Green synthesis of sodium alginate-silver nanoparticles and their antibacterial activity

A double-layer film based on the strategy of tannic acid-anthocyanin co-pigmentation and tannic-crosslinked-gelatin/-reduced Ag nanoparticles for beef preservation and monitoring

A double-layer film was developed with tannic acid (TA) co-pigmented purple potato anthocyanin extract (PAE)-agar as the inner layer, and K-carrageenan-oregano essential oil Pickering emulsion (OPE)/silver nanoparticles (TA-AgNPs) as the outer layer. Molecular docking and FT-IR results elucidated that intermolecular hydrogen bond was the main interaction between components in the agar-carrageenan matrix, with TA and PAE contributing to intensified anthocyanin color through π-π stacking. The incorporation of OPE/TA-AgNPs enhanced the film's hydrophobicity (WCA > 100°) and UV-vis barrier (close to 0% at 200-320 nm, effectively impeding UVA, UVB, and UVC) properties and exhibited outstanding antioxidant (DPPH scavenging rate > 88%) and antimicrobial activities. This film showed a significant color change in the pH range of 2-12 (from pink to yellow) and a considerable sensitivity to volatile amines within 2 min. The films effectively alleviated beef spoilage (extending the shelf life of beef for 1d) and reflected the freshness of beef during storage. Additionally, the digital color information of the film was obtained by a smartphone combined with RGB values analysis to quantify the freshness of beef rapidly. Therefore, this study expands the application of food packaging films with freshness preservation and monitoring in the field of animal-derived food.

Unleashing the power of polymeric nanoparticles - Creative triumph against antibiotic resistance: A review

Antibiotic resistance (ABR) poses a universal concern owing to the widespread use of antibiotics in various sectors. Nanotechnology emerges as a promising solution to combat ABR, offering targeted drug delivery, enhanced bioavailability, reduced toxicity, and stability. This comprehensive review explores concepts of antibiotic resistance, its mechanisms, and multifaceted approaches to combat ABR. The review provides an in-depth exploration of polymeric nanoparticles as advanced drug delivery systems, focusing on strategies for targeting microbial infections and contributing to the fight against ABR. Nanoparticles revolutionize antimicrobial approaches, emphasizing passive and active targeting. The role of various molecules, including small molecules, antimicrobial peptides, proteins, carbohydrates, and stimuli-responsive systems, is being explored in recent research works. The complex comprehension mechanisms of ABR and strategic use of nanotechnology present a promising avenue for advancing antimicrobial tactics, ensuring treatment efficacy, minimizing toxic effects, and mitigating development of ABR. Polymeric nanoparticles, derived from natural or synthetic polymers, are crucial in overcoming ABR. Natural polymers like chitosan and alginate exhibit inherent antibacterial properties, while synthetic polymers such as polylactic acid (PLA), polyethylene glycol (PEG), and polycaprolactone (PCL) can be engineered for specific antibacterial effects. This comprehensive study provides a valuable source of information for researchers, healthcare professionals, and policymakers engaged in the urgent quest to overcome ABR.

In-situ fabrication of resveratrol loaded sodium alginate coated silver nanoparticles for in vitro studies of mitochondrial-targeted anticancer treatment against MCF-7 cell lines

The study aims to improve the viability and stability of resveratrol by encapsulating metal-based biocompatible nanocarrier for mitochondrial-targeted delivery and breast cancer treatment. For this purpose, sodium alginate coated silver nanoparticles were synthesized by in-situ reduction of silver nitrate using sodium borohydride. The prepared nanoparticles and resveratrol-loaded nanoparticles were characterized by utilizing the following instruments including X-ray diffraction (XRD), UV visible spectroscopy, Photoluminescence (PL) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared (FTIR), Raman spectroscopy, Zeta potential. The dialysis method revealed increased resveratrol release in pH 5 phosphate buffer. The incorporation of resveratrol significantly stimulated the antioxidant activity of sodium alginate coated silver nanoparticles. MTT assay was employed to evaluate the biocompatibility and anticancer potential of developed sodium alginate coated silver nanoparticles and resveratrol-loaded nanoparticles with increasing concentrations against normal HaCaT and breast cancer MCF-7 cell lines respectively. Further, the apoptotic morphology of MCF-7 cells treated with sodium alginate coated nanoparticles and resveratrol loaded nanoparticles was evaluated by AO/EtBr staining and apoptosis was demonstrated in the form of green and red fluorescence. Mitochondrial staining with Mito-Tracker Red evaluated the targeted delivery of RES into mitochondria leading to apoptosis of cancer cells.

Rethinking Nanoparticle Synthesis: A Sustainable Approach vs. Traditional Methods

This review portrays a comparison between green protocols and conventional nanoparticle (NP) synthesis strategies, highlighting each method's advantages and limitations. Various top-down and bottom-up methods in NP synthesis are described in detail. The green chemistry principles are emphasized for designing safe processes for nanomaterial synthesis. Among the green biogenic sources plant extracts, vitamins, enzymes, polysaccharides, fungi (Molds and mushrooms), bacteria, yeast, algae, and lichens are discussed. Limitations in the reproducibility of green protocols in terms of availability of raw material, variation in synthetic protocol, and selection of material due to geographical differences are elaborated. Finally, a conclusion is drawn utilizing green chemical principles, & a circular economy strategy to minimize waste generation, offering a promising framework for the synthesis of NPs emphasizing sustainability.

