Antibody-Functionalized Inorganic NPs: Mimicking Nature for Targeted Diagnosis and Therapy - Bioinspired Approaches for Human-Centric Technologies - page 3

Alternatively, the presence of thermolabile molecules (i.e., azo or peroxide groups,
which can be decomposed above a certain temperature), placed in between the
nanoparticle surface and the drug molecule, can promote the release “on demand”
of the drug agents, as soon as sufficient heat is generated locally, i.e., at the
nanoparticle surface. Moreover, some nanomaterials can be also applied as imaging
probes in diagnostic applications (Sun et al. 2008 ; Corot et al. 2006 ; Michalet
et al. 2005 ). Magnetic nanoparticles indeed can be employed as contrast agents in
molecular resonance imaging (MRI), while semiconductor nanocrystals can be
used as optical probes when excited by the light.
In all these biomedical applications, specific delivery based on active targeting
toward antibody-antigen coupling is always desired. In this way, accumulation
toward the target in cancer therapy is ensured, so that the total dose of the nano-
therapeutic agents is reduced and the side effects are minimized. Additionally,
nonspecific distribution in imaging applications is also avoided, thus making the
imaging technique more sensitive.
Nanotechnology is already taking advantages of the monoclonal antibody ther-
apy, as documented by the increasing number of works in literature on antibody-
nanoparticle (Anb-NP) formulations. Merging such inorganic nanomaterials with
antibodies will contribute to the development of intelligent multifunctional nano-
therapeutic and nano-diagnostic tools that are more specific toward their targets
than the corresponding nonfunctionalized nanoparticles.
In this chapter, we will provide an overview of the current state of the art in the
preparation of antibody-functionalized nanocrystals and their application in the
biomedical fields. This will include the critical steps related to the preparation of
antibody-nanoparticle conjugates via different binding chemistries. Many aspects
of the chemistry of conjugation between the surface of the nanocrystals and the
antibodies have been understood in detail, and a considerable amount of work has
tackled the challenge of synthesizing antibody-nanoparticle conjugates while
maintaining the high specificity, avidity, and targeting performances. The results
of these efforts have led to fabrication of new multifunctional imaging, sensing, and
therapeutic tools. At the current state of the art, antibodies have been extensively
exploited as shuttles for carrying chemotherapeutic agents or radioisotope drugs
directly to the tumor, and many of these products have already reached the clinic.
However, in the case of inorganic nanoparticles functionalized with antibodies,
formulations are still in a preclinical stage. Some selected examples of in vivo
applications of antibody-functionalized nanocrystals will be additionally provided,
together with our considerations on the critical issues to be taken into account when
using such nano-formulations.