Nano Metal Based Herbal Theranostics for Cancer Management: Coalescing Nature's Boon with Nanotechnological Advancement.

Cancer is amongst the leading public health problems globally with continuously increasing prevalence rate that demands for extensive and expensive treatment. Despite availability of number of potential cancer therapies, inadequate success has been achieved due to complexity and heterogeneity of tumors. Moreover, late/ terminal stage cancer leads to multidrug resistance, excruciating side effects, recurrence, etc. This is because of low penetrability and deleterious effects of drug on non-target cells/ tissues. This requires for cost effective, efficacious, alternative/ adjunct, complementary medicines with targeted drug delivery approach. A potential strategy to resolve this difficulty is to use theranostics i.e., formulations having both a therapeutic element and an imaging agent. Phytotherapeutics have been extensively used since times immemorial, having wide acceptability, easy availability, minimal side effects and comparatively inexpensive. These herbal formulations are mostly orally administered and thus subjected to adverse pH, enzymatic degradation, poor gut absorption, low bioavailability and non-targeted delivery that ultimately lead to their poor effectiveness. Constraints associated with conventional phyto-pharmaceuticals can be improved by designing and using "Nano Delivery Systems" (NDS). The foremost aim of metal based NDS is to provide sustained drug release, site-specific action, improved patient's compliance and enhanced efficacy. Metal Nanocarriers carrying herbal drugs will avoid these obstructions, so the drug can circulate into the blood for a longer period of time and provide optimal amount of the drug to the site of action. Besides, herbal drugs with NDS thus would be efficacious as alternative/ complementary cancer theranostics. Present review describes novel theranostic systems employing metal nanocarriers with diagnostic and therapeutic properties as an effective strategy for cancer treatment. These systems when conjugated with herbal drugs provide an efficient management strategy for cancer.