Overview of Nano-Strategies for Combating Cancer

Introduction

Nanotechnology has been a well-known research field since the last century. In 1959, the physicist Richard Feynmann (Richard, 1959) suggested a new area of research for science & technology on an atomic and molecular scale in a paper entitled “There's Plenty of Room at the Bottom.” Since “nanotechnology” was named. Nanotechnology developed nanoscale-level materials of different forms. Nanoparticles (NPs) are broad nanomaterials with dimension of 1-100 nm (Laurent et al., 2008). Those materials can be 0D, 1D, 2D, or 3D depending on the overall shape (Tiwari et al, 2012). The importance of these materials became conscious when researchers exposed that dimensions can influence a material physicochemical properties, e.g. the optical properties. NPs of 20-nm Au (gold), Ag (silver) Pt (platinum), and Pd (palladium) have characteristic colour of red wine, yellowish gray, black, and dark black, respectively. Figure- 1 indicates that the diagram is an example, in which gold NPs synthesis with different sizes. Such NPs exhibited significant colors and characteristics with the variability in size and shape that can be used in bioimaging applications (Dreaden et al., 2012). Figure-1 shows that the colour of the solution varies because of difference in aspect ratio, nanoshell thickness and gold concentration percentage. Any modification in an element's physical properties affects the absorption properties of the NPs, and also has different colours.

Figure 1.

Colour variation of Gold NPs with respect to size and shape (Dreaden et al, 2012)

NPs are composed of three layers i.e. outer layer, shell layer or inter intermediate layer and the inner core. The outer layer is composed with diverse molecules like metal ions, polymers and surfactants, he shell layer or intermediate layer, which is distinct from the core material, and the core; which is fundamentally central part of a NP and refers specifically to the NP as its own (Shin et al., 2016).

The above materials got tremendous interest among researchers in different disciplines because of such unique properties. Figure-2 Shows images of mesoporous and non-porous methacrylate functionalized silica (MA-SiO₂) by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Other characteristics of mesoporosity are imparted in NPs. The NPs are used for the delivery of drugs (Yamauchi et al, 2008), chemical and biological sensing (Barrak et al., 2019), gas sensing (Mansha et al., 2016), CO₂capture (Rawal et al., 2013), and other related applications (Khan et al., 2017).

Figure 2.

FE-SEM micrographs of (a) nonporous MA-SiO₂ NPs, (b) mesoporous MA-SiO₂ NPs. TEM images of (c) nonporous MASiO₂NPs and (d) mesoporous MA-SiO₂ NPs (Lee et al., 2011)