Synthesis and characterization of mussel-inspired nanocomposites based on dopamine-chitosan-iron oxide for wound healing: In vitro study.

There are many challenges faced the soft tissue adhesives in the medical application field. For example, there is a limited effective binding between the medical adhesive and different types of soft tissues. Chitosan (CS) and dopamine (DA) were used as structural units for synthesizing nanocomposites utilized as a wet tissue adhesive. To produce dopamine-chitosan-iron oxide nanocomposites (DA-CS-Fe3O4 NCs), DA was loaded onto chitosan-iron oxide nanocomposites. The nanocomposites have been prepared using ionic gelation method under vigorous homogenization and characterized by different techniques. Fourier-transform infrared spectroscopy (FTIR) have shown that DA-CS- Fe3O4 NCs could attach to the tissue through two possible functional groups, namely, the catechol and amine groups. The results of in vitro scratch wound-healing assay suggested that the prepared DA-CS- Fe3O4 NCs facilitate cell migration (the wound-closure percentage reached 96% at 72 h). All experimental results confirm that DA-CS- Fe3O4 NCs are strongly recommended for use as a soft medical tissue adhesive in wound healing and surgeries such as vascular surgery. In addition, the results of the whole blood clotting, antibacterial assessment, live and dead assay, cytotoxicity test, and wound-healing assay indicate that DA-CS-Fe3O4 NCs can be used as a multifunctional biomedical adhesive.

Investigation of Biological and Prooxidant Activity of Zinc Oxide Nanoclusters and Nanoparticles.

Zinc oxide (ZnO) nanomaterials offer some promising antibacterial effects. In this study, a new form of ZnO is synthesized, named ZnO nanocluster bars (NCs). Herein, ZnO NCs, ZnO nanoparticles (NPs), ZnO coated with silica (ZnO-SiOA, ZnO-SiOB), and SiO2 NPs were prepared, characterized, and their antimicrobial and prooxidant activity were tested. The prooxidant activity of all nanomaterials was studied according to free-radical oxidation reactions (pH 7.4 and pH 8.5) in chemiluminescent model systems. Each form of new synthesized ZnO nanomaterials exhibited a unique behavior that varied from mild to strong prooxidant properties in the Fenton`s system. ZnO NPs and ZnO NCs showed strong antibacterial effects, ZnO-SiOA NPs did not show any antibacterial activity representing biocompatibility. All tested NMs also underwent oxidation by H2O2. ZnO NCs and ZnO NPs exhibited strong oxidation at pH 8.5 in the O2-. generating system. While, SiO2, ZnO-SiOA andZnO-SiOB possessed pronounced 60-80% antioxidant effects, SiO2 NPs acted as a definitive prooxidant which was not observed in other tests. ZnO NCs are strong oxidized, assuming that ZnO NCs provide a slower release of ZnO, which leads to having a stronger effect on bacterial strains.  Thus, ZnO NCs are an important antibacterial agent that could be an emergent replacement of traditional antibiotics.

Evaluation of cell-mediated immunity of E.coli nanovaccines in chickens.

Nanovaccine is a revolutionary type of immunizations for various diseases that is simple to manufacture and administer. As a result, we are working to develop innovative nanovaccines against E. coli, which is capable of causing disease both inside and outside of its predilection sites, causing respiratory and systemic disease (colibacillosis).Colibacillosis is a global disease that significantly affects poultry production. The present study aims to evaluate in vivo cell-mediated immunity against a chitosan-nanovaccine from E. coli serogroups O1 and O78 to aid in limiting colibacillosis in chicken. Two hundred specific pathogen-free (SPF) three weeks old broiler chickens were used and divided into five groups: the first group inoculated with the outer membrane and flagellar antigen (OF), the second group inoculated with chitosan capsulated-outer membrane protein-flagellar antigen (CSC-O-F), the third group inoculated with chitosan loaded-outer membrane protein-flagellar antigen (CSL-O-F), the fourth group was vaccinated with (CSL-O-F-M) adjuvanted with Montanide ISA 71 RVG, and the fifth group was left as unvaccinated control. The immune response was measured by ELISA, lymphocyte proliferation test, and challenge test. The duration of immunity was also studied. The CSL-O-F-M had the highest antibody titer in an ELISA test using the O1 strain, and the CSC-O-F had the highest antibody titer in an ELISA test using the O78 strain. For both O1 and O78 strains, the CSL-O-F-M had the strongest cell-mediated immune response, which was validated by the challenge test and duration study. We recommend producing nanovaccines (CSL-O-F-M) from E.coli O1 and O78 strains as a new manufacturing vaccine based on the demonstrated results. Because it produces highly effective humoral and cell-mediated immune responses, this novel vaccine may be useful in reducing the risk of colibacillosis.

