Metal-Based Nanoparticles in Food Packaging and Coating Technologies: A Review.

Food security has continued to be a topic of interest in our world due to the increasing demand for food. Many technologies have been adopted to enhance food supply and narrow the demand gap. Thus, the attempt to use nanotechnology to improve food security and increase supply has emerged due to the severe shortcomings of conventional technologies, which have made them insufficient to cater to the continuous demand for food products. Hence, nanoparticles have been identified to play a major role in areas involving food production, protection, and shelf-life extensions. Specifically, metal-based nanoparticles have been singled out to play an important role in manufacturing materials with outstanding properties, which can help increase the shelf-life of different food materials. The physicochemical and biological properties of metal-based nanoparticles, such as the large surface area and antimicrobial properties, have made them suitable and adequately useful, not just as a regular packaging material but as a functional material upon incorporation into biopolymer matrices. These, amongst many other reasons, have led to their wide synthesis and applications, even though their methods of preparation and risk evaluation remain a topic of concern. This review, therefore, briefly explores the available synthetic methods, physicochemical properties, roles, and biological properties of metal-based nanoparticles for food packaging. Furthermore, the associated limitations, alongside quality and safety considerations, of these materials were summarily explored. Although this area of research continues to garner attention, this review showed that metal-based nanoparticles possess great potential to be a leading material for food packaging if the problem of migration and toxicity can be effectively modulated.

Biogenic Synthesis of CuO, ZnO, and CuO-ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties.

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO-ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO-ZnO composite. The electron microscopy of the CuO-ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent's analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO-ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC50) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO-ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.

Plant Extracts Mediated Metal-Based Nanoparticles: Synthesis and Biological Applications.

The vastness of metal-based nanoparticles has continued to arouse much research interest, which has led to the extensive search and discovery of new materials with varying compositions, synthetic methods, and applications. Depending on applications, many synthetic methods have been used to prepare these materials, which have found applications in different areas, including biology. However, the prominent nature of the associated toxicity and environmental concerns involved in most of these conventional methods have limited their continuous usage due to the desire for more clean, reliable, eco-friendly, and biologically appropriate approaches. Plant-mediated synthetic approaches for metal nanoparticles have emerged to circumvent the often-associated disadvantages with the conventional synthetic routes, using bioresources that act as a scaffold by effectively reducing and stabilizing these materials, whilst making them biocompatible for biological cells. This capacity by plants to intrinsically utilize their organic processes to reorganize inorganic metal ions into nanoparticles has thus led to extensive studies into this area of biochemical synthesis and analysis. In this review, we examined the use of several plant extracts as a mediating agent for the synthesis of different metal-based nanoparticles (MNPs). Furthermore, the associated biological properties, which have been suggested to emanate from the influence of the diverse metabolites found in these plants, were also reviewed.

Synthesis, Theoretical Calculation, and Biological Studies of Mono- and Diphenyltin(IV) Complexes of N-Methyl-N-hydroxyethyldithiocarbamate.

In this study, chlorophenyltin(IV) [(C6H5)(Cl)Sn(L)2] and diphenyltin(IV) [(C6H5)2Sn(L)2] of N-methyl-N-hydroxyethyldithiocarbamate were prepared and characterized using various spectroscopic methods (FTIR, 1H, 13C, and 119Sn NMR) and elemental analysis. The FTIR and NMR spectral data, used to establish the structure of the compounds, showed the formation of the complexes via coordination to the two sulfur atoms from the dithiocarbamate ligand and the respective phenyltin(IV) derivatives. This coordination mode was further explored by DFT calculations, which showed that the bonding around the Sn center in [(C6H5)2Sn(L)2] was more asymmetric compared to the bonding around [(C6H5)(Cl)Sn(L)2]. However, the Sn-S bonds in [(C6H5)(Cl)Sn(L)2] were found to be more covalent than those in [(C6H5)2Sn(L)2]. Furthermore, the charge density of the frontier orbitals showed that the Sn atom in the complexes is relatively electrophilic and the Sn atom in [(C6H5)2Sn(L)2] has a lower atomic dipole moment than that of [(C6H5)(Cl)Sn(L)2]. The cytotoxicity and anti-inflammatory study revealed that [(C6H5)2Sn(L)2], with the higher number of phenyl substituents, has a higher potency than [(C6H5)(Cl)Sn(L)2]. The bio-efficacy study of these complexes as cytotoxic and anti-inflammatory agents showed that the complexes possessed moderate to high activity in comparison to the camptothecin and diclofenac in each case. Nevertheless, the diphenyltin(IV) derivative [(C6H5)2Sn(L)2] was found to possess a better activity than its counterpart due to the number of phenyl rings attached to the Sn center.

Synthesis, computational and biological studies of alkyltin(IV) N-methyl-N-hydroxyethyl dithiocarbamate complexes.

Methyltin(IV) of butyltin(IV)-N-hydroxyethyl dithiocarbamate complexes, represented as [(CH3)2Sn(L(OH))2] and [(C4H9)2Sn(L(OH))2] respectively were synthesized and characterized using spectroscopic techniques (1H, 13C and 119Sn NMR) and elemental analysis. Both infrared and NMR data showed that, the complexes were formed via two sulphur atoms of the dithiocarbamate group. This mode of coordination was further supported by the DFT calculation, which suggested the formation of a distorted octahedral geometry around the tin atom. The complexes were screened for their antioxidant, cytotoxicity and anti-inflammatory properties. Four different assays including DPPH, nitric oxide, reducing power and hydrogen peroxides were used for the antioxidant studies, while an in vitro anti-inflammatory study was done using albumin denaturation assay. The complexes showed good antioxidant activity, especially in the DPPH assay. Butyltin(IV)-N-hydroxyethyl dithiocarbamate showed better cytotoxicity activity compared to methyltin(IV)-N-hydroxyethyl dithiocarbamate in the selected cell lines, which included KMST-6, Caco-2 and A549 cell lines. The anti-inflammatory activities revealed that the two complexes have useful activities better than diclofenac used as control drug.

