High Protein Binding Ability Research Articles

Investigating Membrane Material and Morphology for Development of Lateral Flow Biosensor

Development of membrane for bio–sensing applications, such as the detection of pathogens in drinking water for epidemics control has a huge global impact especially for public health. Membrane that applied in the bio–sensing devices should fulfill requirements such as high binding ability, fast lateral wicking time and low background staining. This paper explores the selection of membranes, including Nitrocellulose membrane (NC), Cellulose Acetate membrane (CA), Polyvinylidene Fluoride membrane (PVDF) and Nylon membrane for the detection of pathogens in water in the most efficient and rapid way. Membrane modification using glutaraldehyde enable the achieved of higher sensitivity of protein binding. Experimental findings (FTIR, porosity, membrane’s binding ability and lateral wicking time) verified the most suitable membrane for bio-sensing application. Among the tested membranes, NC appeared as the most suitable lateral flow membrane as its performances of high protein binding ability and fast lateral wicking time. Throughout this study, we showed the correlation of membrane’s material and morphology to its performances for pathogens detection in drinking water.

Selective binding and magnetic separation of histidine-tagged proteins using Fe3O4/Cu-apatite nanoparticles

Hierarchical Fe3O4@Cu-apatite nanoparticles (NPs) were synthesized via a facile hydrothermal method. The Fe3O4 cores present spherical shape and have a mean diameter of 300nm, and the Cu-apatite shell with thickness of about 50nm is composed of a large number of sheets. Using the high affinity of Cu2+ on the surface toward histidine tags, the Fe3O4@Cu-apatite NPs can be applied to enrich and magnetically separate histidine tagged (His-tagged) proteins directly from the mixture of lysed cells. Research results indicated that the Fe3O4@Cu-apatite NPs presented negligible nonspecific protein adsorption and high protein binding ability.

Nickel hydroxide/hydroxyapatite nanorods as affinity adsorbents for separation histidine-tagged proteins

Nickel hydroxide/hydroxyapatite (designated as Ni(OH)2/HAP) nanorods have been designed and synthesized by hydrothermal method. The size and morphology of Ni(OH)2/HAP sample depend strongly on the reaction condition, and introduction of small amount of Ni2+ ions would be propitious to get the smaller size nanorods. By taking advantage of the high affinity of Ni2+ ions toward histidine-tagged (His-tagged) proteins, the Ni(OH)2/HAP nanorods can be used to enrich and separate His-tagged proteins directly from a mixture of lysed cells, and their universality was evaluated by separating three kinds of His-tagged proteins. The Ni(OH)2/HAP nanorods present negligible nonspecific protein adsorption and high protein binding ability, and their specificity and affinity toward His-tagged proteins can be remained after 4 times recycling. The Ni(OH)2/HAP nanorods may provide many potential applications for the detection or separation of different biomolecules.

Synthesis of silica nanospheres with Ni2+-iminodiacetic acid for protein separation

Silica (SiO2) nanospheres (NSs) with immobilized metal ligands have been prepared for the affinity separation of proteins. First, SiO2 NSs were prepared by controlled hydrolysis of tetraethoxysilane in a basic aqueous-ethanol solution. Then through reaction of iminodiacetic acid (IDA) with 3-glycidoxypropyltrimethoxysilane and immobilization of them onto the surfaces of above SiO2 NSs, novel affinity adsorbents with IDA chelating groups were obtained. After chelating Ni2+ ions, the SiO2–IDA–Ni2+ NSs were applied to separate his-tagged proteins directly from the mixture of lysed cells. The SiO2–IDA–Ni2+ NSs present negligible nonspecific protein adsorption and high protein binding ability (28.3 mg/g).

Hierarchical Fe3O4@Ni x SiO y microspheres for affinity separation of His-tagged proteins

Hierarchical Fe3O4@Ni x SiO y microspheres (MSs) are synthesized via a facile hydrothermal method, using Fe3O4@SiO2 MSs as template. The prepared Fe3O4 cores present spherical shape and have a mean diameter of 500 nm, and the Ni x SiO y shell with thickness of 50 nm was composed of a large number of sheets. The Fe3O4@Ni x SiO y MSs are easily manipulated by an external magnetic force. By taking advantages of the high affinity of Ni2+ on the shell surface toward histidine-tagged (His-tagged) proteins, the Fe3O4@Ni x SiO y MSs can be applied to enrich and magnetically separate His-tagged proteins directly from the mixture of lysed cells. Research results indicated that the Fe3O4@Ni x SiO y MSs presented negligible nonspecific protein adsorption and high protein binding ability. These MSs with a high binding capacity of 14.6 mmol g−1 are much higher than that of commercial microbeads at only 10–12 mg g−1. Their specificity and affinity toward His-tagged proteins can be remained after four times recycling. The obtained Fe3O4@Ni x SiO y MSs are especially suitable for rapid purification of His-tagged proteins.

