Lately, metallic nanoparticles have been earning vast applications in drug deliv-

ery. These nano-metallic particles can be synthesized and further engineered with

various chemical moieties, enabling the conjugation(s) with varied antibodies,

functional moieties, ligands and apt drugs (Mody et al. 2010; Lena Leopold et al.

2018). These nanoparticulates have immense significance in the field of biotechnol-

ogy, targeted drug delivery of drugs and biologics and diagnostic imaging. Molar

fraction of reactants during the synthesis of metallic nanoparticles along with the

conditions thereof comprises the CMAs and CPPs, which regulate their yield, size,

size distribution and drug loading as the major CQAs (Mody et al. 2010; Singh et al.

2018a, b).

Of late, carbon-based nanostructures have been explored as potential drug deliv-

ery carriers owing to their innumerable applications. Carbon nanotubes (CNTs) act

as a promising carbon-based nanostructured systems owing to their higher surface

area, superior electric and thermal conductivities and high mechanical strength

(Baughman et al. 2002). Their hollow and nanoscale tube-shaped structure enables

high loading of variegated drug molecules through their possible conjugation with

the nanotube walls. Key CMAs/CPPs employed for systematic development of

functionalized CNTs encompass reaction time and temperature, reacting material

concentrations, which have substantial impact on yield, solubility and drug loading

of the functionalized CNTs (Sun et al. 2002). Quantum dots, which constitute a vital

class of delivery systems with nanometric particle size, are semiconductor particles

for theranostic applications (Bera et al. 2010; Tripathi et al. 2015).

A recent literature survey of the top most journals revealed remarkably high rate

of publications in this multi-, cross- and interdisciplinary field of nanomedicine. For

an arena evolving as fast as this one, it is relatively challenging to acquire a

comprehensive overview of the active developments, as most updated and organized

information on such nano-bio interfaces lies scattered in various journals. Over the

past few decades, applications of nanoparticles in biotherapeutics have become a

highly distinct and dynamic area of scientific and technological development. A

deluge of publications in the recent literature testifies that the scenario of science and

research in drug delivery has been fast transitioning with a shift from micro- to

nanonization. Drug nanoconstructs offer a more convenient alternative to the dis-

covery of new drugs, which involve huge investments not only in terms of money

but also in terms of manpower and time. In contrast, repackaging or remodelling the

existing molecules of established therapeutic potential using nanostructured carrier

systems can suitably address issues like solubility, stability, permeability, metabolic

degradation, fast clearance and adverse effects, which tend to limit their effective-

ness. In addition, the resulting product is relatively more protectable from patent-

ability perspectives and is readily commercially available, because of the “newness”

imparted to it.

Besides the development of their formulation, the constancy in terms of stability

of these nanoconstructs is measured as quite critical characteristic to assess timely

and assure. Based upon the chemistry and electromagnetic nature of the

nanoparticles, these may occur as colloids, dispersed aerosols, suspensions or in

an agglomerative state. Furthermore, as a function of the size of the agglomerates,

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QbD-Steered Systematic Development of Drug Delivery Nanoconstructs:. . .

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