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Despite its common side effects and varying degrees of therapeutic success, chemotherapy remains the gold standard method for treatment of cancer. Towards developing a new therapeutic approach, we have engineered nanoparticles derived from erythrocytes that contain indocyanine green as a photo-activated agent that enables near infrared photothermal heating, and doxorubicin hydrochloride (DOX) as a chemotherapeutic drug. We hypothesize that milliseconds pulsed laser irradiation results in rapid heating and photo-triggered release of DOX, providing a dual photo-chemo therapeutic mechanism for tumor destruction. Additionally, the surface of the nanoparticles is functionalized with folate to target the folate receptor-α on tumor cells to further enhance the therapeutic efficacy. Using non-contract infrared radiometry and absorption spectroscopy, we have characterized the photothermal response and photostability of the nanoparticles to pulsed laser irradiation. Our in vitro studies show that these nanoparticles can mediate photo-chemo killing of SKOV3 ovarian cancer cells when activated by pulsed laser irradiation. We further demonstrate that this dual photo-chemo therapeutic approach is effective in reducing the volume of tumor implants in mice and elicits an apoptotic response. This treatment modality presents a promising approach in destruction of small tumor nodules.

Particle-based systems provide a capability for the delivery of imaging and/or therapeutic payloads. We have engineered constructs derived from erythrocytes, and doped with the FDA-approved near infrared dye, indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micron- to nano-scale. Herein, we investigated the effects of micron- (≈2.6 μm diameter), and nano- (≈145 nm diameter) sized NETs on their biodistribution, and evaluated their acute toxicity in healthy Swiss Webster mice. Following tail vein injection of free ICG and NETs, animals were euthanized at various time points up to 48 hours. Fluorescence analysis of blood showed that nearly 11% of the injected amount of nano-sized NETs (nNETs) remained in blood at 48 hours post-injection as compared to ≈5% for micron-sized NETs (μNETs). Similarly, at this time point, higher levels of nNETs were present in various organs including the lungs, liver, and spleen. Histological analyses of various organs, extracted at 24 hours post-injection of NETs, did not show pathological alterations. Serum biochemistry profiles, in general, did not show elevated levels of the various analyzed biomarkers associated with liver and kidney functions. Values of various hematological profiles remained within the normal ranges following the administration of μNETs and nNETs. Results of this study suggest that erythrocyte-derived particles can potentially provide a non-toxic platform for delivery of ICG.

Nanoparticles activated by near-infrared (NIR) excitation provide a capability for optical imaging and photodestruction of tumors. We have engineered optical nanoconstructs derived from erythrocytes, which are doped with the FDA-approved NIR dye, indocyanine green (ICG). We refer to these constructs as NIR erythrocyte-mimicking transducers (NETs). Herein, we investigate the phototheranostic capabilities of NETs for fluorescence imaging and photodestruction of SKBR3 breast cancer cells and subcutaneous xenograft tumors in mice. Our cellular studies demonstrate that NETs are internalized by these cancer cells and localized to their lysosomes. As evidenced by NIR fluorescence imaging and in vivo laser irradiation studies, NETs remain available within tumors at 24 h postintravenous injection. In response to continuous wave 808 nm laser irradiation at intensity of 680 mW/cm(2) for 10−15 min, NETs mediate the destruction of cancer cells and tumors in mice through synergistic photochemical and photothermal effects. We demonstrate that NETs are effective in mediating photoactivation of Caspase-3 to induce tumor apoptosis. Our results provide support for the effectiveness of NETs as theranostic agents for fluorescence imaging and photodestruction of tumors and their role in photoinduced apoptosis initiated by their localization to lysosomes.

Freezing of erythrocyte-derived nanoparticles can provide a method to extend their storage life and enable rapid deployment for clinical applications. We found that key physical properties of the particles remained unaffected after one freeze-thaw cycle.

We have engineered hybrid nanostructures derived from erythrocytes, which can be doped with various near infrared (NIR) organic chromophores, including the FDA-approved indocyanine green (ICG). We refer to these vesicles as NIR erythrocyte-mimicking transducers (NETs), as they are capable of generating heat, reactive oxygen species (ROS) or emit fluorescence light. We present preliminary results that demonstrate the effectiveness of NETs for fluorescence imaging and photodynamic therapeutic destruction of breast cancer cells, upon photo-excitation using NIR light. These hybrid nanostructures present a promising platform with theranostic capability for future biomedical clinical applications.

We have engineered nano-vesicles, derived from erythrocytes, which can be doped with various near infrared (NIR) organic chromophores, including the FDA-approved indocyanine green (ICG). We refer to these vesicles as NIR erythrocyte-mimicking transducers (NETS) since in response to NIR photo-excitation they can generate heat or emit fluorescent light. Using biochemical methods based on reduction amination, we have functionalized the surface of NET with antibodies to target specific biomolecules. We present results that demonstrate the effectiveness of NETs in targeted imaging of cancer cells that over-express the human epidermal growth factor receptor-2 (HER2).

Erythrocyte-based nanoparticle platforms can offer long circulation times not offered by traditional drug delivery methods. We have developed a novel erythrocyte-based nanoparticle doped with indocyanine green (ICG), the only FDA-approved near-infrared chromophore. Here, we report on the absorption and fluorescence emission characteristics of these nanoparticles fabricated using ICG concentrations in the range of 161-323 μM. These nanoparticles may serve as biocompatible optical materials for various clinical imaging and phototherapeutic applications.

Constructs derived from mammalian cells are emerging as a new generation of nano-scale platforms for clinical imaging applications. Herein, we report successful engineering of hybrid nano-structures composed of erythrocyte-derived membranes doped with FDA-approved near infrared (NIR) chromophore, indocyanine green (ICG), and surface-functionalized with antibodies to achieve molecular targeting. We demonstrate that these constructs can be used for targeted imaging of cancer cells in vitro. These erythrocyte-derived optical nano-probes may provide a potential platform for clinical translation, and enable molecular imaging of cancer biomarkers.