Cancer treatment by chemotherapeutics often results in off-target effects. To minimize the adverse effects of chemotherapy, multiple ways of achieving targeted drug delivery have evolved. Antibody-drug conjugates (ADCs) are one such class of drugs. However, development of new ADCs is challenging and not generalizable. In this dissertation, we utilize antibody-nanoparticle conjugates (ANCs) to address the limitations of ADCs as well as to develop a platform technology toward achieving targeted delivery of chemotherapeutics to cancer cells. In this dissertation, we have also set the groundwork for utilizing proteins/antibodies as drugs for cancer therapy. Two different nanoparticle systems were developed for (a) achieving targeted delivery of proteins to cancer cells selectively and (b) efficient intracellular delivery of large proteins such as antibodies. Extending the applicability of antibody-conjugated polymeric nanoparticle, anionic polymer-antibody conjugates were formulated for developing a technique to achieve targeted electroporation of biologics into cancer cells.