LED-activated methylene blue-loaded Pluronic-nanogold hybrids for in vitro photodynamic therapy

Optimization of Tyrosine Kinase Inhibitor-Loaded Gold Nanoparticles for Stimuli-Triggered Antileukemic Drug Release

Tyrosine kinase inhibitor (TKI) therapy is gaining attraction in advanced cancer therapeutics due to the ubiquity of kinases in cell survival and differentiation. Great progress was made in the past years in identifying tyrosine kinases that can function as valuable molecular targets and for the entrapment of their corresponding inhibitors in delivery compounds for triggered release. Herein we present a class of drug-delivery nanocompounds based on TKI Midostaurin-loaded gold nanoparticles that have the potential to be used as theranostic agents for the targeting of the FMS-like tyrosine kinase 3 (FLT3) in acute myeloid leukemia. We optimized the nanocompounds' formulation with loading efficiency in the 84-94% range and studied the drug release behavior in the presence of stimuli-responsive polymers. The therapeutic activity of MDS-loaded particles, superior to that of the free drug, was confirmed with toxicities depending on specific dosage ranges. No effect was observed on FLT3-negative cells or for the unloaded particles. Beyond druggability, we can track this type of nanocarrier inside biological structures as demonstrated via dark field microscopy. These properties might contribute to the facilitation of personalized drug dosage administration, critical for attaining a maximal therapeutic effect.

Investigation into the Photochemical Properties of Methylene Blue-Immobilized Hydroxyapatite Nanoparticles for Theranostic Application

In the biomedical field, there has been a requirement for developing theranostic nanomaterials with higher biosafety, leading to both diagnosis and therapy. Methylene blue (MB⁺) is an organic dye with both photoluminescence (PL) and photosensitization abilities to generate singlet oxygen (¹O₂). However, MB⁺ easily loses its generation ability by hydrogen reduction in vivo or by forming aggregates. In this study, MB⁺ immobilized on biocompatible hydroxyapatite (HA) nanoparticles was applied for the bifunctions of efficient PL and photosensitization. The MB⁺-immobilized HA nanoparticles (MH) formed aggregates with sizes of 80-100 nm in phosphate buffer (PB). The generation amount and efficiency of ¹O₂ from the nanoparticles in PB seem to depend on the immobilized MB⁺ amount and the percentage of the monomer, respectively. Considering the larger immobilized amount and percentage of the MB⁺ monomer, it was found that there was MH with the lower generation amount and efficiency of ¹O₂ to exhibit the highest PL intensity. The photofunctional measurement of MB⁺ revealed the state of MB⁺ molecules on the HA surface, and it was suggested that the MB⁺ molecules immobilized on the MH surface would form more hydrogen bonds to change their excitation states. In the cellular experiments, the Hela cancer cells reacted with the nanoparticles and showed red-color PL, indicating cellular imaging. Furthermore, the adherent cell coverage decreased by ¹O₂ generation, indicating the importance of the immobilization amount of the MB⁺ monomer. Therefore, theranostic nanomaterials with biosafety were successfully synthesized to show two photofunctions, which provide both cellular imaging and photodynamic therapy by the nanohybrid system between HA and MB⁺.

Effective Immobilization of Monomeric Methylene Blue on Hydroxyapatite Nanoparticles by Controlling Inorganic-Organic Interfacial Interactions