Silica-coated graphene compared to Si-CdSe/ZnS quantum dots: Toxicity, emission stability, and role of silica in the uptake process for imaging purposes.

Quantum dots (QDs) present a special type of nanocrystals (NCs) due to their unique optical and chemical properties. While cadmium-based QDs (Cd-QDs) have the most favorable physicochemical properties, their toxicity, instability in the aqueous phase, and loss of brightness at high temperature are some of the obstacles that prevent the wide use of Cd-QDs. Carbon-based QDs as graphene quantum dots (GQDs) represent a very promising biocompatible replacement. In the present work, we mainly focus on comparing the efficiency and uptake of GQDs and Cd-QDs for fluorescent imaging purposes and studying the effect of growing silica shell on the emission and the uptake of QDs inside living human and bacterial cells. Graphene and CdSe/ZnS QDs were prepared and encapsulated in silica to increase their emission and uptake by living cells. Moreover, we studied their photostability and cytotoxicity. The Prepared G-Si QDs showed good emission inside the cytoplasmic portion of the liver hepatocellular carcinoma cell line (HepG2) and Bacillus subtilis (B. subtilis), but they revealed lower photoluminescence (PL) intensity compared to Si-CdSe/ZnS NCs although G-Si QDs are advantageous in other aspects, i.e. possess lower toxicity and higher stability with temperature variations.

Impact of foliar spray of zinc oxide nanoparticles on the photosynthesis of Pisum sativum L. under salt stress.

This study investigates the impacts of zinc oxide nanoparticles: bare (ZnO NPs) and ZnO NPs coated with silicon shell (ZnO-Si NPs), on Pisum sativum L. under physiological and salt stress conditions. The experimental results revealed that the foliar spray with ZnO-Si NPs and 200 mg/L ZnO NPs did not influence the stomata structure, the membrane integrity, and the functions of both photosystems under physiological conditions, while 400 mg/L ZnO-Si NPs had beneficial effects on the effective quantum yield of photosystem II (PSII) and the photochemistry of photosystem I (PSI). On the contrary, small phytotoxic effects were registered after spraying with 400 mg/L ZnO NPs accompanied by stimulation of the cyclic electron flow around PSI and an increase of the non-photochemical quenching (NPQ). The results also showed that both types of NPs (with exception of 400 mg/L ZnO NPs) decrease the negative effects of 100 mM NaCl on the photochemistry of PSI (P700 photooxidation) and PSII (qp, Fv/Fm, Fv/Fo, ΦPSII, Φexc), as well as on the pigment content, stomata closure and membrane integrity. The protective effect was stronger after spraying with ZnO-Si NPs in comparison to ZnO NPs, which could be due to the presence of Si coating shell. The role of Si shell is discussed.

A novel synthesis of a chlorophyll b-gold nanoconjugate used for enhancing photodynamic therapy: In vitro study.

Chlorophyll, the essential green pigment in plants, is considered a promising natural photosensitizer (PS) for photodynamic therapy (PDT). However, it suffers from lower stability in the physiological conditions that depress its efficacy in the PDT. The combination of nanotechnology and PDT is becoming a promising approach to combat tumors. Gold nanoparticles (Au NPs), for example, are proposed as suitable carriers that can increase chlorophyll stability when conjugating together. In the present work, the impact of Au NPs conjugation in enhancing Chlorophyll b (Chl b) efficiency in the PDT of cancer cells has been emphasized. A chemical method using a natural product synthesized a novel Chlorophyll b-gold nanoparticles nanoconjugate (Chl b-Au NCs). The synthesized Chl b-Au NCs were characterized via UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Laser-Induced Fluorescence (LIF), Zeta potential, Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). Chl b is characterized by a formyl group (CHO) which is absent in Chl a. This group leads to the formation of an electrostatic reaction between the positive charge of Chl b and the negative charge present on the surface of the gold nanoparticles. Moreover, Chlorophyll b loading on the biosynthesized gold nanoparticles (Au NPs) increases its photostability. The efficiency of the PDT was then studied on the MCF7 and the HepG2 cells using this conjugation. As a result, the prepared Chl b-Au NCs showed low dark toxicity, excellent photostability under laser irradiation of wavelength 650 nm, in addition to a significantly high PDT efficacy against tumor cells in vitro. This is due to the enhanced cellular uptake and the high reactive oxygen species (ROS) production upon laser irradiation. Therefore, the designed Chl b-Au NCs could be a photo-therapeutic agent for enhancing cancer therapy in future applications.

