Cellulose acetate membranes loaded with combinations of tetraphenylporphyrin, graphene oxide and Pluronic F-127 as responsive materials with antibacterial photodynamic activity.

The development of polymeric fabrics with photoinduced antibacterial activity is important for different emerging applications, ranging from materials for medical and clinical practices to disinfection of objects for public use. In this work we prepared a series of cellulose acetate membranes, by means of phase inversion technique, introducing different additives in the starting polymeric solution. The loading of 5,10,15,20-tetraphenylporphyrin (TPP), a known photosensitizer, was considered to impart antibacterial photodynamic properties to the produced membranes. Besides, the addition of a surfactant (Pluronic F-127) allowed to modify the morphology of the membranes whereas the use of graphene oxide (GO) enabled further photo-activated antibacterial activity. The three additives were tested in various concentrations and in different combinations in order to carefully explore the effects of their mixing on the final photophysical and photodynamic properties. A complete structural/morphologycal characterization of the produced membranes has been performed, together with a detailed photophysical study of the TPP-containing samples, including absorption and emission features, excited state lifetime, singlet oxygen production, and confocal analysis. Their antibacterial activity has been assessed in vitro against S. aureus and E. coli, and the results demonstrated excellent bacterial inactivation for the membranes containing a combination of the three additives, revealing also a non-innocent role of the membrane porous structure in the final antibacterial capacity.

Cellulose Acetate Fabrics Loaded with Rhodamine B Hydrazide for Optical Detection of Cu(II).

In this work, different materials were fabricated from cellulose acetate, loaded with rhodamine B hydrazide and tested as Cu(II) optical sensor. We prepared membranes displaying a sub-micron porous structure using the phase inversion technique, clusters of fibers with varying diameter depending on the preparation procedure using electrospinning, and casted films presenting a smooth non porous structure. Loading of rhodamine B hydrazide on the fabrics after their production was found to be the best procedure to ensure the stability of the dye in the polymeric materials. Absorption and emission analysis of the solid substrates revealed the presence of the dye on the porous fabrics and allowed to choose the most suited materials and loading conditions to test their response towards Cu(II) ions. Reaction of the loaded rhodamine B hydrazide with Cu(II) was confirmed by absorption and emission spectroscopies and by confocal fluorescence imaging, through detection of the product rhodamine B. The results point to promising sensing applications of the prepared composite materials.

Chitosan-based delivery systems for plants: A brief overview of recent advances and future directions.

Chitosan has been termed as the most well-known among biopolymers, receiving widespread attention from researchers in various fields mainly, agriculture, food, and health. Chitosan is a deacetylated derivative of chitin, mainly isolated from waste shells of the phylum Arthropoda after their consumption as food. Chitosan molecules can be easily modified for adsorption and slow release of plant growth regulators, herbicides, pesticides, and fertilizers, etc. Chitosan as a carrier and control release matrix that offers many benefits including; protection of biomolecules from harsh environmental conditions such as pH, light, temperatures and prolonged release of active ingredients from its matrix consequently protecting the plant's cells from the hazardous effects of burst release. In the current review, tends to discuss the recent advances in the area of chitosan application as a control release system. Also, future recommendations will be made in light of current advancements and major gaps.

Current advancements in chitosan-based film production for food technology; A review.

Chitosan is obtained from chitin, which could be considered to be the most abundant polymer after cellulose. Owing to these properties, chitosan alone or chitosan-based composite film production is attaining huge attention in terms of applications from researchers and industrialists coming from divergent fields. To enhance the biological (mainly antimicrobial and antioxidant) and physiological (mainly mechanical, thermal and barrier) attributes of the chitosan-based films, a vast medley of plant extracts and supporting polymers has been blended into chitosan films. Considering the up to date literature reports based on chitosan film production and applications, it can be stated that still, the research ratio is low in this field. Chitosan blend/composite films with specific properties (superhydrophobicity, excellent mechanical strength, acceptable barrier properties) can be produced only for specific applications in food technology. In the current review, we tried to summarize the advancements made in the last 5-7 years in the field of chitosan film technology for its application in the food industry.

Nanostructured mesoporous silica: influence of the preparation conditions on the physical-surface properties for efficient organic dye uptake.

