Conclusions

The central hypothesis of this thesis is development of biocompatible multifunctional MNPs and its biological theragnostic applications. Magnetic- based theragnostic NPs are of significant interest in cancer nanotechnology owing to the abundant advantages these materials possess in the presence of a magnetic field. The development of multifunctional MNPs with biocompatibility can enhance the interaction and can be exploited for both active and passive imaging, MRI, drug delivery and magnetic hyperthermia for the destruction of cancer cells. MNPs are of great relevance for researchers from a wide range of disciplines, such as magnetic fluids, data storage, catalysis, and bioapplications. The consummation of the data gathered in this thesis considering the application of MNPs for cancer therapy in conjugation with diverse nanosystem, presents this extremely adept MNPs as a future nanotool with tremendous potentials to not only destructing the tumors via MHT, but also arresting their threatening recurrence of cancer by tailoring the multifunctionality part.

The ultimate goal of the investigation is the curbing of proliferation of cancer cells with multifunctional MNPs. We enhanced the biocompatibility of MNPs by efficiently coating with different biopolymers (Carboxymethyl cellulose, bacterial exopolysaccharides and PLGA). The multifunctionality to polymer coated MNP was rendered by efficiently attaching functional groups for biorecognition by cancer cells.

The magnetic functionality has been exploited to render the MNP a diagnostic tool and targetable nanodrug carrier for cancer therapy. In short the extraordinary properties of multifunctional MNPs such as the application of the same for magnetic targeting, controlled drug delivery and in magnetic hyperthermia were investigated.

The exceptional nanocombination of MNPs, drugs (5-FU, Gemcitabine and Curcumin), targeting ligands (Folate, Transferrin, Anti HER2 antibody and AS1411 aptamer), and imaging agents (FITC, SYPRO ruby, Curcumin) permitted the nanoconjugate to be located within the cancer cells and triggered the release of drugs to target cells, thus facilitating imaging to be combined with efficient therapy.

The elaborated conclusion of experiment is presented in detail.

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Carboxy methyl cellulose-MNPs as theragnostic agents

In this study a multifunctional CMC based nanovector tailored for targeting, imaging and efficient delivery of therapeutic agent was developed. The nanovector was targeted to tumor marker- folate receptor that was overexpressed in cancer cells. Our nanovector co-delivered superparamagnetic fluorescent NPs and a potential therapeutic agent to cancer cells. The potential anti cancerous drug, 5-FU was encapsulated and was released in a sustainable manner over a period of 60 h.

The combined treatment of cancer cells with targeted drug loaded CMC MNPs and MHT synergistically killed almost 95 % of cancer cells. The collective results of (a) The biocompatibility of the CMC MNPs (low cytotoxicity with drug free CMC MNPs) and (b) The huge decrease in the viability of cancer cells after the simultaneous exposure of drug and application of an alternating magnetic field suggest that drug loaded CMC MNP could be used as efficient nanovector against cancer. In addition the fluorescent CMC MNPs was also exploited for cancer cell imaging thus tailoring these NPs as theragnostic nanovector.

Bacterial exopolysaccharide coated MNPs

We exploited the potential of bacterial EPS (MR and GG) as biocompatible coating for MNPs. We have developed multifunctional bacterial EPS (MR and GG) based MNP and was tailored for targeting; imaging and for efficient delivery of therapeutic agent. EPS coated MNPs were targeted to tumor marker- folate receptor, which was overexpressed specifically in cancer cells. EPS coated NPs co-delivered superparamagnetic fluorescent NPs and a chemotherapeutic agent to cancer cells. The synergistic treatment of cancer cells with targeted drug loaded MR-MNPs and GG-MPS and MHT specifically destroyed almost 80 % of cancer cells within short period of time. The labeling of fluorescent moiety to EPS generated an additional advantage of exploitation of imaging cancer cell thus modifying these NPs to theragnostic nanocomposite for efficient treatment for deadly cancer. The observed biocompatibility and low cytotoxicity of MR-MNPs and GG-MNPs and the enormous decrease in the viability of cancer cells after the synchronized exposure of drug and application of an alternating magnetic field suggest that drug loaded EPS coated MNP could be used as effectual nanocomposite against cancer.

