KROS Publications 198 www.ijacskros.com Functionalized Layered Double Hydroxide (LDHs) Nanohybrids for Drug Delivery Applications B. Adi Lakshmi 1 , Chandra Sekhar Espenti , K.S.V. Krishna Rao *, B. Vijaya Kumar Naidu 1 Polymer Biomaterial Design and Synthesis Laboratory, Department of Chemistry, Yogi Vemana University, Kadapa, Andhra Pradesh, India, 2 Department of Chemistry, Sreenidhi University, Yamnampet, Hyderabad, Telangana, India, 3 Department of Materials Science and Nanotechnology, Yogi Vemana University, Kadapa, Andhra Pradesh, India 1. INTRODUCTION Polymer matrices are typically supplemented with inorganic fllers to improve their properties and expand their applications [1]. Well-known fllers include silicate, calcium carbonate, fbers, and carbon-based structures. It is evident that a high fller content is required to have a signifcant impact on the properties of polymer matrices. In most cases, a higher fller component increases the weight of the produced composites, restricting the applications of such devices. To overcome the weight issue, nanoparticles have recently emerged as the preferred fller for improving the properties of the resulting polymer matrix. This is due to ability of nanoparticles to change the properties of a polymer matrix with relatively modest concentrations, allowing nanocarriers to maintain the density of the polymer matrix low. The incorporation of layered inorganic fllers into polymer matrices to form polymer/layered inorganic nanocomposites has sparked a lot of attention due to its unique properties [2]. Layered double hydroxides (LDHs)/polymer nanocarriers are an important family of polymer/layered inorganic nanocomposites because they improve thermal stability, flame retardancy, and overall physical properties [3,4]. Due to the enormous pressure that could limit or prevent the use of halogen flame-retardant materials due to environmental concerns and LDHs have emerged as a viable option for halogen-free flame-retardant material [5-7]. Urea hydrolysis, hydrothermal synthesis, co-precipitation, and ion exchange are some of the methods utilized to manufacture LDH that have been widely documented in the literature [8,9]. LDH has the following structure in terms of chemistry: [Ax/m m•nH 2 O] intra [MII 1x Mx III (OH) 2 ] inter [Figure 1]. The intralayer crystallographic domain and interlayer spaces are represented in the formula by the terms inter and intra. The layers of LDHs are positively charged edge-shared octahedral coordinated metal hydroxide crystal formations sandwiched by charge-compensating interlayer anions and, as an alternative, water solvation. MII (M 2+ ) is a divalent cation, MIII (M 3+ ) is a trivalent cation, and A is an anion with m-valency. When compared to well-known layered silicates, LDHs have a high charge density in the interlayer and appear to have an impermeable effect between the hydroxides, making exfoliation extremely difficult [10]. Furthermore, because polymers are hydrophobic, polymer chains are more difficult to incorporate into LDHs. To improve polymer intercalation in LDH layers, anionic materials must be utilized. The simplest and ABSTRACT Biomedical research involving layered double hydroxide (LDH) nanohybrid materials has received a lot of attention. These LDH nanohybrid materials have distinct properties such as biocompatibility, variable chemical compositions, anion-exchange capacity, host-guest interactions, and crystallization-dissolution properties. Drug delivery is becoming increasingly important because it enables theranostics (therapeutics and diagnostics), a concept of next-generation medicine, to combine therapy and diagnosis. Based on the unique properties of LDH-based nanohybrid materials open up new avenues for simultaneous therapy and drug release applications in almost every feld of medicine. The purpose of this chapter is to investigate recent advances in multifunctional LDH nanohybrid materials, ranging from fabrication to drug molecule release applications in various bio- medical felds with therapeutic functions. Furthermore, these (LDH) nanohybrid materials have the potential to be used as both diagnostic agents and drug delivery carriers and there will be discussed in relation to advancements in bio-medical systems. Due to their exceptional physiochemical properties, two-dimensional LDHs nanohybrid materials are currently a fascinating topic of interest. LDHs have the potential to be useful in a variety of applications, such as energy, catalysis, and biomaterials; particularly in the bio-medical feld as drug delivery systems. Despite the unique intrinsic properties of LDH nanohybrid materials, various functionalization strategies have been applied to LDHs, yielding even more exciting performance opportunities and providing guidelines for the design of novel functional nanomaterials. Key words: Layered double hydroxide, Nanohybrids, Drug delivery, Bio-materials and Bio-medical applications. Indian Journal of Advances in Chemical Science Article *Corresponding author: K.S.V. Krishna Rao E-mail: ksvkr@yogivemanauniversity.ac.in ISSN NO: 2320-0898 (p); 2320-0928 (e) DOI: 10.22607/IJACS.2023.1103006 Received: 27 th April 2023; Revised: 18 th June 2023; Accepted: 25 st June 2023.