A series of ordered mesoporous silica such as MCM-41, SBA-3 and SBA-15, in addition to silica micro- (SM) and nano- (SN) mesoporous particles, were prepared. The preparation conditions were found to greatly influence the physical-surface properties including morphological structure, porosity, particle size, aggregate average size, surface area, pore size, pore volume and zeta potential of the prepared silica, while the chemical structure, predicted from FT-IR spectra, and the diffraction patterns, predicted from wide-angle X-ray diffraction spectra, were identical. Surface areas of approximately 1500, 1027, 600, 552 and 317 m2 g-1, pore volumes of 0.93, 0.56, 0.82, 0.72 and 0.5 cm3 g-1, radii of 2.48, 2.2, 5.66, 6.6 and 8.98 nm, average aggregate sizes of 56, 65.4, 220.9, 73, 61.1 and 261 nm and zeta potential values of -32.8, -46.1, -26.3, -31.4 and -25.9 mV were obtained for MCM-41, SBA-3, SBA-15, SN and SM, respectively. Methylene blue dye uptake capacity of the prepared silica types was investigated using the batch technique and, in addition, the most effective material was further studied by the column flow system. The kinetics and isotherms of the uptake process were studied. The morphological structure, surface area, pore radius and zeta potential values were the most correlated factors.

Aquatic environmental risk assessment of chitosan/silver, copper and carbon nanotube nanocomposites as antimicrobial agents.

Despite the potential antimicrobial and water purification benefits of chitosan-based nanocomposites, there are growing concerns regarding the hazards of leached nanoparticles (NPs) to the in-contact circumference. The antibacterial performance of the nanocomposites of chitosan with silver and copper NPs and carbon nanotubes was assessed with an emphasis on their impact on fish health. The minimal inhibitory concentrations of each preparation and the growth curves of Aeromonas hydrophila exposed to different nanocomposites were measured. Five groups of Oreochromis niloticus were exposed to chitosan nanocomposites for three weeks. A combination of a low concentration of the NPs in the chitosan matrix improved their antimicrobial properties. However, aqueous exposure to these materials still had hazardous effects on fish health. Experimental groups of O. niloticus exposed to these nanocomposites exhibited oxidative stress, tissue DNA fragmentation and higher expression of pro-inflammatory and immune-related genes such as TNF-α and IL1ß. Various pathological tissue alterations were observed in gills, liver, spleen and intestine. Exposure to some of the prepared nanocomposites led to significant DNA damage in hepatic cells with a marked increase in the apoptotic index.

Preparation and immunological evaluation of inactivated avian influenza virus vaccine encapsulated in chitosan nanoparticles.

Efficacy maximization of inactivated avian influenza vaccine using safe adjuvants was investigated. Chitosan nanoparticles were prepared by ionic gelation method with average size of 150 nm and their Zeta potential was 11.5 mV. After encapsulation of avian influenza vaccine, the average size was 397 nm and Zeta potential was 4.29 mV. The highest HI antibody titer results were shown in chicken group vaccinated with inactivated avian influenza virus AIV-chitosan followed by the group vaccinated with inactivated AIV-chitosan nanoparticles then the group vaccinated with oil inactivated AIV vaccine, on using chicken antigen at 2 weeks post second vaccination. Upon using duck antigen, the highest HI antibody titers were shown in chicken group vaccinated with inactivated AIV oil emulsion vaccine followed by chicken group vaccinated with AIV-chitosan nanoparticles then the group vaccinated with AIV-chitosan. Chicken in the group vaccinated with AIV-chitosan nanoparticles induced the best results of lymphocyte proliferation assay. The results of phagocytic activity percentage and phagocytic index of AIV-chitosan nanoparticles and AIV-chitosan groups at 3 days post first vaccination were increased significantly in comparison with other groups, whereas at 14 days post first vaccination, group vaccinated with AIV-chitosan nanoparticles showed significant increase in phagocytic activity percentage and phagocytic index.

Multifunctional nanocomposites of chitosan, silver nanoparticles, copper nanoparticles and carbon nanotubes for water treatment: Antimicrobial characteristics.

Multifunctional nanocomposites of chitosan with silver nanoparticles, copper nanoparticles and carbon nanotubes either as bi- or multifunctional nanocomposites were prepared. Change in the overall morphology of the prepared nanocomposites was observed; carbon nanotubes, Ag NPs and Cu NPs are distributed homogeneously inside the polymer matrix individually in the case of the bi-nanocomposites while a combination of different dimensional shapes; spherical NPs and nanotubes was observed in the multifunctional nanocomposite. Multifunctional nanocomposites has a higher antimicrobial activity, in relative short contact times, against both Gram negative and Gram positive bacteria; E. coli, Staphylococcus aureus; respectively in addition to the fungal strain; Aspergillus flavus isolated from local wastewater sample. The nanocomposites are highly differentiable at the low contact time and low concentration; 1% concentration of the multifunctional nanocomposite is very effective against the tested microbes at contact time of only 10min.