Mussel-inspired nano-silver loaded layered double hydroxides embedded into a biodegradable polymer matrix for enhanced mechanical and gas barrier properties

Nanoarchitectured two-dimensional layered double hydroxides-based nanocomposites for biomedical applications

Despite the exceptional physicochemical and morphological characteristics, the pristine layered double hydroxides (LDHs), or two-dimensional (2D) hydrotalcite clays, often suffer from various shortcomings in biomedicine, such as deprived thermal and chemical stabilities, acid-prone degradation, as well as lack of targeting ability, hampering their scale-up and subsequent clinical translation. Accordingly, diverse nanocomposites of LDHs have been fabricated by surface coating of organic species, impregnation of inorganic species, and generation of core-shell architectures, resulting in the complex state-of-the-art architectures. In this article, we initially emphasize various bothering limitations and the chemistry of these pristine LDHs, followed by discussions on the engineering strategies of different LDHs-based nanocomposites. Further, we give a detailed note on diverse LDH nanocomposites and their performance efficacy in various biomedical applications, such as drug delivery, bioimaging, biosensing, tissue engineering and cell patterning, deoxyribonucleic acid (DNA) extraction, as well as photoluminescence, highlighting the influence of various properties of installed supramolecular assemblies on their performance efficacy. In summary, we conclude with interesting perspectives concerning the lessons learned to date and the strategies to be followed to further advance their scale-up processing and applicability in medicine.

Direct contact, dissolution and generation of reactive oxygen species: How to optimize the antibacterial effects of layered double hydroxides

Infections by pathogenic bacteria have been threatening several fields as food industries, agriculture, textile industries and healthcare products. Layered double hydroxides materials (LDHs), also called anionic clays, could be utilized as efficient antibacterial materials due to their several interesting properties such as ease of synthesis, tunable chemical composition, biocompatibility and anion exchange capacity. Pristine LDHs as well as LDH-composites including antibacterial molecules and nanoparticles loaded-LDHs were proven to serve as efficient antibacterial agents against various Gram-positive and Gram-negative bacterial strains. The achieved antibacterial effect was explained by the following mechanisms: (1) Direct contact between the materials and bacterial cells driven by electrostatic interactions between positively charged layers and negatively charged cell membranes, (2) Dissolution and gradual release over time of metallic ions or antibacterial molecules, (3) Generation of reactive oxygen species.

Mussel-Inspired Approach to Constructing Dual Network Coated Layered Clay for Enhanced Barrier and Antibacterial Properties of Poly(vinyl alcohol) Nanocomposites

Inspired by complexation and mussel adhesion of catechol groups in tannic acid (TA), organophilic layered double hydroxides (LDHs@TA-Ti) were synthesized by forming a one-pot assembled TA-titanium (Ti) dual network coating on the surface of layered clay for the first time. LDHs@TA-Ti/poly(vinyl alcohol) (PVA) nanocomposites were prepared by the solution casting method. The results show that TA-Ti(IV) and TiO2 coordination compounds are simultaneously formed due to hydrolysis of titanium tetrachloride and complexation of TA in aqueous solution. Upon TA-Ti coatings onto the surface of LDHs, the antibacterial rate of LDHs@TA-Ti is up to 99.98%. Corresponding LDHs@TA-Ti/PVA nanocomposites also show outstanding antibacterial properties. Compared with pure PVA, LDHs@TA-Ti/PVA nanocomposites show a 40.9% increase in tensile strength, a 17.5% increase in elongation at break, a 35.9% decrease in oxygen permeability and a 26.0% decrease in water vapor permeability when adding 1 wt % LDHs@TA-Ti. UV transmittance (at 300 nm) of LDHs@TA-Ti/PVA nanocomposites decrease by 99.4% when the content of LDHs@TA-Ti reaches 3 wt %. These results indicate that PVA matrix incorporated with LDHs@TA-Ti could be used as a potential active packaging material to extend the shelf life of food products.

Recent innovations in functionalized layered double hydroxides: Fabrication, characterization, and industrial applications

Layered Double Hydroxides (LDHs) are a group of hydrotalcite-like nano-sized materials with cationic layers and exchangeable interlayer anions. The wide range of divalent and trivalent cationic metals and anionic compounds are employed in the synthesis of LDH materials, which have improved their importance among the researchers. Because of their high anion exchange property, memory effect, tunable behavior, bio-friendly, simple preparation, and their affordability, these nano-materials are essentially interested today. Modification of LDHs improves their behaviours to make them appropriate in industrial fields, including biological, adsorbent, mechanical, optical, thermal, electrical fields, etc. This review has critically discussed the structural features, main properties, and also clarified the most important methods of modification and intercalation of LDH nano-materials. Moreover, some novel reported researches related to the successful modification of LDH materials have been characterized and briefly the advantages, disadvantages, and applications are presented in the industrial fields.

Layered double hydroxide nanostructures and nanocomposites for biomedical applications

Layered double hydroxide (LDH) nanostructures and related nanocomposites have attracted significant interest in biomedical applications including cancer therapy, bioimaging and antibacterial treatment. These materials hold great advantages including low cost and facile preparation, convenient drug loading, high drug incorporation capacity, good biocompatibility, efficient intracellular uptake and endosome/lysosome escape, and natural biodegradability in an acidic environment. In this review, we summarize the development of three types of LDH nanostructures including pristine LDH, surface modified LDH, and LDH nanocomposites for a range of biomedical applications. The advantages and disadvantages of LDH nanostructures and insights into the future development are also discussed.

Morphology, Thermal Stability, and Flammability Properties of Polymer-Layered Double Hydroxide (LDH) Nanocomposites: A Review

The utilization of layered nanofillers in polymer matrix, as reinforcement, has attracted great interest in the 21st century. This can be attributed to the high aspect ratios of the nanofillers and the attendant substantial improvement in different properties (i.e., increased flammability resistance, improved modulus and impact strength, as well as improved barrier properties) of the resultant nanocomposite when compared to the neat polymer matrix. Amongst the well-known layered nanofillers, layered inorganic materials, in the form of LDHs, have been given the most attention. LDH nanofillers have been employed in different polymers due to their flexibility in chemical composition as well as an adjustable charge density, which permits numerous interactions with the host polymer matrices. One of the most important features of LDHs is their ability to act as flame-retardant materials because of their endothermic decomposition. This review paper gives detailed information on the: preparation methods, morphology, flammability, and barrier properties as well as thermal stability of LDH/polymer nanocomposites.