Novel, Biosynthesis of Palladium Nanoparticles using Strychnos Potatorum Polysaccharide as a Green sustainable approach; and their effective Catalytic Hydrogenation of 4-Nitrophenol

In the current study, we successfully used strychnos potatorum polysaccharide through autoclaving to synthesize palladium nanoparticles in a green, sustainable process. These polysaccharide act as a stabilizing, capping, and reducing agent. It also used various analytical characterizations, including UV-Visible spectroscopy, FT-IR spectroscopy, X-Ray diffraction (XRD), Scanning electron microscopy (FE-SEM), EDAX, and X-ray photoelectron spectroscopy (XPS), TEM and gel permeation chromatography (GPC) are used to analyze biosynthesized pallidum nanoparticles (PdNPs). The surface plasmon resonance (SPR) band at 276 nm and UV-visible spectroscopy revealed the presence of the generated PdNPs. The XRD data show that PdNPs have crystalline behavior and a pristine face-centered cubic (FCC) structure. The PdNPs were successfully developed by catalytic reduction of 4-nitrophenol (4-NP). The catalytic activity and reusability of the environmentally friendly PdNPs catalyst were demonstrated by achieving a remarkable transformation of 95 % nitrophenol to 4-aminophenol after five cycles. The reaction rate constant (k) for the degradation of 4-nitrophenol (4-NP) using SP-PdNPs as a catalyst is 0.1201 min-1 and R2 0.9867, with a normalized rate constant of (Knor = K/m) of 7.206 s-1 mM-1. These findings provide fundamental knowledge of the catalytic process governing the hydrogenation of p-nitrophenol, which will help designers of effective catalysts. An innovative and affordable technique for creating PdNPs that are environmentally acceptable and can be utilized as effective catalysts in environmental applications is the use of strychnos potatorum gum polysaccharide. The green-synthesized PdNPs can be used for pollutant remediation, including pharmaceutical, domestic, heavy metal, industrial, and pesticide pollutants.

Alginate coated biogenic silver nanoparticles for the treatment of Pseudomonas infections in rainbow trout

Pseudomonas species are among the main pathogens causing rainbow trout infections. The present study provides a simple, green, sustainable, and rapid technique to synthesize of biogenic alginate-capped silver nanoparticles (Alg-Ag NPs) suitable for the treatment of Pseudomonas infections. It has been shown that the mechanism (aggregative or autocatalytic) of Alg-Ag NPs formation depended on Alg concentration and the heating approach used. The rate constants and activation energy were calculated. Alg-Ag NPs were characterized by UV-Vis, FTIR, XRD, TEM, AFM, XPS, and DLS. The optimal conditions for the fabrication of spherically-shaped (17-19 nm) and negatively-charged (zeta-potential <-50 mV) Alg-Ag NPs, which are stable during 9 months, included hot-plate assisted synthesis at 100 °C in diluted (1 mg/mL) Alg solutions. In vitro studies showed that Alg-Ag NPs exhibited prominent antimicrobial activity against collection Pseudomonas strains (inhibition zones ranged from 9.0 ± 1.0 to 19.0 ± 1.0 mm), with no significant loss of antibacterial efficacy after 9 months of storage. AFM analysis confirmed that the antibacterial effect of Alg-Ag NPs dealt with the direct nanomechanical disrupting of bacterial cells. The ability of Alg-Ag NPs to inhibit the growth of virulent P.aeruginosa, P.fluorescens and P. putida strains isolated from infected rainbow trout was evaluated. All tested strains were susceptible to Alg(10)-Ag NPs, while Alg(1)-Ag NPs demonstrated a limited strain-specific antibacterial effect. The obtained data displayed the prospects for the application of biogenic Alg-Ag NPs to create novel delivery systems for combating Pseudomonas infections in rainbow trout.

Marine Biomaterials: Hyaluronan

The marine-derived hyaluronic acid and other natural biopolymers offer exciting possibilities in the field of biomaterials, providing sustainable and biocompatible alternatives to synthetic materials. Their unique properties and abundance in marine sources make them valuable resources for various biomedical and industrial applications. Due to high biocompatible features and participation in biological processes related to tissue healing, hyaluronic acid has become widely used in tissue engineering applications, especially in the wound healing process. The present review enlightens marine hyaluronan biomaterial providing its sources, extraction process, structures, chemical modifications, biological properties, and biocidal applications, especially for wound healing/dressing purposes. Meanwhile, we point out the future development of wound healing/dressing based on hyaluronan and its composites and potential challenges.

The Development of Alginate/Ag NPs/Caffeic Acid Composite Membranes as Adsorbents for Water Purification

Since the water pollution problem still affects the environmental system and human health, the need to develop innovative membranes has become imperious. Lately, researchers have focused on developing novel materials to help diminish the contamination problem. The aim of present research was to obtain innovative adsorbent composite membranes based on a biodegradable polymer, alginate, to remove toxic pollutants. Of all pollutants, lead was chosen due to its high toxicity. The composite membranes were successfully obtained through a direct casting method. The silver nanoparticles (Ag NPs) and caffeic acid (CA) from the composite membranes were kept at low concentrations, which proved enough to bestow antimicrobial activity to the alginate membrane. The obtained composite membranes were characterised by Fourier transform infrared spectroscopy and microscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG-DSC). Swelling behaviour, lead ion (Pb²⁺) removal capacity, regeneration and reusability were also determined. Further, the antimicrobial activity was tested against selected pathogenic strains (S. aureus, E. faecalis sp., P. aeruginosa, E. coli and C. albicans). The presence of Ag NPs and CA improves the antimicrobial activity of the newly developed membranes. Overall, the composite membranes are suitable for complex water treatment (removal of heavy metal ions and antimicrobial treatment).

Direct-Writing Flexible Metal Circuit with Polymer/Metal Precursor Ink and Interfacial Reaction

In this study, flexible metal circuits are fabricated with polymer/metal precursor ink and an interfacial reaction by direct-writing technology. Poly(vinyl alcohol) (PVA) is selected as one component of ink, which could be a flexible composite in a metal circuit and an adhesive layer to connect the flexible metal circuit with the flexible substrate. Silver nitrate (AgNO₃) is added to the ink as a source of metal. After the direct-writing structure was placed in contact with an ascorbic acid (VC) aqueous solution with an adjustable process, silver nanoparticles (AgNPs) with 100-400 nm uniform size could be generated on the direct-writing PVA skeleton. The resistivity of the composite silver layer could reach 10^-6 Ω·m without any postprocessing. Meanwhile, the resistance change could keep within 20% with 180° bending after 10 000 repeat times. Patterned flexible metal circuits could be facilely fabricated by direct-writing technology, which presented excellent electrical conductivity and flexibility.