Iminodiacetic acid functionalized porous hydroxyapatite nanoparticles for capturing histidine-tagged proteins

A simple strategy has been developed to synthesize hydroxyapatite (HAP) nanoparticles (NPs) in a simulated body fluid (SBF). The HAP NPs have an average diameter of 50nm and present porous structure. By taking advantage of surface hydroxyl groups, the HAP NPs are further modified with iminodiacetic acid (IDA), followed by chelating Ni2+ ions. The HAP/IDA-Ni2+ NPs as novel adsorbent can capture directly histidine-tagged (His-tagged) proteins from the mixture of lysed cells without sample pretreatment. Results indicated that the HAP/IDA-Ni2+ NPs present negligible nonspecific adsorption and high protein binding ability, and their specificity and affinity toward His-tagged proteins can remain after 5 times of recycling. The HAP/IDA-Ni2+ NPs are especially suitable for purification of His-tagged proteins with low molecule weight.

Preparation of hollow nickel silicate nanospheres for separation of His-tagged proteins

Hollow nickel silicate nanospheres (NiSiO3 NSs) with hierarchical shells were hydrothermally synthesized by using silica spheres as a template. The NiSiO3 NSs have an average diameter of 250 nm with a shell thickness of 50 nm, and the hierarchical shell consists of a large number of sheets. By taking advantage of the high affinity of Ni(2+) toward histidine-tagged (His-tagged) proteins, hollow NiSiO3 NSs can be used to enrich and separate His-tagged proteins directly from a mixture of lysed cells. Results indicated that the hollow NiSiO3 NSs presented negligible nonspecific protein adsorption and a high protein binding ability with a high binding capacity of 13.2 mmol g(-1). Their specificity and affinity toward His-tagged proteins remained after recycling 5 times. The hollow NiSiO3 NSs are especially suitable for rapid purification of His-tagged proteins.

Optimization of Membrane Formulation and Process Variables via Crossed-Design Concept in Design of Experimental (DOE)

A mixture-process design methodology, i.e., the crossed design, is proposed for experimental analysis and optimization. Five mixture materials for membrane formulation and two process factors for casting condition were fixed in the design methodology. The study was to generate a regression model for each of the responses, based on the experimental data and analysis variance of the study. Based on the response models, the optimal blend and casting condition were predicted. The highest desirability function, D, which prevailed from the optimization was 0.66. This optimal blend composition of the cast solution and the process condition in crossed design is proven to increase the membrane performance through the high membrane porosity, the high protein binding ability, and the fast lateral wicking rate.

Optimization of membrane performance by thermal-mechanical stretching process using responses surface methodology (RSM)

Thermal-mechanical stretching process was proposed to modify membrane morphology for enhancing membrane performances. In this study, Response Surface Methodology (RSM) was used to achieve satisfactory responses of lateral flow membrane performances. The factors considered in this study were the stretching elongation (4–22% of the total membrane sample's length), stretching speed (0.04–0.1 mm/s) and stretching temperature (25–75 °C). The response variables included the lateral flow membrane performances in terms of porosity, lateral wicking time and protein binding ability. These responses were presented graphically based on the central composite design (CCD) of RSM. Atomic Force Microscope (AFM), Field Emission Scanning Electron Microscopy (FESEM) and statistical analysis showed that all the three stretching factors significantly affected the final membrane structures and performances. The optimum stretching elongation of membrane was found to be at 18% with the stretching rate and temperature of 0.07 mm/s and 35 °C respectively. This optimum stretching condition is proven to have high membrane porosity (78.63%), high protein binding ability (4496.5 μg/cm 3) and fast lateral wicking rate (579.0 s/4 cm) where deviation between predicted and actual responses fell within 5%.