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Magnetic targeting with HER-2 Conjugated curcumin loaded SPIONs

The development of an effective natural drug against pancreatic cancer is considered as a challenge. In our study we developed PLGA based nanoparticle encapsulating highly effective natural antitumor agent and SPIONs. SPIONs based nanoformulation have become an outstanding tool for target specific delivery vehicles for battle against deadly cancer. Magnetic nanoparticle based HER2-CUR-SPION-PLGA nanoformulation displayed enhanced intracellular uptake as well anti-cancer effectiveness. The conjugation of HER2 on the surface of the nanoconjugate equipped the probability of co-delivery of curcumin and MNPs toward active targeting with an enhanced synergistic therapeutic index. The mode of delivery of therapeutic agent into cancer cells was evaluated by magnetic targeting that resulted in superior treatment modality. Our results propose the PLGA-CUR-SPION nanoformulation holds longer characteristics that can accelerate the therapeutic efficiency by destroying pancreatic cancer cells upon effective magnetic targeting.

Dual drug, double targeted PLGA-MNPs

The ultimate goal in cancer therapy is to formulate multifunctional NPs;

tailored to specifically target the cancer cells and sparing the normal healthy neighboring cells. With this aim, in the present study we formulated dual targeted double drug-loaded PLGA-MNPs, characterized and evaluated for efficacy and as targeted drug delivery systems. The formulated nanodrug carrier system offered to deliver drugs in combination, demonstrating dose-dependent and pH responsive cytotoxicity in MCF-7 and G1 cells. Also, for targeted delivery of therapeutic payload we functionalized the nanocarriers with dual targeting ligands. Our results clearly indicate that, curcumin along with 5-FU in PLGA NPs resulted in enhanced uptake, cellular accumulation, and greater cytotoxicity in cancer cells. Further the potential of MHT was studied in which the synergistic effect of MNPs and combination of drug was found to be highly effective to destroy cancer cells within very short period of time thus triggering enhanced apoptosis. We believe that these fascinating dual targeted dual drug loaded magnetic nanoformulation serve as potential nanoplatform for highly proficient diagnostic and therapeutic (theragnostic) applications.

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Aptamer conjugated PLGA-MNPs as theragnostics

We have developed a multifunctional NP conjugated with the AS1411 aptamer that targets nucleolin, the protein expressed abundantly on cancer cell membrane. The multifunctionality to the nanoconjugate was tailored by loading two potential therapeutic agents (Cur and Gem) and MNPs for exploiting cancer cells under external magnetic filed. Our Apt-Cur-Gem-PLGA-MNP successfully targeted pancreatic cancer cells and was monitored by fluorescence imparted by Cur. The ability of the MNPs to impart MHT and magnetic ablation and manipulation of pancreatic cell lines was observed. The synergistic action of Cur and Gem during MHT and magnetic ablation induced cell death was highly significant. This multifunctional pancreatic cancer-targeted imaging and treatment strategy using the AS1411 aptamer–tagged PLGA MNPs offers a versatile tool that can augment the diagnosis and therapy in cancer patients.

Hybrid MNPs (Au-MNPS) as theragnostic agents

This investigation reports the development of hybrid magnetic nanoparticles with gold. The nanoparticles was further incorporated into PLGA and efficiently tagged with three ligands. The therapeutic potential to the nanoconjugate was imparted by two potent chemotherapeutic agents (Cur and Gem). The HMNPs was used for combined chemo-, photo- and MHT therapy against pancreatic and breast cancer. The high drug loading capacity accompanied with pH-sensitive release of encapsulated drugs can be used to augment the effectiveness of targeted delivery of anti-cancer drugs. The presence of triple targeting ligands extensively boosted the uptake of the nano-conjugates by cancer cells. Curcumin and Gemcitabine exhibited excellent anti-proliferative effects on cancer cells. In addition to the cytotoxic effects of incorporated drugs, the exceptional photo-thermal ablation (attributed by Au part) and MHT (contributed by MNPs) enhanced the ablation of cancer cells with the advantage of triple targeting. The investigated tri-modal lethality attained with the hybrid MNP proved exceptionally proficient. All together, this ‘all in one’ nano-conjugate system is suggested as an ideal candidate for future multi-modal therapeutic strategies against cancer cells.

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As a final outcome the chapter endorses the prospects of the application of MNPs for simultaneous diagnostic and therapeutic (theragnostic) agents against cancer (schematically represented). All the above research findings suggest the successful development and application of biocompatible multifunctional MNPs for curbing cancer.

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