Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

Preparation and shape change of silver nanoparticles (AgNPs) loaded on the dialdehyde cellulose by in-situ synthesis method

With the improvement of medical and health care level in our society, the demand for antibacterial materials is increasing. In this work, we prepared the antibacterial materials by loading silver nanoparticles (AgNPs) on the dialdehyde cellulose (DAC) with in-situ synthesis method. DAC was prepared by pretreating cellulose fiber with sodium metaperiodate (NaIO₄) to convert the hydroxyl group into aldehyde group, and then reacted with silver nitrate (AgNO₃) to obtain AgNPs loaded on DAC. UV-Vis results show that the characteristic absorption peak of AgNPs at 428 nm appeared in the AgNPs-loaded-DAC. It was observed by SEM that the spherical AgNPs were distributed uniformly on the DAC surface without obvious flocculation. The color of DAC was not changed significantly, indicating that a small amount of AgNPs was loaded. In addition, sodium citrate (Na₃C₆H₅O₇) was added in the reaction of DAC and AgNO₃ and its effect on the formation of AgNPs was studied. The results demonstrated that the color of DAC turned deeper and finally dark yellow with reaction time extended. When the reaction time was 60 h, the spherical AgNPs were gradually grown and transformed into triangular prism on the DAC surface. The antibacterial properties of AgNPs showed inhibition zones of 4.90 mm and 7.35 mm (60 h) against Gram-negative (E. coli) and Gram-positive (S. aureus), respectively, which increased by 40.00% and 14.85% compared with spherical AgNPs (2.5 h) obtained without Na₃C₆H₅O₇. The research of AgNPs-loaded cellulose-based materials promotes the development prospect of new nano-antibacterial materials.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-022-04692-6.

Microcrystalline Cellulose-Supported Gold Nanoparticle Catalysts for Homocoupling of Phenylboronic Acids

A solid-grinding strategy for the large-scale synthesis of solid microcrystalline cellulose (MCC)-supported gold nanoparticle (NP) catalysts without using solvents and a sophisticated purification technique is reported. In contrast to typical solution-based methods, the deposition of high loading of gold NPs with greater uniformity on native MCC polymers without chemical modifications was achieved rapidly by manual grinding. The Fourier transform infrared (FT-IR) study revealed that the abundant hydroxyl functional groups present on the MCC support could effectively hold tiny gold NPs through hydrogen bonding between the -OH groups of MCC and gold NPs, thereby making the MCC-supported gold NPs stable heterogeneous catalysts. Thus, the Au/MCC catalyst exhibits higher catalytic activity and selectivity toward homocoupling of phenylboronic acids into corresponding biphenyls in water under air. Compared to other solid-supported gold NP catalysts, the MCC-supported gold catalysts showed greater catalytic activity and selectivity in the homocoupling of phenylboronic acids. The kinetics study on the homocoupling reaction catalyzed by Au/MCC reveals that the catalysts possess much lower apparent activation energy than the reported gold catalysts. Thus, the present sustainable approach may inspire more studies on the design of renewable biopolymer matrix-supported gold NPs in a large scale for heterogeneous catalysis.

Inorganic nanomaterials for fighting surface and airborne pathogens and viruses

Nowadays, the deadly viruses (including the latest coronavirus) and pathogens transmission became the major concern worldwide. Efforts have been made to combat with these fatal germs transmitted by the airborne, human-to-human contacts and contaminated surfaces. Thus, the antibacterial and antiviral materials have been widely researched. Meanwhile, the development of diverse nanomaterials with the antiviral traits provided several benefits to counter the threats from the surface and airborne viruses especially during the Covid-19 pandemic. Based on these facts, this paper overviewed the advantages of various nanomaterials that can disinfect and deactivate different lethal viruses transmitted through the air and surfaces. The past development, recent progress, future trends, environmental impacts, biocidal effects and prospects of these nanomaterials for the antiviral coating applications have been emphasized.

Bacterial cellulose-based magnetic nanocomposites: A review

Bacterial cellulose (BC) is a natural polymer that has unique and interesting structural, physical and chemical properties. These characteristics make it very attractive as a starting point for several novel developments in innovative research. However, the pristine BC lacks certain properties, in particular, magnetic property, which can be imparted to BC by incorporation of several types of magnetic nanoparticles. Magnetic nanocomposites based on BC exhibit additional magnetic functionality on top of the excellent properties of pristine BC, which make them promising materials with potential uses in various medical and environmental applications, as well as in advanced electronic devices. This review has compiled information about all classes of BC magnetic nanocomposites fabricated by various synthesis approaches and an overview of applications as well as improved features of these materials. A summary of the key developments of BC magnetic nanocomposites and emphasis on novel advances in this field is presented.