Potential improvement of the immune response of chickens against E. coli vaccine by using two forms of chitosan nanoparticles.

Colibacillosis disease has an important economic impact on poultry production worldwide. It is one of the most common causes of mortality in commercial layer and breeder chickens. Avian pathogenic Escherichia coli (APEC) is the main cause of this disease. Nanoparticles have been widely used in vaccine design as both adjuvants and antigen delivery vehicles. The present study aimed to produce an efficient vaccine from E. coli serogroups O1 and O78 to help in controlling colibacillosis in chicken using two forms of chitosan (CS) and ascorbate chitosan (AsCS) nanoparticles. Nanovaccines has been prepared through loading and encapsulation of outer membrane and flagellar antigen on CS and AsCS nanoparticles with loading efficiency 86, 63,55, 48% for CS-loaded-, Cs-capsulated-, AsCS-loaded- and AsCS-capsulated-E. coli Antigen, respectively. Two hundred specific pathogens free (SPF) 3-weeks old broiler chickens were used and divided into four groups to investigate the immune response of nanovaccines. The immune response was measured by the microagglutination, ELISA, and challenge test. From results, it could be concluded that generally adding chitosan NPs is capable of improving vaccine efficacy via the induction of strong immunity. Moreover, we recommend the production of the nanovaccine CS-capsulated -antigen from E. coli O1 and O78 serotypes to be used as a potent vaccine to aid in controlling colibacillosis. Also, the ascorbate chitosan is a great alternate for the initiation of a potent immune response in critical infection cases.

Photothermal versus photodynamic treatment for the inactivation of the bacteria Escherichia coli and Bacillus cereus: An in vitro study.

The widespread occurrence of microbial pathogens, including multidrug-resistant (MDR) bacteria, has ignited research efforts to discover alternative strategies to combat infections in patients. Recently, photodynamic therapy (PDT) and photothermal therapy (PTT) have been proposed for the inactivation of pathogens. Although PDT and PTT are very promising antipathogenic tools, further effort is needed to determine their real impact on pathogens apart from the effects of individual elements involved in the photodynamic/photothermal processes, i.e., light, photosensitizers (PSs), and nanoparticles. Accordingly, in the current study, toluidine blue O (TBO) and gold nanoparticles (GNP) were used as generators of reactive oxygen species (ROS) and hyperthermia in the presence of light, respectively. Escherichia coli (E. coli) and Bacillus cereus (B. cereus) bacteria were chosen as examples of gram-negative and gram-positive bacteria, respectively. Before the bactericidal activity of PDT was assessed, the aggregation of TBO and its effect on the growth of both strains of bacteria were studied. Additionally, E. coli and B. cereus were exposed to a range of doses of 633 nm helium-neon laser light to investigate its effect. In a separate set of experiments, the bactericidal activity of PTT was assessed after the effects of GNP and green light (530 nm) had been assessed. The results showed that PDT and PTT should be considered useful tools for bacterial eradication even when the light, PSs, and nanoparticles are each used at doses safe for bacterial growth. Moreover, different photodynamic responses were observed for E. coli and B. cereus, and light from a 633 nm laser and a 530 nm light-emitting diode (LED) showed disparate responses when applied alone to both bacteria.

Ecotoxicology impact of silica-coated CdSe/ZnS quantum dots internalized in Chlamydomonas reinhardtii algal cells.

The use of quantum dots (QD) in various medical and industrial applications may cause these nanoparticles to leak into waterways and subsequently enter the food chain. Therefore, if we intend to use QD, we must first know their potential environmental implications. In this work, cadmium selenide/zinc sulfide core/shell QD were synthesized, and then, biocompatible, water-dispersed QD were coated with silica (Si-QD). The QD were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX), and UV-Vis absorption analysis, which revealed that these surface-engineered QD have a highly crystalline, homogeneous spherical shape measuring approximately 25 nm. The cytotoxicity of the nanoparticles in the green algae Chlamydomonas reinhardtii was studied by incubating the algae cells with Si-QD and determining the optical density of algal cell culture, cell counts, and cells sizes by microflow cytometry. These measurements indicated that Si-QD are biocompatible up to a concentration of 25 ng/ml. Finally, the cellular uptake of Si-QD into C. reinhardtii was monitored by confocal laser scanning microscopy (CLSM). In conclusion, our results reveal that surface-engineered Cd-QD can penetrate the cells of aquatic organisms, which ensures a serious impact on the food chain and consequently the environment. On the other hand, the results also highlight a new potential method for bioremediation of Cd-QD by green algae, especially C. reinhardtii.