Designing Theranostic Agents Based on Pluronic Stabilized Gold Nanoaggregates Loaded with Methylene Blue for Multimodal Cell Imaging and Enhanced Photodynamic Therapy

At present, multifunctional noble metal-based nanocomposites are extensively investigated for their potential in performing cellular imaging, diagnostics, and therapy by integration of unique plasmonic properties with the spectroscopic expression and therapeutic activity of appropriate drug. In this work, we report the fabrication of 3-dimensional (3-D) close-packed nanoassemblies of gold nanoparticles by controlling the aggregation of individual nanoparticles in solution and subsequent stabilization of formed aggregates by Pluronic block copolymer (F127) coating. Besides conferring high stability, Pluronic mediates the loading of Methylene Blue (MB) molecules which exhibit interesting spectroscopic and photochemical properties to be employed as both optical label and photosensitizing drug. Indeed, here we demonstrate the pertinence of the fabricated nanoassemblies to provide optical imaging of murine colon carcinoma cells (C-26) via both Raman and fluorescence signals collected from MB molecules, specifically by using scanning confocal surface-enhanced resonant raman spectroscopy (SERRS) and fluorescence lifetime imaging microscopy (FLIM) techniques. The specific configuration of as fabricated nanoassemblies allows a small population of MB molecules to be located in very small areas between the aggregated nanoparticles (“hot spots”) to provide SERRS signal while the other population remains captured in Pluronic coating and preserves both its fluorescence signal and singlet-oxygen generation capability. Remarkably, we demonstrate an enhanced photodynamic therapeutic activity of MB-loaded gold nanoaggregates against murine colon carcinoma cells (C-26), as compared to the free photosensitizer. To our knowledge, this is the first report on plasmonic nanoplatforms conveying photosensitizing drug into cells to operate as optical label via both SER­(R)S and FLIM and to perform enhanced photodynamic therapy

Carboplatin-Loaded, Raman-Encoded, Chitosan-Coated Silver Nanotriangles as Multimodal Traceable Nanotherapeutic Delivery Systems and pH Reporters inside Human Ovarian Cancer Cells

Ovarian cancer is a common cause of cancer death in women and is associated with the highest mortality rates of all gynecological malignancies. Carboplatin (CBP) is the most used cytotoxic agent in the treatment of ovarian cancer. Herein, we design and assess a CBP nanotherapeutic delivery system which allows combinatorial functionalities of chemotherapy, pH sensing, and multimodal traceable properties inside live NIH:OVCAR-3 ovarian cancer cells. In our design, a pH-sensitive Raman reporter, 4-mercaptobenzoic acid (4MBA) is anchored onto the surface of chitosan-coated silver nanotriangles (chit-AgNTs) to generate a robust surface-enhanced Raman scattering (SERS) traceable system. To endow this nanoplatform with chemotherapeutic abilities, CBP is then loaded to 4MBA-labeled chit-AgNTs (4MBA-chit-AgNTs) core under alkaline conditions. The uptake and tracking potential of CBP-4MBA-chit-AgNTs at different <i>Z</i>-depths inside live ovarian cancer cells is evaluated by dark-field and differential interference contrast (DIC) microscopy. The ability of CBP-4MBA-chit-AgNTs to operate as near-infrared (NIR)-responsive contrast agents is validated using two noninvasive techniques: two-photon (TP)-excited fluorescence lifetime imaging microscopy (FLIM) and confocal Raman microscopy (CRM). The most informative data about the precise localization of nanocarriers inside cells correlated with intracellular pH sensing is provided by multivariate analysis of Raman spectra collected by scanning CRM. The <i>in vitro</i> cell proliferation assay clearly shows the effectiveness of the prepared nanocarriers in inhibiting the growth of NIH:OVCAR-3 cancer cells. We anticipate that this class of nanocarriers holds great promise for application in image-guided ovarian cancer chemotherapy