Filter made of cuprammonium regenerated cellulose for virus removal: a mini-review

In 1989, Asahi Kasei commercialized a porous hollow fiber membrane filter (Planova™) made of cuprammonium regenerated cellulose, making it possible for the first time in the world to “remove viruses from protein solutions by membrane filtration”. Planova has demonstrated its usefulness in separating proteins and viruses. Filters that remove viruses from protein solutions, i.e., virus removal filters (VFs), have become one of the critical modern technologies to assure viral safety of biological products. It has also become an indispensable technology for the future. The performance characteristics of VFs can be summarized in two points: 1) the virus removal performance increases as the virus diameter increases, and 2) the recovery rate of proteins with molecular weights greater than 10,000 exceeds the practical level. This paper outlines the emergence of VF and its essential roles in the purification process of biological products, requirements for VF, phase separation studies for cuprammonium cellulose solution, comparison between Planova and other regenerated cellulose flat membranes made from other cellulose solutions, and the development of Planova. The superior properties of Planova can be attributed to its highly interconnected three-dimensional network structure. Furthermore, future trends in the VF field, the subject of this review, are discussed.

Crystalline structure analysis of all-cellulose nanocomposite films based on corn and wheat straws

Cellulose solution and nanocellulose were prepared from corn straw and wheat straw and then used to fabricate an all-cellulose nanocomposites film (ANF). The crystal structure (CS) of ANFs was analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR). Cellulose-I and cellulose-II were found to coexist within regenerated cellulose films (RCF) and ANFs. With the change of nanocellulose content, the proportions of cellulose-I and cellulose-II changed. Cellulose transformation was found to depend on the raw material and the preparation method. When cellulose solution was prepared from corn straw that had been extracted, the cellulose type tended to be transformed from cellulose-I to cellulose-II; the proportion of cellulose-I showed a tendency to increase when nanocellulose content exceeded 1.5%. When the dissolved cellulose had been treated by an acid-alkali method, the results did not follow a clear pattern. However, when cellulose solution was prepared from wheat straw, under extraction method, the cellulose type tended to transform from cellulose-I to cellulose-II; under acid-alkali method, cellulose-I did not follow a clear pattern with nanocellulose content. Though the small amount of nanocellulose can’t dominate the content of cellulose-I, it could cause an increase in disorder of the cellulose matrix.

The method for identification of mathematical models in two-factor pharmaceutical research

The methodical approach to solving problems of identification of mathematical models of pharmaceutical objects with two dependent quantitative factors has been considered; the total value of them is determined by the quantitative composition of the mixture and is fixed at a definite level.Aim. To determine the optimal algorithm for processing experimental data using the minimum number of experiments according to the plan 22to establish an adequate mathematical description of research at the technological stage.Materials and methods. Such materials as potato starch (quantitative factor x1) and the microcrystalline cellulose solution (quantitative factor x2) were used. The content of excipients should be 54 % of the total mass. Based on a priori data the content of potato starch x1 should be in the range from 45 to 50 % of the total amount (45 ≤ x1 ≥ 50), and x2 characterizes an aqueous solution of microcrystalline cellulose with a concentration in the range from 2 to 5 % (2 ≤ x2 ≥ 5). The least squares method was applied to determine the coefficients of the regression equations. During our research the Mathcad computer environment (MathSoft Ins., USA) was used.Results. To reduce the number of solutions and make the right decision it is necessary to have a reliable source of information and impose the appropriate restrictions based on a priori data and practical experience of the researcher. Conclusions. The studies have shown that to identify mathematical models the analysis of the main (final) effects of the interaction of factors is effective, it is also expedient to interpret this interaction based on the interpretation of the dependences of objective functions on each factor provided that the variable is fixed at the minimum and maximum levels of variation.

