Effects of Hydrophobic Tail Length Variation on Surfactant-Mediated Protein Stabilization.

Recently, protein therapeutics have gained significant attention as a result of their enhanced selectivity and diminished side effects compared to traditional small-molecule drugs. Despite their advantages, protein formulations typically suffer from stability issues because of aggregation and denaturation during production and storage, often resulting in detrimental immune responses. Surfactants can be used to stabilize and protect proteins in solution by preventing protein adsorption onto interfaces or by forming protective structures in solution. Herein, a detailed structure-activity relationship study is described, demonstrating the role that hydrophobic tail length plays in surfactant-mediated stabilization of the model therapeutic protein IgG. The FM1000 series, originating from a surfactant scaffold that allows for easy structure modulation, was synthesized by a simple 2-step procedure. First, phenylalanine was acylated with a variety of acyl chlorides of differing lengths to yield n-acyl phenylalanine, which was then coupled to Jeffamine M1000, a polyethylene glycol-based amine, to yield the final surfactant. With this FM1000 series, it was observed that the 14 carbon-long tail surfactant (14FM1000) was optimal at preventing IgG aggregation compared to surfactants with tails that were longer or shorter. Using a combination of dynamic surface tensiometry and quartz crystal microbalance with dissipation, it was hypothesized that 14FM1000 was able to prevent IgG adsorption, and therefore aggregation, by adsorbing appreciably onto surfaces quickly. 14FM1000 had the fastest rate of initial adsorption compared to the other surfactants studied. Short-tail surfactants were slow to and did not adsorb appreciably onto surfaces, allowing IgG adsorption. Although long-tail surfactants were also slow to adsorb, allowing IgG to adsorb and aggregate, their equilibrium adsorption was strong. Additionally, 14FM1000 was the most reversibly adsorbed surfactant, likely improving its ability to desorb and adsorb quickly to transient surfaces, therefore protecting the IgG at each new hydrophobic surface and preventing aggregation. By understanding the structure-activity relationship between surfactants and protein stabilization, we move toward more efficient design of future surfactants increasing the stability and utility of important protein therapeutics.

Performance of an anaerobic membrane bioreactor in which granular sludge and dynamic filtration are integrated.

To alleviate the fouling of a filter, simple substrates, dynamic filtration, and granular sludge were applied in an anaerobic membrane bioreactor (AnMBR). The results showed that under a transmembrane pressure < 20 kPa, the filter flux ranged between 15 and 20 l (m-2 h)-1 for a period of 30 days. The flux was higher than the typical flux of AnMBRs with conventional membranes and most current dynamic filters. In addition, the low cost of the filter avoided the need for a higher flux. Moreover, a stable granular sludge bed, which consumed all volatile fatty acids, was maintained. A compact fouling/filtration layer formed on the filter, which contributed to low effluent chemical oxygen demand concentrations and turbidity. In addition, substrate scarcity in the filtration zone resulted in the evolution of diverse bacteria on the filter.

Preparation, characterization, and application of gallic acid-mediated photodynamic chitosan-nanocellulose-based films.

In this study, an active film composed of gallic acid (GA), chitosan (CS), and cellulose nanocrystals (CNC) was prepared using a solution casting method and synergistic photodynamic inactivation (PDI) technology. Characterization of the film showed that the CS-CNC-GA composite film had high transparency and UV-blocking ability. The addition of GA (0.2 %-1.0 %) significantly enhanced the mechanical properties, water resistance, and thermal stability of the film. The tensile strength increased up to 46.30 MPa, and the lowest water vapor permeability was 1.16 × e-12 g/(cm·s·Pa). The PDI-treated CS-CNC-GA1.0 composite film exhibited significantly enhanced antibacterial activity, with inhibition zone diameters of 31.83 mm against Staphylococcus aureus and 21.82 mm against Escherichia coli. The CS-CNC-GA composite film also showed good antioxidant activity. Additionally, the CS-CNC-GA1.0 composite film generated a large amount of singlet oxygen under UV-C light irradiation. It was found that using the CS-CNC-GA1.0 composite film for packaging and storage of oysters at 4 °C effectively delayed the increase in pH, total colony count, and lipid oxidation in oysters. In conclusion, the CS-CNC-GA composite film based on PDI technology has great potential for applications in the preservation of aquatic products.

