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.

Protein recovery as a resource from waste specifically via membrane technology-from waste to wonder

Economic growth and the rapid increase in the world population has led to a greater need for natural resources, which in turn, has put pressure on said resources along with the environment. Water, food, and energy, among other resources, pose a huge challenge. Numerous essential resources, including organic substances and valuable nutrients, can be found in wastewater, and these could be recovered with efficient technologies. Protein recovery from waste streams can provide an alternative resource that could be utilized as animal feed. Membrane separation, adsorption, and microbe-assisted protein recovery have been proposed as technologies that could be used for the aforementioned protein recovery. This present study focuses on the applicability of different technologies for protein recovery from different wastewaters. Membrane technology has been proven to be efficient for the effective concentration of proteins from waste sources. The main emphasis of the present short communication is to explore the possible strategies that could be utilized to recover or restore proteins from different wastewater sources. The presented study emphasizes the applicability of the recovery of proteins from various waste sources using membranes and the combination of the membrane process. Future research should focus on novel technologies that can help in the efficient extraction of these high-value compounds from wastes. Lastly, this short communication will evaluate the possibility of integrating membrane technology. This study will discuss the important proteins present in different industrial waste streams, such as those of potatoes, poultry, dairy, seafood and alfalfa, and the possible state of the art technologies for the recovery of these valuable proteins from the wastewater.

Defect engineering, microstructural examination and improvement of ultrafast third harmonic generation in GaZnO nanostructures: a study of e-beam irradiation

Electron beam induced effects on defect engineering and structural, morphological and optical properties of Ga doped ZnO (GaZnO) nanostructures for improved ultrafast nonlinear optical properties are presented. A microstructural analysis was carried out based on the Scherrer, Williamson-Hall, and size-strain models. All three models reveal a peak broadening effect upon electron beam irradiation (EBI) and the crystallite size of the films shows a decrease of 30% compared to unirradiated nanostructures. The decrease in intensity, variation in the peak position and broadening of the Raman E2H mode confirm that the EBI treatment introduces disorder into the nanostructures. The interband gap emissions observed in photoluminescence spectra are primarily due to defect-related emissions originating from intrinsic defects such as Zni, Oi, VZn, VO, VZn+, VO+ and OZn. The O1s core-level spectra show that the peak related to oxygen vacancy defects is suppressed upon EBI. Surface morphology studies reveal that the nucleation barriers of GaZnO nanostructures are reduced upon irradiation treatment resulting in a coalescence mechanism. Third harmonic generation studies show that higher electron-beam doses lead to the occurrence of enhanced THG signals due to a drastic change in the occupation of localized defect levels. Thermally induced nonlinear optical studies depict an improved χ(3) of 1.71 × 10-3 esu upon irradiation due to enhanced FCA induced TPA mechanism and non-radiative transitions which indicates the credibility of the grown films in photonic devices.

Hexadecyltrimethylammonium Bromide Surfactant-Supported Silica Material for the Effective Adsorption of Metanil Yellow Dye

The adsorption behavior of an organic dye, metanil yellow (My), from water using micro-nano silica particles (MNSPs) was investigated. MCM-41-like (Mobil Composition of Matter No. 41) MNSPs were synthesized using tetraethoxy orthosilicate as a silica source and hexadecyltrimethylammonium bromide (CTAB) as a surfactant under basic conditions. Comparative studies were performed to assess the adsorption behaviors of the organic dye using the as-synthesized MCM-41 before the removal of CTAB and MCM-41, either after one, two, and three times of chemical etching or after calcination. My was adsorbed more effectively from water on the as-synthesized MCM-41 without the removal of the surfactant than on MCM-41 after the removal of the surfactant by chemical etching or calcination. In addition, MCM-41 after removing the surfactant by one-time chemical etching in the presence of hydrochloric acid also showed better adsorption of My from water than MCM-41 after removing the surfactant by further two and three times of chemical etching or calcination. For comparison, other kinds of dye molecules with different chemical structures such as methylene blue (Mb) and rhodamine B (Rb) were also used to check the possibility of adsorption of various dyes by the CTAB-supported MNSPs. To better understand the reason behind the adsorption phenomena, detailed studies on the kinetics and thermodynamics of adsorption of the MNSPs were performed. Excellent adsorption of My was observed at concentrations up to 100 mg L^-1 at 25 °C, whereas the adsorption was lower at higher concentrations of the My dye. Furthermore, enhanced My dye adsorption was observed at higher concentrations by increasing the adsorption temperature. It can be concluded that the MNSPs exhibited efficient adsorption of My, when the MNSPs are used without the removal of the surfactant and any further modifications, suggesting that the surfactant played key roles in the effective adsorption of the anionic dye. The as-synthesized MCM-41 was, however, not a good adsorbent for cationic dyes such as Mb and Rb.