Dual-functional marine algal carbon-based materials with highly efficient dye removal and disinfection control

The design and simple, green preparation of dual-functional materials for the decontamination of both hazardous dyes and pathogenic microorganisms from wastewater remain challenging currently. Herein, a promising marine algal carbon-based material (named C-SA/SP) with both highly efficient dye adsorptive and antibacterial properties was fabricated based on the incorporation of sodium alginate and a low dose of silver phosphate via a facile and eco-friendly approach. The structure, removal of malachite green (MG) and congo red (CR), and their antibacterial performance were studied, and the adsorption mechanism was further interpreted by the statistical physics models, besides the classic models. The results show that the maximum simulated adsorption capacity for MG reached 2798.27 mg/g, and its minimal inhibit concentration for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 0.4 mg/mL and 0.2 mg/mL, respectively. The mechanistic study suggests that silver phosphate exerted the effects of catalytic carbon formation and pore formation, while reducing the electronegativity of the material as well, thus improving its dye adsorptive performance. Moreover, the MG adsorption onto C-SA/SP showed vertical orientation and a multi-molecular way, and its adsorption sites were involved in the adsorption process with the increase of temperature. Overall, the study indicates that the as-made dual-functional materials have good applied prospects for water remediation.

The green synthesis of environmentally friendly magnetic silver complex stabilized on MnCoFe2O4@sodium alginate nanoparticles (MCF@S-ALG/Ag) and evaluation of their antibacterial activity

Magnetic nanoparticles with green cover sodium alginate and Ag, MnCoFe₂O₄@Sodium alginate/Ag (MCF@S-ALG/Ag) MNPs were prepared by a simple and clean method from Sargassum Vulgare brown algae. The structure of these nanoparticles was characterized by the Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), field emission-scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Furthermore, the antibacterial activity of MCF@S-ALG/Ag MNPs was tested for two bacteria of gram-negative (Escherichia coli (E. coli)) bacteria and gram-positive (Staphylococcus aureus (S. aureus)) bacteria. The MCF@S-ALG/Ag MNPs showed the inhibition zone 16.32 mm for S. aureus and 12.84 mm for E. coli bacteria. The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of MCF@S-ALG/Ag MNPs for both bacteria were found 20 µg/mL and 40 µg/mL, respectively.

A biocompatible double-crosslinked gelatin/ sodium alginate/dopamine/quaterniazed chitosan hydrogel for wound dressings based on 3D bioprinting technology

438Severe skin injuries can cause serious problems, which could affect the patient's normal life, if not dealt properly in a timely and effective manner. It is an urgent requirement to develop personalized wound dressings with excellent antibacterial activity and biocompatibility to match the shape of the wound to facilitate clinical application. In this study, a bioink (GAQ) based on gelatin (Gel)/sodium alginate (SA)/ quaternized chitosan (QCS) was prepared, and GAQ hydrogel dressing grafting with dopamine (GADQ) was fabricated by an extrusion three-dimensional (3D) printing technology. QCS was synthesized by modifying quaternary ammonium group on chitosan, and its structure was successfully characterized by nuclear magnetic resonance (1H NMR) and Fourier-transform infrared spectroscopy (FT-IR). Our results showed that the GADQ hydrogel dressing that was double-crosslinked by EDC/ NHS and Ca²⁺ had good tensile strength, considerable swelling ratio, and effective antioxidation properties. It also showed that GADQ1.5% had 93.17% and 91.06% antibacterial activity against Staphylococcus aureus and Escherichia coli, respectively. Furthermore, the relative survival ratios of fibroblast cells seeded on these hydrogels exceeded 350% after cultured for 7 days, which proved the biocompatibility of these hydrogels. Overall, this advanced 3D-printed GADQ1.5% hydrogels with effective antioxidation, excellent antibacterial activity and good biocompatibility had a considerable application potential for wound healing.

Towards Greener and More Sustainable Synthesis of MXenes: A Review

The unique properties of MXenes have been deemed to be of significant interest in various emerging applications. However, MXenes provide a major drawback involving environmentally harmful and toxic substances for its general fabrication in large-scale production and employing a high-temperature solid-state reaction followed by selective etching. Meanwhile, how MXenes are synthesized is essential in directing their end uses. Therefore, making strategic approaches to synthesize greener, safer, more sustainable, and more environmentally friendly MXenes is imperative to commercialize at a competitive price. With increasing reports of green synthesis that promote advanced technologies and non-toxic agents, it is critical to compile, summarize, and synthesize the latest development of the green-related technology of MXenes. We review the recent progress of greener, safer, and more sustainable MXene synthesis with a focus on the fundamental synthetic process, the mechanism, and the general advantages, and the emphasis on the MXene properties inherited from such green synthesis techniques. The emerging use of the so-called green MXenes in energy conversion and storage, environmental remediation, and biomedical applications is presented. Finally, the remaining challenges and prospects of greener MXene synthesis are discussed.

Alginate Ag for Composite Hollow Fiber Membrane: Formation and Ethylene/Ethane Gas Mixture Separation

Membranes based on natural polymers, in particular alginate, are of great interest for various separation tasks. In particular, the possibility of introducing silver ions during the crosslinking of sodium alginate makes it possible to obtain a membrane with an active olefin transporter. In this work, the creation of a hollow fiber composite membrane with a selective layer of silver alginate is proposed for the first time. The approach to obtaining silver alginate is presented in detail, and its sorption and transport properties are also studied. It is worth noting the increased selectivity of the material for the ethylene/ethane mixture (more than 100). A technique for obtaining a hollow fiber membrane from silver alginate has been developed, and its separating characteristics have been determined. It is shown that in thin layers, silver alginate retains high values of selectivity for the ethylene/ethane gas pair. The obtained gas transport properties demonstrate the high potential of using membranes based on silver alginate for the separation of an olefin/paraffin mixture.

Strategies adopted for the preparation of sodium alginate–based nanocomposites and their role as catalytic, antibacterial, and antifungal agents

Alginate extracted from the marine brown algae is a massively utilized biopolymer in multiple fields such as microreactors for the fabrication of metal nanoparticles along with other polymeric and nonpolymeric materials to enhance their mechanical strength. These sodium alginate (Na-Alg)-based fabricated nanocomposites find applications in the field of catalysis and biological treatment as antibacterial/antifungal agent due to the synergistic properties of Na-Alg and fabricated metal nanoparticles (NPs). Na-Alg offers mechanical strength and nanoparticles provide high reactivity due to their small size. Sodium alginate exhibits hydroxyl and carboxylate functional groups that can easily interact with the metal nanoparticles to form composite particles. The research on the preparation of Na-Alg–based nanoparticles and nanoaggregates have been started recently but developed quickly due to their extensive applications in different fields. This review article encircles different methods of preparation of sodium alginate–based metal nanocomposites; analytical techniques reported to monitor the formation of these nanocomposites and used to characterize these nanocomposites as well as applications of these nanocomposites as catalyst, antibacterial, and antifungal agent.

