mb (diameter = 3.5 nm) into mesoporous silica with narrow pores (pore diameter = 3.3 nm) at a pH ranging from 7.0 to 3.7, the penetration of both folded and denatured Mb molecules was confirmed. The folded Mb could penetrate into large mesoporous silica pores (pore diameter = 5.3 and 7.9 nm), whereas the penetration of the denatured Mb molecules was completely inhibited. The distribution of folded Mb at mesoporous silica depended on the pore size; almost all folded Mb molecules located inside mesoporous silica pores of diameters 3.3 and 5.3 nm, whereas the Mb molecules distributed at bot internal and external pore surfaces of mesoporous silica with 7.9 nm in pore diameter. These pore adsorption behaviors suggest that aggregation or stacking of the Mb molecules at the pore entrance regions of the large pores affected the pore adsorption behavior.

Characterization of Myoglobin Adsorption into Mesoporous Silica Pores by Differential Scanning Calorimetry

Adsorption of protein molecules into the pores of a porous material is an important process for chromatographic separation of proteins and synthesis of nanoscale biocatalyst systems; however, there are barriers to developing a method for analyzing the process quantitatively. The purpose of this study is to examine the applicability of differential scanning calorimetry (DSC) for quantitative analysis of protein adsorption into silica mesopores. For this purpose myoglobin, a globular protein (diameter: 35.2 Å) was selected, and its adsorption onto mesoporous silica powders with uniform pore diameters (pore diameters: 39 and 64 Å) was measured by adsorption assay and DSC experiments. Our results confirmed that the adsorption of myoglobin into the silica mesopores induced significant changes in the positions and areas of freezing/melting peaks of the pore water. The decrease in heat of fusion of the pore water after myoglobin adsorption could be utilized to quantify the amount of myoglobin inside the silica mesopores. The advantages of DSC include its applicability to small wet mesoporous silica samples.

A novel N/Au co-doped carbon dot probe for continuous detection of silicate and phosphate by resonance Rayleigh scattering

Co-doped carbon dots are new multifunctional carbon nanomaterials.