SnS2 and SnO2 Nanoparticles Obtained from Organotin(IV) Dithiocarbamate Complex and Their Photocatalytic Activities on Methylene Blue.

This work reports the photocatalytic degradation of methylene blue (MB) dye using SnS2 and SnO2 nanoparticles obtained from a solvothermal decomposition (in oleylamine) and pyrolysis (in a furnace) processes, respectively, of the diphenyltin(IV) p-methylphenyldithiocarbamate complex. The complex, which was used as a single-source precursor and represented as [(C6H5)2Sn(L)2] (L = p-methylphenyldithiocarbamato), was synthesized and characterized using various spectroscopic techniques and elemental analysis. The structural properties and morphology of the as-synthesized nanoparticles were studied using X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). UV-visible spectroscopy was used to study the optical property. The hexagonal phase of SnS2 and tetragonal SnO2 nanoparticles were identified, which exhibited varying sizes of hexagonal platelets and rod-like morphologies, respectively. The direct band gap energies of both materials, estimated from their absorption spectra, were 2.31 and 3.79 eV for SnS2 and SnO2, respectively. The photocatalytic performances of the SnS2 and SnO2 nanoparticle, studied using methylene blue (MB) as a model dye pollutant under light irradiation, showed that SnO2 nanoparticles exhibited a degradation efficiency of 48.33% after 120 min reaction, while the SnS2 nanoparticles showed an efficiency of 62.42% after the same duration of time. The higher efficiency of SnS2 compared to the SnO2 nanoparticles may be attributed to the difference in the structural properties, morphology and nature of the material's band gap energy.

PbS Nanoparticles Prepared Using 1, 10-Phenanthroline Adduct of Lead(II) Bis(N-alkyl-N-phenyl dithiocarbamate) as Single Source Precursors.

Dithiocarbamate complexes have remained prominent as single source precursors for the synthesis of clean metal sulfide nanoparticles. This study reports the synthesis of lead sulfide (PbS) nanoparticles using some novel complexes of 1, 10-phenanthroline lead(II) bis(N-alkyl-N-phenyl dithiocarbamate), represented as [Pb(L1)2phen] (1) and [Pb(L2)2phen] (2) (where L1 = bis(N-ethyl-N-phenyldithiocarbamate; L2 = bis(N-butyl-N-phenyldithiocarbamate); phen = 1, 10 phenanthroline) as a single source precursors. The complexes (1 and 2) were synthesized and characterized using various spectroscopic techniques and elemental analysis. The nanoparticles were synthesized via a solvothermal approach in oleylamine, used as a capping agent, and were given as PbS(1) and PbS(2) from [Pb(L1)2phen] (1) and [Pb(L2)2phen] (2), respectively, which were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and absorption spectroscopy. The diffraction patterns confirmed the formation of face-centered cubic phase PbS nanoparticles with a preferential growth orientation along the (200) plane. The TEM images showed that PbS(1) were of a spherical morphology, while the morphology of PbS(2) tended to produce short rods. This was due to variation in the functional group on the precursor compounds. This variation also resulted in the different band gap energies found such as 1.148 and 1.107 eV for PbS(1) and PbS(2), respectively, indicating a blue shift from the bulk.

Chemistry and Some Biological Potential of Bismuth and Antimony Dithiocarbamate Complexes.

Interest in the synthesis of Bi(III) and Sb(III) dithiocarbamate complexes is on the rise, and this has been attributed to their wide structural diversity and their interesting application as biological agents and in solid state/materials chemistry. The readily available binding sites of the two sulphur atoms within the dithiocarbamate moiety in the complexes confers a wide variety of geometry and interactions that often leads to supramolecular assemblies. Although none of the bismuth or antimony metals are known to play any natural biological function, their dithiocarbamate complexes, however, have proven very useful as antibacterial, antileishmanial, anticancer, and antifungal agents. The dithiocarbamate ligands modulate the associated toxicity of the metals, especially antimony, since bismuth is known to be benign, allowing the metal ion to get to the targeted sites; hence, making it less available for side and other damaging reactions. This review presents a concise chemistry and some known biological potentials of their trivalent dithiocarbamate complexes.

Organotin(IV) Dithiocarbamate Complexes: Chemistry and Biological Activity.

Significant attention has been given to organotin(IV) dithiocabamate compounds in recent times. This is due to their ability to stabilize specific stereochemistry in their complexes, and their diverse application in agriculture, biology, catalysis and as single source precursors for tin sulfide nanoparticles. These complexes have good coordination chemistry, stability and diverse molecular structures which, thus, prompt their wide range of biological activities. Their unique stereo-electronic properties underline their relevance in the area of medicinal chemistry. Organotin(IV) dithiocabamate compounds owe their functionalities and usefulness to the individual properties of the organotin(IV) and the dithiocarbamate moieties present within the molecule. These individual properties create a synergy of action in the hybrid complex, prompting an enhanced biological activity. In this review, we discuss the chemistry of organotin(IV) dithiocarbamate complexes that accounts for their relevance in biology and medicine.