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(Dongjie Yang, Shengyu Wang, Ruisheng Zhong, Weifeng Liu, Xueqing Qiu, pp. 630-642)
Lignin is one of the most abundant biomass resources and it makes up 20 wt-%‒30 wt-% of lignocellulose. It endows plants with their natural toughness and UV resistance. The pulp and paper pulping industry generates more than 50 million tons of technical lignin annually. However, most of the technical lignin is not properly utilized. Lignin is renewable, biodegradable, non-toxic, inexpens
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This chapter is an introduction to nanocomposite materials and its classifications with emphasis on orthopedic application. It covers different types of matrix nanocomposites including ceramics, metal, polymer and natural-based nanocomposites with the main features and applications in the orthopedic. In addition, it presents structure, composition, and biomechanical features of bone as a natural nanocomposite. Finally, it deliberately presents developing methods for nanocomposites bone grafting.
Poly(D,L-lactic-co-glycolic acid) (PLGA)/poly(lactic acid) (PLA) microspheres/nanoparticles are one of the most successful drug delivery systems (DDS) in lab and clinic. Because of good biocompatibility and biodegradability, they can be used in various areas, such as long-term release system, vaccine adjuvant, tissue engineering, etc. There have been 15 products available on the US market, but the system still has many problems during development and manufacturing, such as wide size distribution, drug stability issues, and so on. Recently, many new and modified methods have been developed to overcome the above problems. Some of the methods are easy to scale up, and have been available on the market to achieve pilot scale or even industrial production scale. Furthermore, the relevant FDA guidance on the DDS is still incomplete, especially for abbreviated new drug application. In this review, we present some recent achievement of the PLGA/PLA microspheres/nanoparticles, and discuss some promising manufacturing methods. Finally, we focus on the current FDA guidance on the DDS. The review provides an overview on the development of the system in pharmaceutical industry.
In recent years, nanostructured oxide films on titanium alloy surfaces have gained significant interest due to their electrical, catalytic and biological properties. In literature, there is variety of different approaches to fabricate nanostructured oxide films. Among these methods, anodization technique, which allows fine-tuning of oxide film thickness, feature size, topography and chemistry, is one of the most popular approaches to fabricate nanostructured oxide films on titanium alloys, and it has been widely investigated for orthopedic applications. Briefly, anodization is the growth of a controlled oxide film on a metallic component attached to the anode of an electrochemical cell. This review provides an overview of the anodization technique to grow nanostructured oxide films on titanium and titanium alloys and summarizes the interactions between anodized titanium alloy surfaces with cells in terms of cellular adhesion, proliferation and differentiation. It will start with summarizing the mechanism of nanofeatured oxide fabrication on titanium alloys and then switch its focus on the latest findings for anodization of titanium alloys, including the use of fluoride free electrolytes and anodization of 3D titanium foams. The review will also highlight areas requiring further research to successfully translate anodized titanium alloys to clinics for orthopedic applications.
Due to a worldwide focus on sustainable materials for human health and economy services, more and more natural renewable biomass are regarded as promising materials that could replace synthetic polymers and reduce global dependence on petroleum resources. Cellulose is known as the most abundant renewable polymer in nature, varieties of cellulose-based products have been developed and have gained growing interest in recent years. In this review, a kind of water-soluble cellulose derivative, i.e., sodium cellulose sulfate (NaCS) is introduced. Details about NaCS’s physicochemical properties like solubility, biocompatibility, biodegradability, degree of substitution, etc. are systematically elaborated. And promising applications of NaCS used as biomaterials for microcarriers’ designing, such as micro-cell-carriers, micro-drug-carriers, etc., are presented.
A simple method using a water soluble lignin quaternary ammonium salt (LQAS) and TiO2 has been developed for the preparation of lignin/TiO2 nanocomposites in an aqueous medium under mild conditions. The LQAS/TiO2 nanocomposites contain well-dispersed small particles with excellent ultraviolet (UV) shielding abilities and good compatibilities with waterborne polyurethane (WPU). When the LQAS/TiO2 nanocomposites were blended with WPU, the UV absorbance and the tensile ductility of the WPU increased significantly. The composite WPU hybrid film containing 6 wt-% LQAS/TiO2 nanocomposite had the highest visible light transmittance and had excellent ultraviolet aging properties. After 192 h of UV light irradiation, the tensile strength of the composite film was above 8 MPa and the elongation at break was 800%. This work highlights new possibilities for the utilization of alkali lignin.