Soft machining-induced surface and edge chipping damage in pre-crystalized lithium silicate glass ceramics.

Soft machining is a key procedure in fabrication of high-strength lithium-based silicate glass ceramic (LS) restorations. This paper reports on the diamond machining-induced surface and edge chipping damage in two pre-crystalized LS materials: pre-crystallized lithium metasilicate/orthophosphate glass ceramic (Pre-LS, IPS e.max CAD) and pre-crystallized zirconia-containing lithium metasilicate glass ceramic (Pre-ZLS, Vita Suprinity). Indentation techniques were used to measure the material mechanical properties. Soft machining was conducted using a robotic controlled apparatus mimicking dental CAD/CAM machining processes at different removal rates and enabling in-process force measurement. Machined surface roughness was assessed using 3D confocal optical profilometry in terms of the average and maximum surface heights. Scanning electron microscopy was used to assess diamond tool and machined surface and edge morphology. Soft machining of both materials was dominated by brittle fracture mixed with localized ductile flow. However, the higher brittleness index of Pre-ZLS than Pre-LS yielded higher degrees of machining-induced conchoidal fractures in Pre-ZLS in comparison with irregular fractures in Pre-LS. Thus, much larger surface roughness and deeper edge chipping damage were produced in Pre-ZLS than Pre-LS. Machining forces for Pre-ZLS were significantly smaller than Pre-LS, due to the lower machinability index associated with a complex relation of the mechanical properties as well as less debris adhesion for Pre-ZLS than Pre-LS. Further, increased material removal rates resulted in significantly increased machining forces, maximum surface roughness and fracture, and edge chipping damage in both Pre-ZLS and Pre-LS materials. Therefore, optimization of soft machining processes needs to be practiced to achieve accepted surface and edge quality at balanced removal rates.

Plastic leachates lead to long-term toxicity in fungi and promote biodegradation of heterocyclic dye.

The hazardous effects of plastic and plastic leachates on organisms, even bacteria, have attracted widespread attention, but only a limited effort has been devoted to explore the response of fungi to plastic leachate induced by light irradiation. Here, we performed plastic leaching experiments to obtain leachates from polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP), and optical properties of plastic leachates were analysed to determine the influence of light conditions and plastic materials on that. The effects of plastic leachates on the production of fungal enzyme and the biodegradation of heterocyclic dye by fungi were evaluated. Results indicated that the UV light greatly enhanced the release of leachates from the three plastics. Both plastic polymers and light irradiation affected the plastic-derived dissolved organic carbon (DOC) and their aromaticity, but the molecular weight of plastic leachates showed no dependency on light irradiation types, and PE was the easiest to photo age and leached more DOC. Plastic leachates had no dose-effect on the production of extracellular enzymes by fungi. PE leachates showed long-term toxicities to fungi, and no manganese peroxidase activities were detected after a 42-day incubation, while that of controls were up to 73.64 ± 8.81 U/L. However, the PE and PP leachates greatly promoted methylene blue degradation by the fungi, but PET leachates relieved the decolouration of methylene blue, probably because of the benzene ring structure in the PET monomer. Fusarium oxysporum had a stronger degradation ability than Phanerochaete chrysosporium. Our results indicate that plastic leachates can influence the production and secretion of fungi ligninolytic extracellular enzymes, and regulate the fungal degradation of heterocyclic dye.

Gene delivery of chitosan-graft-polyethyleneimine vectors loaded on scaffolds for nerve regeneration.

As an important transcription factor, c-Jun could upregulate growth factors expression in Schwann cells (SCs). Arginine-Glycine-Aspartate (RGD)-functionalized chitosan-graft-polyethyleneimine (RCP) gene vectors were prepared through the maleic anhydride & the carbodiimide methods, and electrostatically bound with c-Jun plasmids (pJUN), finally loaded on poly-L-lactic acid/silk fibroin parallel fiber films to fabricate nerve scaffold (RCP/pJUN-PSPF@PGA), which could locally deliver c-Jun plasmids into SCs via the mediation of RGD peptides, and upregulate the expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in SCs. After the scaffold was bridged in sciatic nerve defect, the delivery of c-Jun plasmids from RCP/pJUN-PSPF@PGA facilitated SCs to sustain the expressions of NGF, BDNF and vascular endothelial growth factor in the injury field, promoting myelination, axonal growth and microvascular generation and nerve regeneration, muscle reinnervation and functional recovery. These results suggested that RCP/pDNA-PSPF@PGA, as an effective gene delivery platform, could provide a local gene therapy to improve nerve regeneration.