Bioactive Edible Sodium Alginate Films Incorporated with Tannic Acid as Antimicrobial and Antioxidative Food Packaging

Currently, biodegradable and functional food packaging materials have attracted more and more attention due to their potential advantages. Biopolymers are one of the promising materials used to produce biodegradable food packaging films, and sodium alginate (SA) is one of the most used polysaccharides. In this work, we explored a novel edible sodium alginate (SA)/tannic acid (TA) film as biodegradable active food packaging material. The impact of TA concentration on the UV light blocking ability, transparency, water vapor barrier ability, mechanical strength, antioxidant, and antimicrobial activity of the SA-TA films was comprehensively investigated. Fourier transform infrared spectroscopy results revealed that strong hydrogen bonding was the main intermolecular interaction between SA and TA. As TA concentration in the films increased, the water vapor permeability (WVP) decreased from 1.24 × 10^-6 to 0.54 × 10^-6 g/m/h/Pa, the DPPH radical scavenging activity increased from 0.008% to 89.02%. Moreover, the incorporation of TA effectively blocked UV light and elevated antimicrobial activity against Escherichia coli. Overall, the SA films with TA exhibited better water vapor barrier ability, remarkable UV-light barrier ability and antioxidant activity while showing a slight decrease in light transmittance. These results indicated the potential application of TA as a functional additive agent for developing multifunctional food packaging materials.

Inhalation of Silver Silicate Nanoparticles Leads to Transient and Differential Microglial Activation in the Rodent Olfactory Bulb

Engineered silver nanoparticles (AgNPs), including silver silicate nanoparticles (Ag-SiO₂ NPs), are used in a wide variety of medical and consumer applications. Inhaled AgNPs have been found to translocate to the olfactory bulb (OB) after inhalation and intranasal instillation. However, the biological effects of Ag-SiO₂ NPs and their potential nose-to-brain transport have not been evaluated. The present study assessed whether inhaled Ag-SiO₂ NPs can elicit microglial activation in the OB. Adult Sprague-Dawley rats inhaled aerosolized Ag-SiO₂ NPs at a concentration of 1 mg/ml for 6 hours. On day 0, 1, 7, and 21 post-exposure, rats were necropsied and OB were harvested. Immunohistochemistry on OB tissues were performed with anti-ionized calcium-binding adapter molecule 1 and heme oxygenase-1 as markers of microglial activation and oxidative stress, respectively. Aerosol characterization indicated Ag-SiO₂ NPs were sufficiently aerosolized with moderate agglomeration and high-efficiency deposition in the nasal cavity and olfactory epithelium. Findings suggested that acute inhalation of Ag-SiO₂ NPs elicited transient and differential microglial activation in the OB without significant microglial recruitment or oxidative stress. The delayed and differential pattern of microglial activation in the OB implied that inhaled Ag-SiO₂ may have translocated to the central nervous system via intra-neuronal pathways.

Nanomaterials-Based Combinatorial Therapy as a Strategy to Combat Antibiotic Resistance

Since the discovery of antibiotics, humanity has been able to cope with the battle against bacterial infections. However, the inappropriate use of antibiotics, the lack of innovation in therapeutic agents, and other factors have allowed the emergence of new bacterial strains resistant to multiple antibiotic treatments, causing a crisis in the health sector. Furthermore, the World Health Organization has listed a series of pathogens (ESKAPE group) that have acquired new and varied resistance to different antibiotics families. Therefore, the scientific community has prioritized designing and developing novel treatments to combat these ESKAPE pathogens and other emergent multidrug-resistant bacteria. One of the solutions is the use of combinatorial therapies. Combinatorial therapies seek to enhance the effects of individual treatments at lower doses, bringing the advantage of being, in most cases, much less harmful to patients. Among the new developments in combinatorial therapies, nanomaterials have gained significant interest. Some of the most promising nanotherapeutics include polymers, inorganic nanoparticles, and antimicrobial peptides due to their bactericidal and nanocarrier properties. Therefore, this review focuses on discussing the state-of-the-art of the most significant advances and concludes with a perspective on the future developments of nanotherapeutic combinatorial treatments that target bacterial infections.

An Overview of Green Synthesis and Potential Pharmaceutical Applications of Nanoparticles as Targeted Drug Delivery System in Biomedicines

Nanotechnology-based nanomedicine offers several benefits over conventional forms of therapeutic agents. Moreover, nanomedicine has become a potential candidate for targeting therapeutic agents at specific sites. However, nanomedicine prepared by synthetic methods may produce unwanted toxic effects. Due to their nanosize range, nanoparticles can easily reach the reticuloendothelial system and may produce unwanted systemic effects. The nanoparticles produced by the green chemistry approach would enhance the safety profile by avoiding synthetic agents and solvents in its preparations. This review encompasses toxicity consideration of nanoparticles, green synthesis techniques of nanoparticle preparation, biomedical application of nanoparticles, and future prospects.

Shaping and Patterning Supramolecular Materials─Stem Cell-Compatible Dual-Network Hybrid Gels Loaded with Silver Nanoparticles

Hydrogels with spatio-temporally controlled properties are appealing materials for biological and pharmaceutical applications. We make use of mild acidification protocols to fabricate hybrid gels using calcium alginate in the presence of a preformed thermally triggered gel based on a low-molecular-weight gelator (LMWG) 1,3:2:4-di(4-acylhydrazide)-benzylidene sorbitol (DBS-CONHNH₂). Nonwater-soluble calcium carbonate slowly releases calcium ions over time when exposed to an acidic pH, triggering the assembly of the calcium alginate gel network. We combined the gelators in different ways: (i) the LMWG was used as a template to spatially control slow calcium alginate gelation within preformed gel beads, using glucono-δ-lactone (GdL) to lower the pH; (ii) the LMWG was used as a template to spatially control slow calcium alginate gelation within preformed gel trays, using diphenyliodonium nitrate (DPIN) as a photoacid to lower the pH, and spatial resolution was achieved by masking. The dual-network hybrid gels display highly tunable properties, and the beads are compatible with stem cell growth. Furthermore, they preserve the LMWG function of inducing in situ silver nanoparticle (AgNP) formation, which provides the gels with antibacterial activity. These gels have potential for eventual regenerative medicine applications in (e.g.) bone tissue engineering.