The mixed-mode resins for protein adsorption have been prepared by a novel strategy, copolymer grafting. Specially, the copolymer-grafted resins CG-M-A with two functional groups, 5-amino-benzimidazole (ABI) and methacryloxyethyltrimethyl ammonium chloride (METAC), have been prepared through surface-initiated activator generated by electron transfer for atom transfer radical polymerization of METAC and glycidyl methacrylate (GMA), followed by a ring-open reaction to introduce ABI. The charge and hydrophobicity of CG-M-A resins could be controlled by manipulating the addition of METAC and GMA/ABI. Besides, METAC and ABI provided positive effects together in both protein adsorption and elution: dynamic binding capacity of human Immunoglobulin G (hIgG) onto CG-M-A resin with the highest ligand ratio of METAC to ABI is 46.8 mg·g−1 at pH 9 and the elution recovery of hIgG is 97.0% at pH 5. The separation experiment showed that purity and recovery of monoclonal antibody from cell culture supernatant are 96.0% and 86.5%, respectively, indicating that copolymer-grafted mixed-mode resins could be used for antibody purification.
1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne polyurethane (WPU) dispersions have been successfully prepared by a prepolymer process from 1,5-pentamethylene diisocyanate poly(polyether) with different NCO/OH ratios and 1,6-hexanediol (HDO)/dimethylol propionic acid (DMPA) molar ratios. The Fourier transform infrared (FTIR) spectra, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and a mechanical tensile test were used to investigate the structures, thermal stability, phase separation, crystallinity, mechanical properties, and adhesive performance of the WPU dispersions. The FTIR results indicate that the degree of hydrogen bonding and the numbers of urea groups increase as the NCO/OH ratio and HDO/DMPA molar ratio increase. Furthermore, the phase separation increases and the thermal stability decreases as the NCO/OH ratio increases or the HDO/DMPA molar ratio decreases. Finally, WPU3.0-2.4 (NCO/OH=3, HDO/DMPA=2.4) exhibits a maximum tensile strength and shear strength, pointing to its possible use as an adhesive. These results could provide a very valuable reference for industrial applications of WPU.
The potential applications of nanomaterials used in nanomedicine as ingredients in drug delivery systems and in other products continue to expand. When nanomaterials are introduced into physiological environments and driven by energetics, they readily associate proteins forming a protein corona (PC) on their surface. This PC could result in an alteration of the nanomaterial’s surface characteristics, affecting their interaction with cells due to conformational changes in adsorbed protein molecules. However, our current understanding of nanobiological interactions is still very limited. Utilizing a liquid chromatography–mass spectroscopy/mass spectroscopy technology and a Cytoscape plugin (ClueGO) approach, we examined the composition of the PC for a set of zinc oxide nanoparticles (ZnONP) from cell culture media typically and further analyzed the biological interaction of identified proteins, respectively. In total, 36 and 33 common proteins were investigated as being bound to ZnONP at 5 min and 60 min, respectively. These proteins were further analyzed with ClueGO, a Cytoscape plugin, which provided gene ontology and the biological interaction processes of identified proteins. Proteins bound to the surface of nanoparticles that may modify the structure, therefore the function of the adsorbed protein could be consequently affect the complicated biological processes.
Cholesterol plays a significant role in the organization of lipids and modulation of membrane dynamics in mammalian cells. However, the effect of cholesterol depletion on the eukaryotic cell membranes seems controversial. In this study, the effects of cholesterol on the topography and mechanical behaviors of CHO-K1 cells with manipulated membrane cholesterol contents were investigated by atomic force microscopy (AFM) technique. Here, we found that the depletion of cholesterol in cell membranes could increase the membrane stiffness, reduce the cell height as well as promote cell retraction and detachment from the surface, whereas the cholesterol restoration could reverse the effect of cholesterol depletion on the membrane stiffness. Increased methyl-β-cyclodextrin levels and incubation time could significantly increase Young’s modulus and degree of stiffing on cell membrane and cytoskeleton. This research demonstratede importance of cholesterol in regulating the dynamics of cytoskeleton-mediated processes. AFM technique offers excellent advantages in the dynamic monitoring of the change in membranes mechanical properties and behaviors during the imaging process. This promising technology can be utilized in studying the membrane properties and elucidating the underlying mechanism of distinct cells in the near-native environment.
Plants have been used for medicinal purposes for thousands of years but they are still finding new uses in modern times. For example, Elaeagnus angustifolia (EA) is a medicinal herb with antinociceptive, anti-inflammatory, antibacterial and antioxidant properties and it is widely used in the treatment of rheumatoid arthritis and osteoarthritis. EA extract was loaded onto poly(ϵ-caprolactone)-poly(ethylene glycol)-poly(ϵ-caprolactone) (PCL-PEG-PCL/EA) nanofibers and their potential applications for bone tissue engineering were studied. The morphology and chemical properties of the fibers were evaluated using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, contact angle measurements and mechanical tests. All the samples had bead-free morphologies with average diameters ranging from 100 to 200 nm. The response of human cells to the PCL-PEG-PCL/EA nanofibers was evaluated using human dental pulp stem cells (hDPSCs). The hDPSCs had better adhesion and proliferation capacity on the EA loaded nanofibers than on the pristine PCL-PEG-PCL nanofibers. An alizarin red S assay and the alkaline phosphatase activity confirmed that the nanofibrous scaffolds induced osteoblastic performance in the hDPSCs. The quantitative real time polymerase chain reaction results confirmed that the EA loaded nanofibrous scaffolds had significantly upregulated gene expression correlating to osteogenic differentiation. These results suggest that PCL-PEG-PCL/EA nanofibers might have potential applications for bone tissue engineering.