Self-healing Co3O4@Fe3O4/cellulose Blend Membranes Efficient Degrade Perfluorooctanoic Acid in the Visible Light-driven Photo-fenton System

Co3O4@Fe3O4/cellulose was synthesized by in-situ self-assembly strategy coating rod-like MOF-derived Fe3O4 with Co3O4 nanoparticles and blending with cellulose solution, further applied in the visible light-driven photo-Fenton system for PFOA degradation. In addition, Co3O4@Fe3O4/cellulose/Vitrimer was obtained to explore the application of self-healing property in photo-Fenton filed and the result turned out to be good self-healing capacity for small cracks. In comparison, Co3O4@Fe3O4/cellulose can degrade around 94.5% PFOA within 180 min in reaction system, which shows better degradation capacity than others catalyst. Moreover, Co3O4@Fe3O4/cellulose was reused by rinsing with ultra-pure water and the degradation capacity was still 80.4% after five cycles. In this system, the results of Electron paramagnetic resonance analysis (EPR) and scavenger experiment suggested that PFOA degradation was a co-dependent mechanism via photogenerated electrons, photogenerated holes (h+) and various radical species, rather than a single active constituent. The degradation pathway of PFOA also was proposed based on UHPLC-MS analysis.

Comparison of Cellulose Dissolution Behavior by Alkaline and Sulfuric Acid Solvents and Their Films’ Physical Properties

Three alkaline mixtures (NaOH/thiourea, NaOH/urea/thiourea, NaOH/urea/ZnO) and sulfuric acid were used at low temperatures as cellulose solvents, and their cellulose solubility and films’ physical properties for bleached chemical wood pulps and cotton linter were compared. Their degree of polymerization (DP) was controlled to 600–800 before dissolution. Among the alkaline solvents, NaOH/urea/ZnO gave the film the highest tensile strength and stretch. When compared to sulfuric acid, NaOH/urea/ZnO gave lower strength properties but higher crystallinity indices in the films. While alkaline solvents could not dissolve the high DP cellulose (DP ~ 2000), sulfuric acid could dissolve the high DP cellulose at below zero Celsius temperature, and the strength properties of the films were not much different from that of the low DP one. It appeared that the low-temperature sulfuric acid treatment did away with the cellulose’s DP controlling stage; it decreased cellulose DP very quickly for the high-DP cellulose at the initial stage, and as soon as the cellulose DP reached a DP low enough for dissolution, it began to dissolve the cellulose to result in stable cellulose solution.

Proton Conductive, Low Methanol Crossover Cellulose-Based Membranes

This work describes the development of sulfated cellulose (SC) polymer and explores its potential as an electrolyte-membrane for direct methanol fuel cells (DMFC). The fabrication of our membranes was initiated by the preparation of the novel sulfated cellulose solution via controlled acid hydrolysis of microcrystalline cellulose (MCC). Ion-conductive crosslinked SC membranes were prepared following a chemical crosslinking reaction. SC solution was chemically crosslinked with glutaraldehyde (GA) and cured at 30 °C to produce the aforementioned membranes. Effects of GA concentration on methanol permeability, proton conductivity, water uptake and thermal stabilities were investigated. The crosslinking reaction is confirmed by FTIR technique where a bond between the primary OH groups of cellulose and the GA aldehyde groups was achieved, leading to the increased hydrophobic backbone domains in the membrane. The results show that the time of crosslinking reaction highly affects the proton conduction and methanol permeability. The proton conductivity and methanol crossover (3M) of our GA crosslinked SC membranes are 3.7 × 10−2 mS cm−1 and 8.2 × 10−9 cm2 s−1, respectively. Crosslinked sulfated cellulose films have lower ion conductivity than the state-of-the-art Nafion (10.2 mS cm−1); however, the methanol crossover is three orders of magnitude lower than Nafion membranes (1.0 × 10−5 cm2 s−1 at 1 M). Such biofilms with high methanol resistivity address the major hurdle that prevents the widespread applications of direct alcohol fuel cells.