A novel strategy to synthesize dual-responsive polymeric nanocarriers for investigating the activity and stability of immobilized pectinase

A dual-stimuli-responsive support material for pectinase immobilization through ionic bonding was prepared. Specifically, polystyrene-b-polymethylacrylic (PS-b-PMAA), light- and pH-sensitive polystyrene-(5-propargylether-2-nitrobenzyl bromoisobutyrate)-b-poly(diethylamino)ethyl methacrylate-b-poly(polyethylene glycol methacrylate) (PS-ONB-PDEAEMA-b-PPEGMA) were synthesized through atom transfer radical polymerization, click chemistry, and hydrolysis. The two parts could self-assemble into the micelles in an aqueous solution. The micelles shrunk at a higher pH, and their size reduced under UV irradiation. The stimuli-responsive properties of micelles were characterized by dynamic light scattering and transmission electron microscopy. It has been found that this support was able to adsorb 10 U/mL of immobilized pectinase (approximately 223 mg/g) at pH 5.0 and 60 °C for 60 Min. Meanwhile, the highest relative activity of immobilized pectinase was up to approximately 95% at pH 5.0 and 60 °C. The immobilized pectinase retained more than 50% of the initial activity after eight cycles. The relative activity of the pectinase immobilized on the supports without UV irradiation was approximately 3% lower than that after UV irradiation at 60 °C, indicating that tailoring of enzyme activity was achieved by changing environmental conditions. Apparently, the original enzymatic support material had a great application prospect on enzyme immobilization.

Laccase-immobilized tannic acid-mediated surface modification of halloysite nanotubes for efficient bisphenol-A degradation

Halloysite nanotubes (HNTs) have been pursued as promising carriers for enzyme immobilization, but the lack of functional groups severely limits their applications. Herein, we reported a simple tannic acid (TA)-mediated surface modification strategy for the fabrication of HNT-based efficient enzyme immobilization supports. Particularly, TA was first self-polymerized and deposited onto the surface of HNTs to form a thin active film via a mussel-inspired method, and the model enzyme laccase was directly conjugated via the Michael addition and/or Schiff base condensation between quinone groups on poly(tannic acid) layer surfaces and exposed amine groups on laccase surfaces. Under the optimum conditions, this newly fabricated support retained good enzyme-loading and activity recovery properties with 197.9 mg protein per gram of support and 55.4% of activity recovery being achieved. In addition, this immobilized laccase was less influenced by pH, temperature, and inhibitor changes and exhibited higher storage stability than free laccases as more than 70% of initial activity was retained by the immobilized laccase, while less than 30% was retained for free laccase after one-month storage at 4 °C. Finally, a higher bisphenol-A (BPA) removal efficiency and more reuse cycles were demonstrated for immobilized laccases. As a result, this TA-mediated surface modification is a simple and green method for biological macromolecule immobilization on HNTs in one step.

We report a simple tannic acid (TA)-mediated surface modification strategy for the fabrication of HNT-based efficient enzyme immobilization supports.