Characterization and Toxicity of Hypoxoside Capped Silver Nanoparticles

The reducing potential of plant extracts in the green synthesis of nanoparticles has been associated with their phytochemicals. Although pharmacologically inactive, a norlignan diglucoside “hypoxoside” (HP) occurs in large quantities in the extract of Hypoxis hemerocallidea (HE). In this work, HP was isolated from HE where both were used in the biosynthesis of the corresponding silver nanoparticles (HP-AgNPs and HE-AgNPs). The AgNPs were fully characterized using various physicochemical techniques and their antimicrobial and anticancer properties were evaluated. Transmission electron microscopy (TEM) revealed sizes of 24.3 ± 4 nm for the HE-AgNPs and 3.9 ± 1.6 nm for the HP-AgNPs. The HE-AgNPs demonstrated enhanced anti-bactericidal effects on Escherichia coli and Salmonella enterica with a minimum inhibitory concentration (MIC) value of 1.95 µg/mL, competing well with the standard drug. The cytotoxic activity showed that the HE-AgNPs reduced cell viability with an IC50 of 0.81 and 4.0 µg/mL, respectively, for the U87 and U251 cells, while the HP-AgNPs displayed 0.20 and 0.55 µg/mL for both cell lines, respectively. Furthermore, while the HE-AgNPs were selective to U87 alone, the HP-AgNPs were selective to both glioblastoma cells tested. The study demonstrated the ability of a single phytoconstituent (hypoxoside), not only as the chief bioreductant in the extract, but also as a standalone reducing and capping agent, producing ultra-small, spherical, and monodispersed AgNPs with enhanced biological properties.

Preparation of chitosan/sodium alginate/nano cellulose composite for the efficient removal of cadmium (II) cations from wastewater and soil systems

In this study, chitosan/sodium alginate/nano cellulose (CSA-N) nanocomposite hydrogels were prepared using a completely green route and used as sorbents to adsorb Cd²⁺ ions from water and soil systems of an environmental aspect. The sorbents were characterized by FTIR, SEM, and XRD. The influences of initial Cd²⁺ concentration, the presence of nano cellulose, type of the polluted environment, and ionic strength on adsorption and desorption isotherms were investigated. The maximum adsorption capacity of cadmium onto CSA was significantly increased from 2264.9 to 4380.97 μmol/g when the system was changed from soil to water, respectively. While, the maximum adsorption capacity of cadmium onto CSA-N was almost the same in the soil and wastewater systems, i.e., 3419.5 and 3230.3 µmol/g, respectively. The results indicated that Langmuir and Freundlich models provided the best fit for the experimental adsorption data for CSA and CSA-N, respectively. By comparing the amounts of Δq, the difference between adsorption and desorption amounts, the CSA was not economically feasible sorbent at high initial concentrations of Cd²⁺ in the wastewater system, while, CSA-N was demonstrated to be a more efficient adsorbent than CSA for cadmium removal from both the soil and wastewater systems.

Alginate poly and oligosaccharide (AOS) from Sargassum sp. as immunostimulant in gnotobiotic artemia challenge tests and antibacterial diffusion disc assay against pathogenic Vibrio parahaemolyticus, V. vulnificus and V. harveyi

Alginate is a polysaccharide derived from Sargassum sp. and is a potent immunostimulant with antibacterial activity, including against Vibrio spp. This genus of bacteria is found in freshwater and marine environments and is a common infectious, pathogenic bacteria both for aquatic cultivans and humans. Here, we determined the ability of sodium alginate polysaccharides and oligosaccharides (AOS) to act as immunostimulants in Artemia challenge tests and antibacterial diffusion disc assays against Vibrio parahaemolyticus, V. vulnificus, and V. harveyi. The AOS was produced by thermal heating. Dry sodium alginates were weighed out from 4.21 to 6.47 grams with a yield varying from 21.05 to 32.35%. Alginate polysaccharides were challenged against V harveyi and showed 8 positive results. The highest inhibitor zone was 12.962±3.623 mm. Based on 18 tests, AOS showed 12 positive results, with the highest inhibitor zone being 10.250±0.09 mm. The encapsulated alginate against Vibrio parahaemolyticus, Vibrio harveyi, Vibrio vulnificus, and the non-challenged tests without any Vibrio spp. addition resulted in the best concentrations of 800 ppm (polysaccharide) and 600 ppm (oligosaccharide), respectively. The lower concentration of oligosaccharides alginate were more effective and has the potential to be superior as an antibacterial agent and immunestimulant, as opposed to alginate polysaccharide.

Green synthesis of silver nanoparticles using sodium alginate and tannic acid: characterization and anti-S. aureus activity

Multi-drug resistance and biofilm formation are a growing problem in the treatment of Staphylococcus aureus contamination. Advances in nanotechnology allow the synthesis of metal nanoparticles that can be assembled into complex architectures for controlling bacterial growth. This study aims to investigate the ultrasonic-assisted green synthesis of silver nanoparticles (AgNPs) by tannic acid (TA) and sodium alginate (Na-Alg) as the reducing and stabilizing agents, respectively, and evaluation of their antibacterial and antibiofilm activities. The UV-Vis spectroscopy and transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), zetasizer, FT-IR spectroscopy, and X-ray diffraction (XRD) studies showed that the optimum produces were spherical, stable, and monodispersed AgNPs with an average size of particle sizes of 18.52 ± 0.07 nm. The antibacterial and antibiofilm activities of the AgNPs loaded TA/Na-Alg constructs against S. aureus ATCC 6538 were investigated. The minimum inhibitory concentration (MIC) of the AgNPs was 31.25 μg/mL. After exposure to the AgNPs, planktonic S. aureus showed irreversible cell membrane damage, decreased cell viability, and changes in cellular morphology. In addition, the AgNps significantly inhibited S. aureus biofilm formation at 1/32 MIC. The biofilm elimination rate was 58.87% after exposure to MIC AgNPs. The results suggested that the development of AgNPs loaded TA/Na-Alg constructs with biomedical potentialities obtained through a simple, green, and cost-effective approach, may be suitable for the formulation of a new strategy for combating S. aureus.

