Evolving Trends of Nanotechnology for Medical and Biomedical Applications: A Review Sravan Bokka and Anirban Chowdhury, Indian Institute of Technology, Patna, Bihar, India r 2021 Elsevier Inc. All rights reserved. Key Terms Hydrogel and shape memory materials based on polymer nanocomposites for drug delivery, tissue engineering and associated medical and biomedical applications. Introduction The use of nanotechnology has become an essential (and unavoidable) tool in medical and biomedical sector. Nanotechnology can provide numerous solutions for advanced technological applications, e.g., in the field of medical and biomedical research. Some of those applications involve tumour/cancer treatment with imaging, tissue regeneration, targeted drug delivery, bio- implants and prosthesis etc., (Bhushan, 2017; Poole and Owens, 2003; Chen et al., 2013; Teo et al., 2016; Bozukova et al., 2010). Many of these applications involve nanocomposites with polymer matrices and metallic/ceramic/inorganic nanofillers. Although the amount of the nanofillers used for such nanocomposites are very low (o5 vol%), the special properties displayed by the filler hold the key to the success for these PNCs (Venkatesan and Kim, 2014; Armentano et al., 2010; Liu et al., 2007). For example, Fe- oxide nanoparticles are known for their higher magnetic susceptibility at negligible coercivity (superparamagnetism) (Kalia et al., 2014; Song et al., 2014). These superparamagnetic Fe-oxides have shown immense potential as a nanofiller (NF) in PNCs (for applications involving temperature responsive and magnetic responsive hydrogels) (Kalia et al., 2014; Mohr et al., 2006; Das et al., 2013; Gil and Hudson, 2004). In other words, these hybrid systems at nanoscale can offer a unique combination of magnetic and thermal responses that are suitable for medical use (Song et al., 2014; Ferreira et al., 2018; Obiweluozor et al., 2017). Another popular medical application pertains to drug delivery. Once again, science and technological innovations at modern times provide exclusive solutions to tailor-made optimised carrier. In this connection, nano-metallic systems have shown tremendous potential owing to their special size dependent features. Gold nanoparticles are one of such successful system that have been tried for different medical research innovations (Chen et al., 2013). Their non-toxic nature together with distinctive optical, biological, physical and chemical properties have made them as a popular choice for many drug delivery and associated bio-medical applications involving polymer matrices (Chen et al., 2013; Small et al., 2005). In this book chapter, we aim to highlight (and summarize) major important PNCs for various ranges of medical and biomedical applications. Our focus will be devoted to highlight the road of various types of nanofillers that are being used making such PNCs. Use of PNCs with various biomedical applications, e.g., medical imaging to cancer therapy, drug delivery to tissue engineering, antibacterial ointments to antimicrobial mats, etc., (Feldman, 2016; Tiwari et al., 2012; Ratner and Bryant, 2004) have been shown in Fig. 1 and Table 1. Polymer Nanocomposites (PNCs) The term medical science deal with study of body, diseases and their interaction with persons, diagnose, cure while biomedical engineering focuses more with the application aspects of medical science (diagnose and cure etc.,). PNCs (macromolecular polymer matrix with reinforced nanofillers) are generally found to exhibit superior and tailored properties compared to the micro and macro-polymer composites (Feldman, 2016; Tiwari et al., 2012). The benefit of nanofillers and their interactions with the matrix is pushing PNCs for better properties/characteristics over macro and micro-polymer com- posites (Feldman, 2016). In the medical field, polymers are mostly used because of their physical properties, biocompatibility and biodegradability with respect to human body; key systems involve polyglycolides (PGA), polylactide, poly (e-caprolactone) (PCL), chitosan, etc., (Feldman, 2016; Tiwari et al., 2012). The popular nanofillers used for these applications are mostly metals or minerals. Examples of relevant metallic nanofillers include copper (Cu), silver (Ag), gold (Au), platinum (Pt), titanium (Ti), palladium (Pd), etc., (Chen et al., 2013; Song et al., 2014; Das et al., 2013; GhavamiNejad et al., 2016; Diez-Pascual and Diez- Vicente, 2015a,b). Among compound fillers important examples involve bi-metallics, metal oxides, ferrites, superparamagnetic iron oxide nanoparticles (SPIONs), etc., (Song et al., 2014; Ratner and Bryant, 2004; Zhou et al., 2017; Ponnamma et al., 2019). Within the class of mineral fillers, clays such as kaolinite, montmorillonite (MMT), sepiolite, halloysite, palygorskite etc., are noteworthy (Warren et al., 2017; Gaharwar et al., 2013). The colloidal dimensions and high surface area of these mineral fillers makes them efficient for medical and biomedical applications (Feldman, 2016). Fig. 2. shows both natural and synthetic biopolymers relevant for PNC-related applications. Both the variants have their own merit/s and demerits. Natural biopolymers are known for better biological recognition and thus gives an advantage in terms of cell Encyclopedia of Materials: Plastics and Polymers doi:10.1016/B978-0-12-820352-1.00098-5 1