Biocompatible magnetic nanoparticles grafted by poly(carboxybetaine acrylamide) for enzyme immobilization

Herein, the zwitterionic material poly (carboxybetaine acrylamide) was grafted onto iron oxide to obtain biocompatible magnetic nanoparticles Fe₃O₄-pCBAA which were employed to immobilize enzymes. The nanocomplxes Fe₃O₄-pCBAA were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential, Fourier transform-infrared (FT-IR) spectra and energy dispersive X-ray spectrometry (EDX). The urease as a model enzyme was immobilized with the novel supports and the properties of immobilized urease were further investigated in comparison with the free urease counterpart. The immobilized urease exhibited excellent thermodynamic and chemical stability. Particularly, 60% of initial activity was remained after being stored at 70 °C for 2 h while the free urease only remained 30%. Besides, the relative activity of immobilized enzyme was 1.7 times that of free ones after disposed in ethanol and 2-propanol for 2 h, and 7 times in DMF. Moreover, immobilized urease retained >80% of its initial activity after 5 cycles. In addition, the immobilization carrier Fe₃O₄-pCBAA displayed famous biocompatibility, and the immobilized urease performed better in complex biological samples, which were >85% and <60% of its initial activity for the immobilized and dissociative urease, respectively, in 20% and 25% of serum. These results confirm that the nanoparticles Fe₃O₄-pCBAA are biofriendly and efficient supports for enzyme immobilization and potential for practical applications in bio-microenvironments.

A novel approach for tailoring structural, morphological, photoluminescence and nonlinear optical features in spray coated Cu:ZnO nanostructures via e-beam

We present electron beam induced modifications on structural, morphological, and optical properties of spray coated Cu doped ZnO thin films for nonlinear optical applications.

Study of Molecular Conformation and Activity-Related Properties of Lipase Immobilized onto Core-Shell Structured Polyacrylic Acid-Coated Magnetic Silica Nanocomposite Particles

A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100,000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently immobilized onto the particles with an average diameter of 210 ± 50 nm, resulting from high binding sites concentrations on the low- and high-molecular-weight PAA-coated particles, high lipase immobilization efficiencies (86.2% and 89.9%, respectively), and loading capacities (786 and 816 mg g(-1), respectively) are obtained. Results from circular dichroism (CD) analysis and catalytic activity tests reveal an increase in the β-sheet content of lipase molecules upon immobilization, along with an enhancement in their activities and stabilities. The lipases immobilized onto the low- and high-molecular-weight PAA-coated particles show maximum activities at 55 and 50 °C, respectively, which are ∼28% and ∼15% higher than that of the free lipase at its own optimum temperature (40 °C), respectively. The immobilized lipases exhibit excellent performance at broader temperature and pH ranges and high thermal and storage stabilities, as well as superior reusability. These prepared magnetic nanocomposite particles can be offered as suitable support materials for efficient immobilization of enzymes and improvement of the immobilized enzymes properties.

Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40

A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H₂O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H₂O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification.

Immobilization of acetylcholinesterase on electrospun poly(acrylic acid)/multi-walled carbon nanotube nanofibrous membranes

The immobilized enzyme on nanofibrous samples maintained more than 90% of its original activity even after 10 cycles of reusing.

Amine-functionalized magnetic nanocomposite particles for efficient immobilization of lipase: effects of functional molecule size on properties of the immobilized lipase

The size of functional molecules influences the immobilization efficiency and properties of lipase immobilized on amine-functionalized magnetite–silica nanocomposite particles.

Enantioselective transesterification of (R,S)-2-pentanol catalyzed by a new flower-like nanobioreactor

The lipase-incorporated nanoflower was prepared and used for the resolution of (R,S)-2-pentanol with vinyl acetate as acyl donor in n-hexane.

Synthesis of mono-dispersed mesoporous SBA-1 nanoparticles with tunable pore size and their application in lysozyme immobilization

We reported the facile synthesis of mono-dispersed SBA-1 nanoparticles with ordered pore structure and tunable pore size. It is demonstrated that both the pore structure and pore size played important roles in lysozyme immobilization.