We successfully synthesized methylene blue (MB⁺)-immobilized hydroxyapatite (HM) nanoparticles by changing the initial P/Ca molar ratio. The immobilized amount of MB⁺ increased with increasing the initial P/Ca molar ratio from 0.6 to 4.0, and the HM had an elliptical shape (long length, 21-24 nm; short length, 11-13 nm) irrespective of the initial P/Ca molar ratio. Upon increasing the initial P/Ca molar ratio, the number of carbonate ions on the HM surface decreased, which would be owing to the electrostatic repulsion by the surface phosphate ions (i.e., P-O^-), the surface P-OH mainly dissociated to form P-O^-, and the electrostatic interaction of P-O^- with MB⁺ enhanced. The bonding of MB⁺ with surface P-OH and Ca²⁺ sites of hydroxyapatite would be hydrogen-bonding and Lewis acid-base interactions, respectively. The optimum synthesis condition for MB⁺ immobilization at the monomer state was found to be the initial P/Ca molar ratio of 2.0. Here, the existence percentage of the MB⁺ monomer and the molecular occupancy of the surface carbonate ion at the initial P/Ca molar ratio of 2.0 were higher than those at 4.0 with no significant difference in the immobilized amount of MB⁺, indicating that MB⁺ at the initial P/Ca molar ratio of 4.0 is more aggregated than that at 2.0. These results suggested that a part of carbonate ions has a role as a spacer to suppress MB⁺ aggregation. Accordingly, the interfacial interactions between the MB⁺ monomer and the hydroxyapatite surface were clarified, which can effectively be controlled by the initial P/Ca molar ratio. These findings will provide fundamental and useful knowledge for the design of calcium phosphate-organic nanohybrids. We believe that these particles will be the base materials to realize diagnostic and/or therapeutic functions through the molecular state control by optimizing the synthesis conditions.

A cationic [Ag12S12] cluster-based 2D coordination polymer and its dye composite with enhanced photocurrent and dielectric responses

A cationic cluster-based 2D coordination polymer captures Congo Red to form a composite with improved photocurrent and dielectric responses.

Aluminum plasmonic nanoshielding in ultraviolet inactivation of bacteria

Ultraviolet (UV) irradiation is an effective bacterial inactivation technique with broad applications in environmental disinfection. However, biomedical applications are limited due to the low selectivity, undesired inactivation of beneficial bacteria and damage of healthy tissue. New approaches are needed for the protection of biological cells from UV radiation for the development of controlled treatment and improved biosensors. Aluminum plasmonics offers attractive opportunities for the control of light-matter interactions in the UV range, which have not yet been explored in microbiology. Here, we investigate the effects of aluminum nanoparticles (Al NPs) prepared by sonication of aluminum foil on the UVC inactivation of E. coli bacteria and demonstrate a new radiation protection mechanism via plasmonic nanoshielding. We observe direct interaction of the bacterial cells with Al NPs and elucidate the nanoshielding mechanism via UV plasmonic resonance and nanotailing effects. Concentration and wavelength dependence studies reveal the role and range of control parameters for regulating the radiation dosage to achieve effective UVC protection. Our results provide a step towards developing improved radiation-based bacterial treatments.

Optimized Photodynamic Therapy with Multifunctional Cobalt Magnetic Nanoparticles

Photodynamic therapy (PDT) has been adopted as a minimally invasive approach for the localized treatment of superficial tumors, representing an improvement in the care of cancer patients. To improve the efficacy of PDT, it is important to first select an optimized nanocarrier and determine the influence of light parameters on the photosensitizing agent. In particular, much more knowledge concerning the importance of fluence and exposure time is required to gain a better understanding of the photodynamic efficacy. In the present study, we synthesized novel folic acid-(FA) and hematoporphyrin (HP)-conjugated multifunctional magnetic nanoparticles (CoFe₂O₄-HPs-FAs), which were characterized as effective anticancer reagents for PDT, and evaluated the influence of incubation time and light exposure time on the photodynamic anticancer activities of CoFe₂O₄-HPs-FAs in prostate cancer cells (PC-3 cells). The results indicated that the same fluence at different exposure times resulted in changes in the anticancer activities on PC-3 cells as well as in reactive oxygen species formation. In addition, an increase of the fluence showed an improvement for cell photo-inactivation. Therefore, we have established optimized conditions for new multifunctional magnetic nanoparticles with direct application for improving PDT for cancer patients.