Polysaccharide-based nanocomposites and their applications

Polysaccharide nanocomposites have become increasingly important materials over the past decade. Polysaccharides offer a green alternative to synthetic polymers in the preparation of soft nanomaterials. They have also been used in composites with hard nanomaterials, such as metal nanoparticles and carbon-based nanomaterials. This mini review describes methods for polysaccharide nanocomposite preparation and reviews the various types and diverse applications for these novel materials.

Synthesis of Chitosan Oligomers/Propolis/Silver Nanoparticles Composite Systems and Study of Their Activity againstDiplodia seriata

The synthesis and characterization of composites of oligomeric chitosan with propolis extract which allow the incorporation of a third component (silver nanoparticles) are reported, together with their application in aqueous or hydroalcoholic solutions with a view to the formation of adhesive substances or nanofilms for the protection of vineyards against harmful xylophagous fungi. The antimicrobial properties of the association of the two biological products or those resulting from the incorporation of silver nanoparticles (NPs) are studied and discussed. The efficacy of the chitosan oligomers/propolis/silver NPs ternary system is assessedin vitroforDiplodiafungi. A preliminary study on the convenience of replacing propolis with gentisic acid is also presented.

Hybrid nanostructured Ag/ZnO decorated powder cellulose fillers for medical plastics with enhanced surface antibacterial activity

Hybrid inorganic-organic fillers based on nanostructured silver/zinc oxide decorations on micro-cellulose carrier particles were prepared by stepwise microwave assisted hydrothermal synthesis using soluble salts as precursors of silver and zinc oxide. Hexamethylenetetramine was used as precipitating agent for zinc oxide and reducing agent for silver. The inorganics covered all available surfaces of the cellulose particles with a morphology resembling a coral reef. Prepared particulate fillers were compounded to medical grade poly(vinyl chloride) matrix. Scanning electron microscopy and powder X-ray diffractometry were used to investigate the morphology and crystalline phase structure of fillers. The scanning electron microscopy was used for morphological study of composites. With respect to prospective application, the composites were tested on electrical and antibacterial properties. A small effect of water absorption in polymer composites on their dielectric properties was observed but no adverse effect of water exposure on prepared materials was manifested. Electrical conductivity of fillers and composites was measured and no influence of water soaking of composites was found at all. The surface antibacterial activity of prepared composites was evaluated according to the standard ISO 22196. Excellent performance against Escherichia coli and very high against Staphylococcus aureus was achieved.

Microwave-assisted incorporation of silver nanoparticles in paper for point-of-use water purification

This work reports an environmentally benign method for the in situ preparation of silver nanoparticles (AgNPs) in paper using microwave irradiation. Through thermal evaporation, microwave heating with an excess of glucose relative to the silver ion precursor yields nanoparticles on the surface of cellulose fibers within three minutes. Paper sheets were characterized by electron microscopy, UV-Visible reflectance spectroscopy, and atomic absorption spectroscopy. Antibacterial activity and silver release from the AgNP sheets were assessed for model Escherichia coli and Enterococci faecalis bacteria in deionized water and in suspensions that also contained with various influent solution chemistries, i.e. with natural organic matter, salts, and proteins. The paper sheets containing silver nanoparticles were effective in inactivating the test bacteria as they passed through the paper.

Silver-based nanoparticles induce apoptosis in human colon cancer cells mediated through p53

AIM

The authors have systematically investigated the anticancer potentiality of silver-based nanoparticles (AgNPs) and the mechanism underlying their biological activity in human colon cancer cells.

MATERIALS & METHODS

Starch-capped AgNPs were synthesized, characterized and their biological activity evaluated through multiple biochemical assays.

RESULTS

AgNPs decreased the growth and viability of HCT116 colon cancer cells. AgNP exposure increased apoptosis, as demonstrated by an increase in 4´,6-diamidino-2-phenylindole-stained apoptotic nuclei, BAX/BCL-XL ratio, cleaved poly(ADP-ribose) polymerase, p53, p21 and caspases 3, 8 and 9, and by a decrease in the levels of AKT and NF-κB. The cell population in the G1 phase decreased, and the S-phase population increased after AgNP treatment. AgNPs caused DNA damage and reduced the interaction between p53 and NF-κB. Interestingly, no significant alteration was noted in the levels of p21, BAX/BCL-XL and NF-κB after AgNP treatment in a p53-knockout HCT116 cell line.

CONCLUSION

AgNPs are bona fide anticancer agents that act in a p53-dependent manner. Original submitted 16 March 2012; Revised submitted 25 August 2012; Published online 21 March 2013.