In this work, we have synthesized two polymer-grafted cation exchangers: one via the grafting-from approach, in which sulfopropyl methacrylate (SPM) is grafted through atom transfer radical polymerization onto Sepharose FF (the thus resulting exchanger is referred as Sep-g-SPM), and another via the grafting-to approach, in which the polymer of SPM is directly coupled onto Sepharose FF (the thus resulting exchanger is called as Sep-pSPM). Protein adsorption on these two cation exchangers have been also investigated. At the same ligand density, Sep-g-SPM has a larger accessible pore radius and a smaller depth of polymer layer than Sep-pSPM, due to the controllable introduction of polymer chains with the regular distribution of the ligand. Therefore, high-capacity adsorption of lysozyme and γ-globulin could be achieved simultaneously in Sep-g-SPM with an ionic capacity (IC) of 308 mmol·L−1. However, Sep-pSPM has an irregular chain distribution and different architecture of polymer layer, which lead to more serious repulsive interaction to proteins, and thus Sep-pSPM has a lower adsorption capacity for γ-globulin than Sep-g-SPM with the similar IC. Moreover, the results from protein uptake experiments indicate that the facilitated transport of adsorbed γ-globulin occurs only in Sep-pSPM and depends on the architecture of polymer layers. Our research provides a clear clue for the development of high-performance protein chromatography.
In Lactococcus lactis, the global transcriptional regulatory factor CodY can interact with the promoter DNA to regulate the growth, metabolism, environmental adaptation and other biological activities of the strains. In order to study the mechanism of interaction between CodY and its target DNA, molecular docking and molecular dynamics simulations were used to explore the binding process at molecular level. Through the calculations of the free energy of binding, hydrogen bonding and energy decomposition, nine key residues of CodY were identified, corresponding to SER184, SER186, SER208, THR217, ARG218, SER219, ASN223, LYS242 and GLY243, among which SER186, ARG218 and LYS242 play a vital role in DNA binding. Our research results provide important theoretical guidance for using wet-lab methods to study and optimize the metabolic network regulated by CodY.
Environmental and energy concerns have increased interest in renewable energy sources, particularly biofuels. Thus the fermentation of glucose from sulfuric acid-hydrolyzed corn stover for the production of bioethanol has been explored using a combined acid retardation and continuous-effect membrane distillation treatment process. This process resulted in the separation of the sugars and acids from the acid-catalyzed hydrolysate, the removal of most of the fermentation inhibitors from the hydrolysate and the concentration of the detoxified hydrolysate. The recovery rate of glucose from the sugar-acid mixture using acid retardation was greater than 99.12% and the sulfuric acid was completely recovered from the hydrolysate. When the treated corn stover hydrolysate, containing 100 g/L glucose, was used as a carbon source, 43.06 g/L of ethanol was produced with a productivity of 1.79 g/(L∙h) and a yield of 86.31%. In the control experiment, where glucose was used as the carbon source these values were 1.97 g/(L∙h) and 93.10% respectively. Thus the integration of acid retardation and a continuous-effect membrane distillation process are effective for the production of fuel ethanol from corn stover.
A response surface method was used to optimize the purification and concentration of gluconic acid from fermentation broth using an integrated membrane system. Gluconobacter oxydans was used for the bioconversion of the glucose in sugarcane juice to gluconic acid (concentration 45 g∙L−1) with a yield of 0.9 g∙g−1. The optimum operating conditions, such as trans-membrane pressure (TMP), pH, cross-flow rate (CFR) and initial gluconic acid concentration, were determined using response surface methodology. Five different types of polyamide nanofiltration membranes were screened and the best performing one was then used for downstream purification of gluconic acid in a flat sheet cross-flow membrane module. Under the optimum conditions (TMP= 12 bar and CFR= 400 L∙h−1), this membrane retained more than 85% of the unconverted glucose from the fermentation broth and had a gluconic acid permeation rate of 88% with a flux of 161 L∙m−2∙h−1. Using response surface methods to optimize this green nanofiltration process is an effective way of controlling the production of gluconic acid so that an efficient separation with high flux is obtained.
