ABSTRACT
Bacterial cellulose (BC) holds several unique properties such as high water retention capability, flexibility, biocompatibility, and high absorption capacity. All these features make it a potential material for wound healing applications. However, it lacks antibacterial properties, which hampers its applications for infectious wound healings. This study reported BC-based dressings containing ε-polylysine (ε-PL), cross-linked by a biocompatible and mussel-inspired polydopamine (PDA) for promoting infectious wound healing. BC membranes were coated with PDA by a simple self-polymerization process, followed by treating with different contents of ε-PL. The resulted membranes showed strong antibacterial properties against tested bacteria by both in vitro and in vivo evaluations. The membranes also exhibited hemocompatibility and cytocompatibility by in vitro investigations. Moreover, the functionalized membranes promoted infected wound healing using Sprague-Dawley rats as a model animal. A complete wound healing was observed in the group treated with functionalized membranes, while wounds were still open for control and pure BC groups in the same duration. Histological investigations indicated that the thickness of newborn skin was greater and smoother in the groups treated with modified membranes in comparison to neat BC or control groups. These results revealed that the functionalized membranes have great potential as a dressing material for infected wounds in future clinical applications.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Bandages , Cellulose/chemistry , Polylysine/therapeutic use , Staphylococcal Skin Infections/drug therapy , Wound Healing/drug effects , Animals , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/toxicity , Cellulose/toxicity , Escherichia coli/drug effects , Indoles/chemistry , Indoles/therapeutic use , Indoles/toxicity , Male , Mice , Microbial Sensitivity Tests , NIH 3T3 Cells , Polylysine/analogs & derivatives , Polylysine/toxicity , Polymers/chemistry , Polymers/therapeutic use , Polymers/toxicity , Rats, Sprague-Dawley , Skin/drug effects , Skin/pathology , Staphylococcal Skin Infections/pathology , Staphylococcus aureus/drug effects , Wound Infection/drug therapy , Wound Infection/pathologyABSTRACT
The oil/water (o/w) separation is a global challenge because of the increasing water contamination by oil spill accidents, and oil-containing wastewater produced by food, textile, and petrochemical industries. In this study, we have developed bacterial cellulose (BC) based superhydrophilic/underwater superoleophobic (SUS) membrane for o/w separation. The membrane was designed through a facile method by blending BC nanofibers with silica microparticles (SiO2-MPs), which was further modified by bio-inspired polydopamine (PDA) coatings. The composite membrane exhibited SiO2-MPs dependent o/w separation with a high separation efficiency of >99.9 % and a high flux rate of â¼10,660 Lm-2 h-1 while applying a small negative pressure (0.3-0.5 bar). The membrane with different content of SiO2-MPs also showed the potential to separate oil-in-water emulsion with the highest oil rejection of 98.2 % and the highest flux rate of â¼1250 Lm-2 h-1 on an ultra-low pressure <0.1 bar. Moreover, the membrane showed antifouling properties, recyclability, and stability in harsh conditions.
Subject(s)
Bacteria/metabolism , Cellulose/chemistry , Oils/chemistry , Wastewater/chemistry , Water/chemistry , Hydrogen-Ion Concentration , Hydrophobic and Hydrophilic Interactions , Indoles/chemistry , Materials Testing , Membranes, Artificial , Nanofibers/chemistry , Polymers/chemistry , Reproducibility of Results , Silicon Dioxide/chemistry , Spectroscopy, Fourier Transform Infrared , Water Purification/methodsABSTRACT
Bacterial cellulose (BC) is a substrate material with high purity and robust mechanical strength, but due to its small pore size and relatively expensive price, it is restricted as an oil-/water separation membrane. In this study, cheaper plant cellulose needle-leaf bleached kraft pulp (NBKP) was added to BC to increase the pore size of the composite membrane, and a superhydrophobic/superoleophilic membrane was prepared for oil-/water separation. The modified membrane surface displayed a petal-like micro-structure and a water contact angle (WCA) of 162.3°, while the oil contact angle was decreased to 0°. What's more, the membrane exhibited excellent oil-/water separation under gravity, recyclability, and a separation efficiency (>95 %), and it was both pH and salt resistant. The membrane also remained durably hydrophobic after 10 separation cycles. And the separation methodology is expected to be highly energy-efficient.
Subject(s)
Cellulose/chemistry , Gluconacetobacter xylinus/metabolism , Gravitation , Green Chemistry Technology/methods , Hydrophobic and Hydrophilic Interactions , Membranes, Artificial , Oils/chemistry , Polysaccharides, Bacterial/chemistry , Water/chemistry , Hydrogen-Ion Concentration , Lignin/chemistry , Plant Leaves/chemistry , Polysaccharides/chemistry , Porosity , Tensile StrengthABSTRACT
Komagataeibacter xylinus has received increasing attention as an important microorganism for the conversion of several carbon sources to bacterial cellulose (BC). However, BC productivity has been impeded by the lack of efficient genetic engineering techniques. In this study, a lambda Red and FLP/FRT-mediated site-specific recombination system was successfully established in Komagataeibacter xylinus. Using this system, the membrane bound gene gcd, a gene that encodes glucose dehydrogenase, was knocked out to reduce the modification of glucose to gluconic acid. The engineered strain could not produce any gluconic acid and presented a decreased bacterial cellulose (BC) production due to its restricted glucose utilization. To address this problem, the gene of glucose facilitator protein (glf; ZMO0366) was introduced into the knockout strain coupled with the overexpression of the endogenous glucokinase gene (glk). The BC yield of the resultant strain increased by 63.63-173.68%, thus reducing the production cost.
Subject(s)
Bacteria/genetics , Cellulose/genetics , DNA Nucleotidyltransferases/genetics , Gluconacetobacter xylinus/genetics , Recombination, Genetic/genetics , Carbon/metabolism , Gluconates/metabolism , Glucose/geneticsABSTRACT
An effective hybrid cuckoo search algorithm (CS) with improved shuffled frog-leaping algorithm (ISFLA) is put forward for solving 0-1 knapsack problem. First of all, with the framework of SFLA, an improved frog-leap operator is designed with the effect of the global optimal information on the frog leaping and information exchange between frog individuals combined with genetic mutation with a small probability. Subsequently, in order to improve the convergence speed and enhance the exploitation ability, a novel CS model is proposed with considering the specific advantages of Lévy flights and frog-leap operator. Furthermore, the greedy transform method is used to repair the infeasible solution and optimize the feasible solution. Finally, numerical simulations are carried out on six different types of 0-1 knapsack instances, and the comparative results have shown the effectiveness of the proposed algorithm and its ability to achieve good quality solutions, which outperforms the binary cuckoo search, the binary differential evolution, and the genetic algorithm.
Subject(s)
Algorithms , Models, Theoretical , Problem Solving , Computer SimulationABSTRACT
OBJECTIVE: To develop a quantitative method for determination of the total organic acids and salicyclic acid in the extract of Radix Isatidis. METHOD: The total organic acids were determined by acid-base titration and the salicylic acid was determined by HPLC. RESULT: It was shown that contents of total organic acids and salicylic acid in the extract of Radix Isatidis were 13.0% and 0.22%, respectively. CONCLUSION: The method can control the quality of this extract effectively and accurately.