Green synthesis of silver nanoparticles and evaluation of their anti-bacterial activities: use of Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts

The presence of various phytochemicals makes the leaf extract-based green synthesis advantageous to other conventional methods, as it facilitates the production of non-toxic by-product. In the present study, leaf extracts from two different plants: Aloe barbadensis miller and Ocimum tenuiflorum, were used to synthesise Ag nanoparticles. The absorbance at 419-432 nm from UV-visible spectroscopy indicates the formation of Ag in the synthesised samples. The effect of precursors’ concentration on the stability, size and shape of the synthesised samples has also been investigated at constant heating temperature, stirring time, and the pH of the solution. The TEM results showed that all the synthesised samples of nanoparticles demonstrated stability with a size range of 7-70 and 9-48 nm with Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts, respectively. The formation of smaller Ag nanoparticles due to utilisation of different precursor concentration and leaf extracts was also explained. The synthesised samples’ anti-bacterial activity was examined against the pathogens, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. In general, the green synthesis approach established a prospective for developing highly stable Ag nanoparticles with rigid particle shape/size distribution from different leaf extracts for the development of better anti-bacterial agents.

Alginate-Capped Silver Nanoparticles as a Potent Anti-mycobacterial Agent Against Mycobacterium tuberculosis

Tuberculosis (TB) is a leading cause of death from a single infectious agent, Mycobacterium tuberculosis (Mtb). Although progress has been made in TB control, still about 10 million people worldwide develop TB annually and 1.5 million die of the disease. The rapid emergence of aggressive, drug-resistant strains and latent infections have caused TB to remain a global health challenge. TB treatments are lengthy and their side effects lead to poor patient compliance, which in turn has contributed to the drug resistance and exacerbated the TB epidemic. The relatively low output of newly approved antibiotics has spurred research interest toward alternative antibacterial molecules such as silver nanoparticles (AgNPs). In the present study, we use the natural biopolymer alginate to serve as a stabilizer and/or reductant to green synthesize AgNPs, which improves their biocompatibility and avoids the use of toxic chemicals. The average size of the alginate-capped AgNPs (ALG-AgNPs) was characterized as nanoscale, and the particles were round in shape. Drug susceptibility tests showed that these ALG-AgNPs are effective against both drug-resistant Mtb strains and dormant Mtb. A bacterial cell-wall permeability assay showed that the anti-mycobacterial action of ALG-AgNPs is mediated through an increase in cell-wall permeability. Notably, the anti-mycobacterial potential of ALG-AgNPs was effective in both zebrafish and mouse TB animal models in vivo. These results suggest that ALG-AgNPs could provide a new therapeutic option to overcome the difficulties of current TB treatments.

Hybrid levan-Ag/AgCl nanoparticles produced by UV-irradiation: properties, antibacterial efficiency and application in bioactive poly(vinyl alcohol) films

Foodborne diseases caused by resistance of microorganisms to multiple antimicrobial agents have emerged as a major public health concern around the world. The search for potential antimicrobials has resulted in the emergence of metal nanoparticles for protection against these infections. In this study an eco-friendly and green approach was used to biosynthesize hybrid Ag/AgCl nanoparticles (NPs), using levan from Bacillus mojavensis as a stabilizing/reducing agent, with a high efficiency against a broad spectrum of foodborne bacteria as well as biofilm formations. The morphology and physicochemical characteristics of levan-Ag/AgCl NPs were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis spectroscopy (UV), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The hybrid levan-Ag/AgCl was evaluated for antibacterial activity against foodborne pathogenic bacteria (Escherichia coli, Klebsiella pneumoniae, Salmonella enterica, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes, Enterococcus faecalis, Bacillus subtilis and Bacillus thuringiensis). The study demonstrated the strong efficiency of hybrid levan-Ag/AgCl NPs as a potent inhibitor against all tested strains, with much higher activity against Gram-negative than Gram-positive bacteria. Furthermore, bacterial strains were found to be highly sensitive to hybrid levan-Ag/AgCl NPs in comparison to the tested antibiotics. As a possible application of levan-Ag/AgCl NPs as an additive in packaging, PVA films with different amounts of hybrid levan-Ag/AgCl NPs were prepared by casting and their antibacterial, mechanical, and optical properties and ability to expand the shelf life of beef meat were explored. Interestingly, the amount of Ag leached out from films was below the permissible limit. This work demonstrates the strong antibacterial action of hybrid levan-Ag/AgCl NPs and their potential use in bioactive packaging material.

Silver-Protein Nanocomposites as Antimicrobial Agents

The use of nanomaterials alone or in composites with proteins is a promising alternative to inhibit pathogenic bacteria. In this regard, this study used seed proteins from both fenugreek (Trigonella foenum-graecum L.) (FNP) and mung bean (Viga radiate) (MNP), with silver nanoparticles (Ag-NPs) and nanocomposites of either Ag-NPs plus FNP (Ag-FNP) or Ag-NPs plus MNP (Ag-MNP) as inhibitory agents against pathogenic bacteria. FNP and MNP were isolated from fenugreek seeds and mung bean seeds, respectively, and fractionated using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Both FNP and MNP were immobilized with Ag-NPs to synthesize the nanocomposites Ag-FNP and Ag-MNP, respectively. The physicochemical characteristics of Ag-NPs and their composites with proteins were studied by X-ray Diffraction (XRD), dynamic light scattering (DLS), the zeta potential, Scanning and Transmission Electron Microscopy (SEM and TEM, respectively), Atomic Force Microscopy (AFM), and the Brunauer-Emmett-Teller isotherm (BET), elucidating their structural parameters, size distribution, size charges, size surface morphology, particle shape, dimensional forms of particles, and specific surface area, respectively. The sole proteins, Ag-NPs, and their nanocomposites inhibited pathogenic Gram-positive and Gram-negative bacteria. The inhibitory activities of both nanocomposites (Ag-FNP and Ag-MNP) were more than those obtained by either Ag-NPs or proteins (FNP, MNP). Minimum inhibitory concentrations (MICs) of Ag-FNP were very low (20 and 10 µg mL-1) against Salmonellatyphimurium and Pseudomonasaerugenosa, respectively, but higher (162 µg mL-1) against E. coli and Listeriamonocytogenes. MICs of Ag-MNP were also very low (20 µg mL-1) against Staphylococcusaureus but higher (325 µg mL-1) against Listeriamonocytogenes. TEM images of Staphylococcusaureus and Salmonellatyphimurium, treated with Ag-FNP and Ag-MNP, at their MIC values, showed asymmetric, wrinkled exterior surfaces, cell deformations, cell depressions, and diminished cell numbers.

