FABRICATION OF BIOACTIVE GLASS BASED ORALLY ADMINISTERED DRUG CARRIERS FOR BONE REGENERATION

Abstract

Bone disorders are one of the most prevalent diseases throughout the world, ranking Asia among the top list of people suffering from Osteoporosis (OP), especially women. There is an accelerated increase in OP during early postmenopausal years. Other prevalent bone disorders include osteomalacia, osteoarthritis, osteopenia, osteomyelitis, osteodystrophy, etc. The main cause for the prevalence of OP is the reduction of the organic matrix of bones i.e. protein leading to the fragility of bone and ultimately breaking of the bone. Treatment of bone disorders includes various techniques and measures like collagen fillers, collagen injections, tissue grafts (autograft, allograft), bone implants, tissue engineering, health supplements, etc. With the advent of third-generation biomaterial, bioactive glass (BG) has been widely used for bone regeneration as scaffolds and tissue engineering as it stimulates the natural bone to repair itself. In this view, emphasis is laid on the targeted oral delivery of protein and nutrients along with bioactive glass for bone regeneration using a polymeric matrix. To the best of our knowledge, it is the first time that oral delivery of bioactive glass is carried out for bone health applications due to its osteoinductive and osteoconductive properties. Also, BG is the reservoir of essential micronutrients that are essential for bone mineralization. For this, the synthesis of Nano-sized BG particles is carried out and it is radiolabelled with Technetium-99m (Tc-99m) and the labeling efficiency is calculated at different pH ranges. BG formed is found to be bioactive and biocompatible and is easily taken up by the intestinal cell lines (Caco-2). These studies made these nanoparticles a suitable candidate for oral drug delivery application. To provide complete nutrition for overall bone health various edible protein films have been fabricated fortified with BG network and essential vitamins like vitamin D and vitamin K. We have explored the application of BG in drug delivery and as functional food by carrying out in-situ mineralization of bioactive glass in food-grade polymer for targeted protein delivery and fabrication of bioactive glass fortified functional food for bone health respectively. The materials thus formed are tested for cytocompatibility and found to be biocompatible. Finally, to protect against micro-organisms and pathogens and to prevent photo-oxidation, the active packaging material is fabricated that can be used for the packaging of the drug and food. Further, the radiolabeling of BG and its binding stability in different gastrointestinal pH conducted in the present study can be explored in the future in an animal model where the whole ADME process (Absorption, Distribution, Metabolism, and Excretion) can be studied when these particles are ingested orally. The pharmacokinetics and pharmacodynamic studies will help in deducing the efficacy of bioactive glass through the oral route in bone regeneration. This thesis is summarized in five chapters. Chapter 1 Discusses a brief introduction to bone disorders and their prevalent treatments. It also talks about the application of biomaterials and the advantages of bioactive glass for bone regeneration applications. Chapter 2 This chapter describes the synthesis, characterization, and functionalization of bioactive glass nanoparticles through an in-situ mineralization process. Physico-chemical characterization is carried out to investigate the morphology, crystallinity, and functionality of the nanoparticles. An in-vitro cell proliferation assay is conducted to check the cytocompatibility against caco-2 and U2OS cell lines. The cellular uptake studies of the said nanoparticles for caco-2 cell lines are studied to prove it to be an efficient oral delivery nanocarrier. The radiolabeling efficiency of 99mTc with formed nanoparticles is monitored at different pH levels at various time intervals. Thus, this work demonstrated the fabrication of biomaterial that can be employed as a potent radiopharmaceutical for long-term follow-up studies and in-vivo imaging. Chapter 3 The present chapter focuses on fabricating sandwiched film as a controlled drug delivery system using dextran for the delivery of collagen and vitamin D along with bioactive glass to the colon site. To provide both organic and inorganic nutrients to the bone framework, in-situ mineralization of the bioactive glass network is carried out in a collagen matrix and is cast into a film. This film is sandwiched between the dextran film as the latter is considered to be important in colon-specific delivery. CD spectra depict the conformational changes in the secondary structure of collagen due to the inter- and intramolecular interactions of the BG network with the collagen fibrils. The rheological study is done to depict the visco-elastic nature of the sandwiched film in different GI tract pH. UV-Visible spectroscopy reveals the release of vitamin D and collagen at pH 6.8. The SDS-PAGE profile helps deduce the targeted delivery of collagen at the colon site having pH 6.8. Cellular cytotoxic studies are employed to deduce the biocompatible nature of the film. Chapter 4 The chapter focuses on the fabrication of soy films as a functional food for bone nutrition. The film formed is fortified with an in-situ mineralized bioactive glass (BG) network containing essential minerals required for good bone health. Also, vitamin K1 is supplemented into the films. Nutritional analysis is carried out to show that the films are a rich source of protein containing about 67% of protein per 100 g having energy calories of 330 Kcal/100 g and essential micronutrients required for bones. The rheological studies are conducted for the functional soy-based film. The mechanical analysis of the formed film is done along with its antimicrobial assay. Chapter 5 A comprehensive study on Zein film blended with glycerol and essential oils (EOs) is presented in this work. In particular, UV shielding properties and antimicrobial efficacy of developed active zein films are tested. Antibacterial assays are conducted to prove that the films are effective against spoilage microorganisms. Thermal and mechanical characterization of the film is carried out. To deduce its efficacy as packaging/coating material, water vapor permeability testing, and oxygen transmission rate are also investigated.