Graphene enhanced transformation of lignin in laccase-ABTS system by accelerating electron transfer.

The degradation of lignin has attracted much attention since it represents approximately 30% of all non-fossil carbon sources and constitutes a sustainable bio-resource for fuels and aromatic derivatives. Here we investigated the degradation of lignin by laccase-catalysed reactions using 2,2'-Azino-bis(3-ethybenzothiazoline-6-sulfonic acid) (ABTS) as a mediator coupled with the carbon material graphene. Results indicated that there was a significant, two-fold, increase in the catalytic activity of lignin degradation in laccase-ABTS systems in the presence of graphene. Analysis suggested that the enhancement of lignin degradation could be attributed to graphene acting as an electron transfer conductor, thereby accelerating electron transfer, which facilitated the formation of intermediate oxidation states of ABTS and rendered the reactions between lignin and ABTS intermediates more efficient. This study could promote the development of novel enzymatic lignin degradation systems coupled with the carbon-based material graphene.

Magnetochromatic thin-film microplates.

A new type of magnetochromatic material is developed based on thin-film interference of microplates self-assembled from super-paramagnetic nanocrystals. Dynamic optical tuning can be achieved through orientational manipulation of free-standing super-paramagnetic thin-film microplates using external magnetic fields.

[Balloon inflating and cement filling for treatment of avascular necrosis of the femoral head: a three-dimensional infinite-element study].

OBJECTIVE: To evaluate the biomechanical changes of balloon inflating and cement filling in avascular necrosis of the femoral head using finite-element analysis. METHODS: The procedure of percutaneous balloon inflating and cement filling was simulated in fresh specimen of human femoral head. CT scan and three-dimensional reconstruction were used to establish the three-dimensional model of the femoral head. The physiological load was analyzed using three-dimensional finite element model to simulate the load and calculate stress on the hip during walking. Finite element analysis was performed on the avascular necrosis model and balloon inflating and bone cement filling model to measure the Von-Mises force at the top, neck and weight-bearing area of the femoral head. Another 8 fresh specimens of femoral head necrosis of human were obtained to stimulate balloon inflating and bone cement filling procedures, and the displacement of the femoral head under different loads was recorded before and after the procedures. RESULTS: After bone cement filling in the necrosis area, the load reduced significantly in the weight-bearing area of the femoral head, and the load distribution became more uniform at the femoral neck and the top of the head. The anti-deformation ability of the necrosis femoral head increased after bone cement filling. The infinite-element analysis and specimen biomedical test showed similar results. CONCLUSION: Percutaneous balloon inflating and bone cement filling in the necrosis area can change the biomechanics mechanism of the femoral head and neck, improve the supporting capacity under load, and prevent the progression of head collapse.

Characterization of pharmaceutical powder blends by NIR chemical imaging.

This study demonstrates the capabilities of NIR imaging as an effective tool for characterization of pharmaceutical powder blends. The powder system used in this small-scale powder blending study consists of acetaminophen (APAP, the model API), microcrystalline cellulose (MCC) and lactose monohydrate. Mixtures of these components were blended for different times for a total of ten time points (ten blending trials). Images collected from multiple locations of the blends were used to generate a qualitative description of the components' blending dynamics and a quantitative determination of both the blending end point and the distribution variability of the components. Multivariate analyses, including pure-component PCA and discriminate PLS, were used to treat the imaging data. A good correlation was observed between imaging results and a UV-Vis monitoring method for determining blend homogeneity. Score images indicated general trends of the distribution of blending constituents for all ten blending trials. The API distribution pattern throughout blending was detected and the API domain size for different blending trials was compared. Blending insights obtained from this study may be transferable to large scale powder blending. Blending process understanding obtained from this study has the potential to facilitate the optimization of blending process control in the future.