Doxorubicin-Incorporated Nanotherapeutic Delivery System Based on Gelatin-Coated Gold Nanoparticles: Formulation, Drug Release, and Multimodal Imaging of Cellular Internalization

In this work, we developed a new pH- and temperature-responsive nanochemotherapeutic system based on Doxorubicin (DOX) noncovalently bound to biosynthesized gelatin-coated gold nanoparticles (DOX-AuNPs@gelatin). The real-time release profile of DOX was evaluated at different pH values (7.4, 5.3, and 4.6) and temperatures (22-45 °C) in aqueous solutions, and its therapeutic performance was examined in vitro against MCF-7 breast cancer cells. TEM, dark-field scattering, and wide-field fluorescence microscopy indicated the effective uptake of nanochemotherapeutics with the subsequent release and progressive accumulation of DOX in cell nuclei. MTT assays clearly showed the effectiveness of the treatment by inhibiting the growth of MCF-7 breast cancer cells for a loaded drug concentration of 5 μg/mL. The most informative data about the dynamic release and localization were provided by scanning confocal microscopy using time-resolved fluorescence and surface-enhanced Raman scattering (SERS) techniques. In particular, fluorescence-lifetime imaging (FLIM) recorded under 485 nm pulsed diode laser excitation revealed the bimodal distribution of DOX in cells. The shorter fluorescence lifetime of DOX localized in nuclei (1.52 ns) than in the cytoplasm (2.4 ns) is consistent with the cytotoxic mechanism induced by DOX-DNA intercalation. Remarkably, the few DOX molecules captured between nanoparticles ("electromagnetic hotspots") after most drug is released act as SERS reporters for the localization of plasmonic nanocarriers in MCF-7 cells. The high drug loading capacity and effective drug release under pH control combined with the advantage of multimodal visualization inside cells clearly indicate the high potential of our DOX-AuNPs@gelatin delivery system for implementation in nanomedicine.

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.

Nanopharmacology in translational hematology and oncology

Nanoparticles have displayed considerable promise for safely delivering therapeutic agents with miscellaneous therapeutic properties. Current progress in nanotechnology has put forward, in the last few years, several therapeutic strategies that could be integrated into clinical use by using constructs for molecular diagnosis, disease detection, cytostatic drug delivery, and nanoscale immunotherapy. In the hope of bringing the concept of nanopharmacology toward a viable and feasible clinical reality in a cancer center, the present report attempts to present the grounds for the use of cell-free nanoscale structures for molecular therapy in experimental hematology and oncology.

Nano-photosensitizers Engineered to Generate a Tunable Mix of Reactive Oxygen Species, for Optimizing Photodynamic Therapy, Using a Microfluidic Device

This work is aimed at engineering photosensitizer embedded nanoparticles (NPs) that produce optimal amount of reactive oxygen species (ROS) for photodynamic therapy (PDT). A revised synthetic approach, coupled with improved analytical tools, resulted in more efficient PDT. Specifically, methylene blue (MB) conjugated polyacrylamide nanoparticles (PAA NPs), with a polyethylene glycol dimethacrylate (PEGDMA, Mn 550) cross-linker, were synthesized so as to improve the efficacy of cancer PDT. The long cross-linker chain, PEGDMA, increases the distance between the conjugated MB molecules so as to avoid self-quenching of the excited states or species, and also enhances the oxygen permeability of the NP matrix, when compared to the previously used shorter cross-linker. The overall ROS production from the MB-PEGDMA PAA NPs was evaluated using the traditional way of monitoring the oxidation rate kinetics of anthracence-9,10-dipropionic acid (ADPA). We also applied singlet oxygen sensor green (SOSG) so as to selectively derive the singlet oxygen (1O2) production rate. This analysis enabled us to investigate the ROS composition mix based on varied MB loading. To effectively obtain the correlation between the ROS productivity and the cell killing efficacy, a microfluidic chip device was employed to provide homogeneous light illumination from an LED for rapid PDT efficacy tests, enabling simultaneous multiple measurements while using only small amounts of NPs sample. This provided multiplexed, comprehensive PDT efficacy assays, leading to the determination of a near optimal loading of MB in a PAA matrix for high PDT efficacy by measuring the light-dose-dependent cell killing effects of the various MB-PEGDMA PAA NPs using C6 glioma cancer cells.