Chalcogenide nanostructured semiconductor, copper sulfide (CuS) was prepared from copper and sulfur powders in stoichiometric ratio by a simple, fast, and convenient one-step mechanochemical synthesis after 40 min of milling in an industrial eccentric vibratory mill. The kinetics of the mechanochemical synthesis and the influence of the physical properties of two Cu powder precursor types on the kinetics were studied. The crystal structure, physical properties, and morphology of the product were characterized by X-ray diffraction (XRD), the specific surface area measurements, particle size distribution and scanning electron microscopy. The XRD analysis confirmed the hexagonal crystal structure of the product-CuS (covellite) with the average size of the crystallites 11 nm. The scanning electron microscopy analysis has revealed that the agglomerated grains have a plate-like structure composed of CuS nanoparticles. The thermal analysis was performed to investigate the thermal stability of the mechanochemically synthesized CuS. The optical properties were studied using UV-Vis and photoluminescence spectroscopy. The determined optical band gap energy 1.80 eV responds to the value of the bulk CuS, because of agglomerated nanoparticles. In addition, a mechanism of CuS mechanochemical reaction was proposed, and the verification of CuS commercial production was performed.
The europium heptadentate coordinatively unsaturated (Eu(III)) and the terbium (Tb(III)) 1,4,7,10-tetraazacyclododecane (cyclen) complexes 1 and 2 were used in conjunction with ligand 3 (1,3,5-benzene-trisethynylbenzoate) to form the supramolecular self-assembly structures 4 and 5; this being investigated in both the solid and the solution state. The resulting self-assemblies gave rise to metal centered emission (both in the solid and solution) upon excitation of 3, confirming its role as a sensitizing antenna. Drop-cased examples of ligand 3, and the solid forms of 4 and 5, formed from both organic and mixture of organic-aqueous solutions, were analyzed using Scanning Electron Microscopy, which showed significant changes in morphology; the ligand giving rise to one dimensional structures, while both 4 and 5 formed amorphous materials that were highly dense solid networks containing nanoporous features. The surface area (216 and 119 m2·g−1 for 4 and 5 respectively) and the ability of these porous materials to capture and store gases such as N2 investigated at 77 K. The self-assembly formation was also investigated in diluted solution by monitoring the various photophysical properties of 3–5. This demonstrated that the most stable structures were that consisting of a single antennae 3 and three complexes of 1 or 2 (e.g., 4 and 5) in solution. By monitoring the excited state lifetimes of the Eu(III) and Tb(III) ions in H2O and D2O respectively, we showed that their hydration states (the q-value) changed from ~2 to 0, upon formation of the assemblies, indicating that the three benzoates of 3 coordinated directly to the each of the three lanthanide centers. Finally we demonstrate that this hierarchically porous materials can be used for the sensing of organic solvents as the emission is highly depended on the solvent environment; the lanthanide emission being quenched in the presence of acetonitrile and THF, but greatly enhanced in the presence of methanol.
An appropriate co-catalyst can significantly promote the photocatalytic efficacy, but this has been seldom studied in the visible-light photocatalysis combined with ozone, namely photocatalytic ozonation. In this work, a dendritic bismuth vanadium tetraoxide (BiVO4) material composited with highly dispersed MnOx nanoparticles was synthesized, and its catalytic activity is 86.6% higher than bare BiVO4 in a visible light and ozone combined process. Catalytic ozonation experiments, ultra-violet-visible (UV-Vis) diffuse reflectance spectra and photoluminescence spectra jointly indicate that MnOx plays a triple role in this process. MnOx strengthens the light adsorption and promotes the charge separation on the composite material, and it also shows good activity in catalytic ozonation. The key reactive species in this process is ·OH, and various pathways for its generation in this process is proposed. This work provides a new direction of catalyst preparation and pushes forward the application of photocatalytic ozonation in water treatment.
Though they reduce microorganism growth, current hospital disinfectants also damage many of today’s modern electronic devices such as tablets and smartphones. Herein, the efficacy of a new chlorhexidine digluconate gel (CDG) was tested as a disinfectant for mobile and electronic devices in a clinical environment. Specifically, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus were used to infect the screen of eight smartphones. The CDG was prepared at concentrations of 2%, 4% and 6%, and tested on paper disks infected with these bacteria before being tested on the smartphones. The devices were disinfected with the CDG gel (4%) at two times: immediately and after 5 min of the bacterial contamination. In all cases, the CDG gel eliminated 100% of gram-positive and gram-negative microorganisms compared to the control (without any agent). In addition, the gel did not damage the smartphones. Therefore, our study suggests that the CDG gel may be applied to disinfect a wide range of electronic devices for health care professionals in the hospital environment.