Bionanofactories for Green Synthesis of Silver Nanoparticles: Toward Antimicrobial Applications

Among the various types of nanoparticles and their strategy for synthesis, the green synthesis of silver nanoparticles has gained much attention in the biomedical, cellular imaging, cosmetics, drug delivery, food, and agrochemical industries due to their unique physicochemical and biological properties. The green synthesis strategies incorporate the use of plant extracts, living organisms, or biomolecules as bioreducing and biocapping agents, also known as bionanofactories for the synthesis of nanoparticles. The use of green chemistry is ecofriendly, biocompatible, nontoxic, and cost-effective. We shed light on the recent advances in green synthesis and physicochemical properties of green silver nanoparticles by considering the outcomes from recent studies applying SEM, TEM, AFM, UV/Vis spectrophotometry, FTIR, and XRD techniques. Furthermore, we cover the antibacterial, antifungal, and antiparasitic activities of silver nanoparticles.

Green Synthesized Silver Nanoparticles Immobilized on Activated Carbon Nanoparticles: Antibacterial Activity Enhancement Study and Its Application on Textiles Fabrics

This research aimed to enhance the antibacterial activity of silver nanoparticles (AgNPs) synthesized from silver nitrate (AgNO3) using aloe vera extract. It was performed by means of incorporating AgNPs on an activated carbon nanoparticle (ACNPs) under ultrasonic agitation (40 kHz, 2 × 50 watt) for 30 min in an aqueous colloidal medium. The successful AgNPs synthesis was clarified with both Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) spectrophotometers. The successful AgNPs-ACNPs incorporation and its particle size analysis was performed using Transmission Electron Microscope (TEM). The brown color suspension generation and UV-Vis's spectra maximum wavelength at around 480 nm confirmed the existence of AgNPs. The particle sizes of the produced AgNPs were about 5 to 10 nm in the majority number, which collectively surrounded the aloe vera extract secondary metabolites formed core-shell like nanostructure of 8.20 ± 2.05 nm in average size, while ACNPs themselves were about 20.10 ± 1.52 nm in average size formed particles cluster, and 48.00 ± 8.37 nm in average size as stacking of other particles. The antibacterial activity of the synthesized AgNPs and AgNPs-immobilized ACNPs was 57.58% and 63.64%, respectively (for E. coli); 61.25%, and 93.49%, respectively (for S. aureus). In addition, when the AgNPs-immobilized ACNPs material was coated on the cotton and polyester fabrics, the antibacterial activity of the materials changed, becoming 19.23% (cotton; E. coli), 31.73% (polyester; E. coli), 13.36% (cotton; S. aureus), 21.15% (polyester; S. aureus).

Lichens-A Potential Source for Nanoparticles Fabrication: A Review on Nanoparticles Biosynthesis and Their Prospective Applications

Green synthesis of nanoparticles (NPs) is a safe, eco-friendly, and relatively inexpensive alternative to conventional routes of NPs production. These methods require natural resources such as cyanobacteria, algae, plants, fungi, lichens, and naturally extracted biomolecules such as pigments, vitamins, polysaccharides, proteins, and enzymes to reduce bulk materials (the target metal salts) into a nanoscale product. Synthesis of nanomaterials (NMs) using lichen extracts is a promising eco-friendly, simple, low-cost biological synthesis process. Lichens are groups of organisms including multiple types of fungi and algae that live in symbiosis. Until now, the fabrication of NPs using lichens has remained largely unexplored, although the role of lichens as natural factories for synthesizing NPs has been reported. Lichens have a potential reducible activity to fabricate different types of NMs, including metal and metal oxide NPs and bimetallic alloys and nanocomposites. These NPs exhibit promising catalytic and antidiabetic, antioxidant, and antimicrobial activities. To the best of our knowledge, this review provides, for the first time, an overview of the main published studies concerning the use of lichen for nanofabrication and the applications of these NMs in different sectors. Moreover, the possible mechanisms of biosynthesis are discussed, together with the various optimization factors influencing the biological synthesis and toxicity of NPs.

Synthesis of gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite based on chemical oxidative polymerization for biological applications

Gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite ((PABA-SAL)@AuNPs) was fabricated. Aniline boronic acid (ABA) served as reductant of gold salt, all within the SAL solution. While ABA reduced gold salt to its nanoparticles, the ABA monomer was also oxidized to its conducting polymeric form (PABA). The presence of PABA in the reaction mixture exerted solubility and stability challenge, thus SAL was used as stabilizer and solubilizer for PABA. The numerous cis-diol groups of SAL could bind to boronic acid groups of PABA to furnish PABA-SAL repeating polymer structure for AuNPs anchoring. Sparkling ruby red (PABA-SAL)@AuNPs have absorption peaks at 529 and 718 nm. Average particle sizes of nanocomposite were within 15-20 nm, with hydrodynamic diameter of 48.6 ± 0.9 nm, zeta potential of -32.5 ± 1.6 mV and conductivity value of 2015.3 ± 3.2 μS/cm. (PABA-SAL)@AuNPs possessed antibacterial activities against seafood associated bacterial isolates, with MIC and MBC ranging from 4 to 8 μg/mL. The moderate antioxidant capacity of (PABA-SAL)@AuNPs was observed, without any deleterious damages on human red blood cells. It also has good biocompatibility on Caco-2 and RAW 264.7, with cell viability not less than 70%. These results confirm the high prospect of (PABA-SAL)@AuNPs for possible biomedical applications.

Sensitive colorimetric detection of ascorbic acid based on seed mediated growth of sodium alginate reduced/stabilized gold nanoparticles

A sensitive detection strategy for ascorbic acid (AA), using sodium alginate reduced/stabilized gold nanoparticles (SA-AuNPs) as the optical probe, is reported. The SA-AuNPs were prepared by mixing gold salt and SA under stirring for 2 h at room temperature, without any further steps. The mixture was aged at 4 °C overnight, after which a faint-purple colloidal solution of SA-AuNPs was obtained. Characterization shows that the synthesis is incapable of reducing all Au³⁺ to Au°, but rather to mixture of Au°/Au⁺. The addition of AA to the SA-AuNPs probe reduced completely all Au⁺ to new AuNPs which were deposited on the pre-formed SA-AuNPs seed, leading to size increment and absorption spectra enhancement. The assay exhibited a good linearity between 12.5 and 150.0 μM AA and low limit of quantification of 11.2 μM. It was further used for AA quantitation in vitamin C injection and fruit juice with satisfactory accuracy and precision.

