Interrogating the Role of Endocytosis Pathway and Organelle Trafficking for Doxorubicin-Based Combination Ionic Nanomedicines.

We have studied the endocytic mechanisms that determine subcellular localization for three carrier-free chemotherapeutic-photothermal (chemo-PTT) combination ionic nanomedicines (INMs) composed of doxorubicin (DOX) and an near-infrared (NIR) dye (ICG, IR820, or IR783). This study aims to understand the cellular basis for previously published enhanced toxicity results of these combination nanomedicines toward MCF-7 breast cancer cells. The active transport mechanism of INMs, unlike free DOX, which is known to employ passive transport, was validated by conducting temperature-dependent cellular uptake of the drug in MCF-7 cells using confocal microscopy. The internalization pathway of these INMs was further probed in the presence and absence of different endocytosis inhibitors. Detailed examination of the mode of entry of the carrier-free INMs in MCF-7 cells revealed that they are primarily internalized through clathrin-mediated endocytosis. In addition, time-dependent subcellular localization studies were also investigated. Examination of time-dependent confocal images indicated that the INMs targeted multiple organelles, in contrast to free DOX that primarily targets the nucleus. Collectively, the high cellular endocytic uptake in cancerous cells (EPR effect) and the multimode targeting ability demonstrated the main reason for the low half-maxima inhibitory concentration (IC50) value (the high cytotoxicity) of these carrier-free INMs as compared to their respective parent chemo and PTT drugs.

Doxorubicin-Based Ionic Nanomedicines for Combined Chemo-Phototherapy of Cancer.

Synergistic combination therapy approach offers lots of options for delivery of materials with anticancer properties, which is a very promising strategy to treat a variety of malignant lesions with enhanced therapeutic efficacy. The current study involves a detailed investigation of combination ionic nanomedicines where a chemotherapeutic drug is coupled with a photothermal agent to attain dual mechanisms (chemotherapy (chemo) and photothermal therapy (PTT)) to improve the drug's efficacy. An FDA-approved Doxorubicin hydrochloride (DOX·HCl) is electrostatically attached with a near-infrared cyanine dye (ICG, IR783, and IR820), which serves as a PTT drug using ionic liquid chemistry to develop three ionic material (IM)-based chemo-PTT drugs. Carrier-free ionic nanomedicines (INMs) are derived from ionic materials (IMs). The photophysical properties of the developed combination IMs and their INMs were studied in depth. The phototherapeutic efficiency of the combination drugs was evaluated by measuring the photothermal conversion efficiency and singlet-oxygen quantum yield. The improved photophysical properties of the combination nanomedicines in comparison to their parent compounds significantly enhanced INMs' photothermal efficiency. Cellular uptake, dark and light toxicity studies, and cell death mechanisms of the chemo-PTT nanoparticles were also studied in vitro. The combination INMs exhibited enhanced cytotoxicity compared to their respective parent compounds. Moreover, the apoptosis cell death mechanism was almost doubled for combination nanomedicine than the free DOX, which is attributed to enhanced cellular uptake. Examination of the combination index and improved in vitro cytotoxicity results revealed a great synergy between chemo and PTT drugs in the developed combination nanomedicines.

FRET-based carbazole-fluorescein ionic nanoparticle for use as an effective bioimaging agent.

FÓ§rster resonance energy transfer (FRET)-based systems are widely applicable in many areas of interest. In this study, a novel FRET-based ionic material (IM) was synthesized by pairing carbazole imidazolium cation (CI+) with fluorescein anion (Fl2-) through a simple ion-exchange method. The resulting IM ([CI]2[Fl]) was converted into an ionic nanoparticle (INP) in aqueous media for practical use for bioimaging application. The photophysical properties of the parent dyes, [CI]2[Fl], and INP were studied in detail. All FRET parameters were calculated in the synthesized material. [CI]2[Fl] exhibited a significant spectral overlap integral and an ideal theoretical FRET distance. The presence of the FRET mechanism was verified by the observed decrease in donor fluorescence lifetime and a moderate FRET efficiency in [CI]2[Fl]. The INP formed from [CI]2[Fl] was evaluated for use as a fluorescent pH probe and bioimaging agent. FRET efficiency of INP is calculated in a series of pH studies which indicates the highest efficiency at physiological pH. Whereas no FRET phenomenon is observed in highly acidic and basic conditions. The pH-dependent photophysical properties of [CI]2[Fl] are monitored and allow for the potential application as a fluorescent probe for the detection of acidic tissues in biological systems. The FRET-capable INP showed superior bioimaging capability in vitro as compared to the parent dye.

Antibiotics Coupled with Photothermal Therapy for the Enhanced Killing of Bacteria.

In this study, the application of ionic materials as a combination antibiotic drug was investigated. The fluoroquinolone, Norfloxacin, was converted into the ionic form and combined with the cationic dye, IR780+, using an ion-exchange reaction. The resulting ionic combination drug possesses two killing mechanisms in one compound. The antibiotic chemical mechanism along with the photothermal mechanism that was acquired by adding IR780 to the compound led to the development of a combination antibiotic drug. This ionic combination drug consisting of Norfloxacin anion and IR780 cation is easily dispersed in water using sonication waves. The parent compounds and ionic combination drug, dissolved in organic solvent and dispersed in water, were characterized, and the photophysical properties were studied in detail. It was discovered that the aqueous ionic combination drugs exhibited significant changes in absorbance and photoluminescent properties. In aqueous media, the dispersed ionic combination drug exhibited a very broad absorbance with an additional peak around 1000 nm which is advantageous in photothermal. A significant decrease in the quantum yield along with enhanced non-radiative rate constant was observed for the combination drug in the aqueous. The photothermal mechanism is present in both the parent IR780 dye and the ionic combination drug. The ionic combination drug displayed a high light-to-heat conversion efficiency and temperature increase similar to the parent dye. The combination of both killing mechanisms in the ionic combination drug resulted in enhanced antibacterial activity against Escherichia coli as compared to the parent Norfloxacin and IR780-I individually.