Distinctive detection of Fe2+ and Fe3+ by biosurfactant capped silver nanoparticles via naked eye colorimetric sensing

Distinctive detection of Fe²⁺ and Fe³⁺via naked eye colorimetic sensing.

Characterization of alginate-capped nanosilver by fractal and entropy analysis on its transmission electron microphotographs

The study employs conventional techniques and quantitative image analysis tools to characterize alginate-capped nanosilver synthesized by green methods. Sodium Alginate (0.5 %, 1 % and 2 %) was used as a reducing and stabilizing agent. Presence of particles was confirmed by UV-vis Spectroscopy, with absorbance maxima of 412-413 nm for 0.5 %, 1 % and 2 % of polymer. Hydrodynamic sizes of particles recorded for 0.5 %, 1 % and 2 % polymer were 128.4 ± 1.5, 129.9 ± 3.6 and 148.6 ± 1.0 nm by DLS. TEM revealed roughly spherical to cuboidal particles ranging from 15-20 nm and clusters of 100 nm and Energy Dispersive X-ray Spectroscopy confirmed the presence of silver in the particles. Analysis of the TEM images was done in MATLAB R2016b using histogram equalisation for image enhancement and entropy filtering for image segmentation. These techniques revealed the surface pores and polymer distribution around the particle. Statistical analysis (ANOVA) was performed for the measured fractal dimensions of nanoparticles with polymer coating, width of particle together with polymer coating, and thickness of only polymer coating around the particle for various study groups. Significant differences (p < 0.05) were found both between and within the study groups for fractal dimensions of nanoparticles with polymer coating, width of nanoparticles and thickness of polymer coating alone. The analysis was successful in confirming presence and thickness of polymer layer on particles.

Green Synthesis of Gold and Silver Nanoparticles by Using Amorphophallus paeoniifolius Tuber Extract and Evaluation of Their Antibacterial Activity

In this report, we discussed rapid, facile one-pot green synthesis of gold and silver nanoparticles (AuNPs and AgNPs) by using tuber extract of Amorphophallus paeoniifolius, and evaluated their antibacterial activity. AuNPs and AgNPs were synthesized by mixing their respective precursors (AgNO₃ and HAuCl₄) with tuber extract of Amorphophallus paeoniifolius as the bio-reducing agent. Characterization of AuNPs and AgNPs were confirmed by applying UV-vis spectroscopy, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDS). From UV-vis characterization, surface plasmon resonance spectra were found at 530 nm for AuNPs and 446 nm for AgNPs. XRD data confirmed that both synthesized nanoparticles were face-centered cubic in crystalline nature, and the average crystallite sizes for the assign peaks were 13.3 nm for AuNPs and 22.48 nm for AgNPs. FTIR data evaluated the characteristic peaks of different phytochemical components of tuber extract, which acted as the reducing agent, and possibly as stabilizing agents. The antibacterial activity of synthesized AuNPs and AgNPs were examined in Muller Hinton agar, against two Gram-positive and four Gram-negative bacteria through the disc diffusion method. AuNPs did not show any inhibitory effect, while AgNPs showed good inhibitory effect against both Gram-positive and Gram-negative bacteria.

Biosynthesis, Characterization, and Biological Activities of Procyanidin Capped Silver Nanoparticles

In this study, procyanidin dimers and Leucosidea sericea total extract (LSTE) were employed in the synthesis of silver nanoparticles (AgNPs) and characterized by ultraviolet-visible (UV-Visible) spectroscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. AgNPs of about 2–7 nm were obtained. DLS and stability evaluations confirmed that the AgNPs/procyanidins conjugates were stable. The formed nanoparticles exhibited good inhibitory activities against the two enzymes studied. The IC₅₀ values against the amylase enzyme were 14.92 ± 1.0, 13.24 ± 0.2, and 19.13 ± 0.8 µg/mL for AgNPs coordinated with LSTE, F1, and F2, respectively. The corresponding values for the glucosidase enzyme were 21.48 ± 0.9, 18.76 ± 1.0, and 8.75 ± 0.7 µg/mL. The antioxidant activities were comparable to those of the intact fractions. The AgNPs also demonstrated bacterial inhibitory activities against six bacterial species. While the minimum inhibitory concentrations (MIC) of F1-AgNPs against Pseudomonas aeruginosa and Staphylococcus aureus were 31.25 and 15.63 µg/mL respectively, those of LSTE-AgNPs and F2-AgNPs against these organisms were both 62.50 µg/mL. The F1-AgNPs demonstrated a better bactericidal effect and may be useful in food packaging. This research also showed the involvement of the procyanidins as reducing and capping agents in the formation of stable AgNPs with potential biological applications.

Nanotechnology application in food packaging: A plethora of opportunities versus pending risks assessment and public concerns

Environmental factors, oxidation and microorganisms contamination, are the major causes for food spoilage, which leads to sensory features alteration, loss of quality, production of harmful chemicals and growth of foodborne pathogens capable to cause severe illness. Synthetic preservatives, traditional conserving methods and food packaging (FP), although effective in counteracting food spoilage, do not allow the real-time monitoring of food quality during storage and transportation and assent a relatively short shelf life. In addition, FP may protect food by the spoilage caused by external contaminations, but is ineffective against foodborne microorganisms. FP preservative functionalities could be improved adding edible natural antioxidants and antimicrobials, but such chemicals are easily degradable. Nowadays, thanks to nanotechnology techniques, it is possible to improve the FP performances, formulating and inserting more stable antioxidant/antimicrobial ingredients, improving mechanical properties and introducing intelligent functions. The state-of-the-art in the field of nanomaterial-based improved FP, the advantages that might derive from their extensive introduction on the market and the main concerns associated to the possible migration and toxicity of nanomaterials, frequently neglected in existing reviews, have been herein discussed.