Lissett R. Bickford

A New Era for Cancer Treatment: Gold-Nanoparticle- Mediated Thermal Therapies

Nanotechnology-based cancer treatment approaches potentially provide localized, targeted therapies that aim to enhance efficacy, reduce side effects, and improve patient quality of life. Gold-nanoparticle-mediated hyperthermia shows particular promise in animal studies, and early clinical testing is currently underway. In this article, the rapidly evolving field of gold nanoparticle thermal therapy is reviewed, highlighting recent literature and describing current challenges to clinical translation of the technology.

Antibody-conjugated gold-gold sulfide nanoparticles as multifunctional agents for imaging and therapy of breast cancer

The goal of this study was to develop near-infrared (NIR) resonant gold-gold sulfide nanoparticles (GGS-NPs) as dual contrast and therapeutic agents for cancer management via multiphoton microscopy followed by higher intensity photoablation. We demonstrate that GGS-NPs exposed to a pulsed, NIR laser exhibit two-photon induced photoluminescence that can be utilized to visualize cancerous cells in vitro. When conjugated with anti-HER2 antibodies, these nanoparticles specifically bind SK-BR-3 breast carcinoma cells that over-express the HER2 receptor, enabling the cells to be imaged via multiphoton microscopy with an incident laser power of 1 mW. Higher excitation power (50 mW) could be employed to induce thermal damage to the cancerous cells, producing extensive membrane blebbing within seconds leading to cell death. GGS-NPs are ideal multifunctional agents for cancer management because they offer the ability to pinpoint precise treatment sites and perform subsequent thermal ablation in a single setting.

Immunoconjugated gold nanoshell-mediated photothermal ablation of trastuzumab-resistant breast cancer cells

Trastuzumab is a FDA-approved drug that has shown clinical efficacy against HER2+ breast cancers and is commonly used in combination with other chemotherapeutics. However, many patients are innately resistant to trastuzumab, or will develop resistance during treatment. Alternative treatments are needed for trastuzumab-resistant patients. Here, we investigate gold nanoparticle-mediated photothermal therapies as a potential alternative treatment for chemotherapy-resistant cancers. Gold nanoshell photothermal therapy destroys the tumor cells using heat, a physical mechanism, which is able to overcome the cellular adaptations that bestow trastuzumab resistance. By adding anti-HER2 to the gold surface of the nanoshells as a targeting modality, we increase the specificity of the nanoshells for HER2+ breast cancer. Silica–gold nanoshells conjugated with anti-HER2 were incubated with both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells. Nanoshell binding was confirmed using two-photon laser scanning microscopy, and the cells were then ablated using a near-infrared laser. We demonstrate the successful targeting and ablation of trastuzumab-resistant cells using anti-HER2-conjugated silica–gold nanoshells and a near-infrared laser. This study suggests potential for applying gold nanoshell-mediated therapy to trastuzumab-resistant breast cancers in vivo.

The stabilization and targeting of surfactant-synthesized gold nanorods

The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740,000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.

Rapidly–Dissolvable Microneedle Patches Via a Highly Scalable and Reproducible Soft Lithography Approach

Microneedle devices for transdermal drug delivery have recently become an attractive method to overcome the diffusion-limiting epidermis and effectively transport therapeutics to the body. Here, we demonstrate the fabrication of highly reproducible and completely dissolvable polymer microneedles on flexible water-soluble substrates. These biocompatible microneedles (made by using a soft lithography process known as PRINT) showed efficacy in piercing both murine and human skin samples and delivering a fluorescent drug surrogate to the tissue.

Silica-gold nanoshells as potential intraoperative molecular probes for HER2-overexpression in ex vivo breast tissue using near-infrared reflectance confocal microscopy.

Obtaining negative margins is critical for breast cancer patients undergoing conservation therapy in order to reduce the reemergence of the original cancer. Currently, breast cancer tumor margins are examined in a pathology lab either while the patient is anesthetized or after the surgical procedure has been terminated. These current methods often result in cancer cells present at the surgical resection margin due to inadequate margin assessment at the point of care. Due to such limitations evident in current diagnoses, tools for increasing the accuracy and speed of tumor margin detection directly in the operating room are still needed. We are exploring the potential of using a nano-biophotonics system to facilitate intraoperative tumor margin assessment ex vivo at the cellular level. By combining bioconjugated silica-based gold nanoshells, which scatter light in the near-infrared, with a portable FDA-approved reflectance confocal microscope, we first validate the use of gold nanoshells as effective reflectance-based imaging probes by evaluating the contrast enhancement of three different HER2-overexpressing cell lines. Additionally, we demonstrate the ability to detect HER2-overexpressing cells in human tissue sections within 5 min of incubation time. This work supports the use of targeted silica-based gold nanoshells as potential real-time molecular probes for HER2-overexpression in human tissue.

Local iontophoretic administration of cytotoxic therapies to solid tumors

Local administration of cytotoxic drugs using iontophoresis results in drug accumulation and therapeutic efficacy in mouse models of pancreatic and breast cancer and favorable PK in a large animal model. Electric field drives drugs into tumors Maintaining a high local concentration of anticancer drug may be key to killing tumors, but sometimes, therapeutics need an extra “push” to fully penetrate cancer tissues. Byrne and colleagues created a new implantable device that relies on iontophoresis—or, the flow of charged molecules in an electric field—to drive drugs into tumors. In doing so, the device, lodged in the tumor, enables local delivery of cytotoxic therapies. The authors tested their iontophoretic devices in mouse models of human pancreatic and breast cancers, using the standard drugs gemcitabine and cisplatin. The device enhanced the therapeutic efficacy of the drugs, slowing tumor growth in all animals and prolonging survival in the breast cancer models, especially when in combination with radiotherapy. In dogs, the device showed favorable pharmacokinetic profiles, indicating that, if implanted in humans, drugs would be retained primarily at the site of the tumor rather than traveling throughout the body, damaging healthy tissues. By maintaining high local drug concentrations and low systemic exposure, the iontophoretic device could improve long-term patient outcomes compared with intravenous injection of cytotoxic therapies. Currently, there are iontophoretic catheters (for bladder) and pumps (for arteries) being tested in patients, thus paving the way for this device to move into human solid tumors. Parenteral and oral routes have been the traditional methods of administering cytotoxic agents to cancer patients. Unfortunately, the maximum potential effect of these cytotoxic agents has been limited because of systemic toxicity and poor tumor perfusion. In an attempt to improve the efficacy of cytotoxic agents while mitigating their side effects, we have developed modalities for the localized iontophoretic delivery of cytotoxic agents. These iontophoretic devices were designed to be implanted proximal to the tumor with external control of power and drug flow. Three distinct orthotopic mouse models of cancer and a canine model were evaluated for device efficacy and toxicity. Orthotopic patient-derived pancreatic cancer xenografts treated biweekly with gemcitabine via the device for 7 weeks experienced a mean log2 fold change in tumor volume of –0.8 compared to a mean log2 fold change in tumor volume of 1.1 for intravenous (IV) gemcitabine, 3.0 for IV saline, and 2.6 for device saline groups. The weekly coadministration of systemic cisplatin therapy and transdermal device cisplatin therapy significantly increased tumor growth inhibition and doubled the survival in two aggressive orthotopic models of breast cancer. The addition of radiotherapy to this treatment further extended survival. Device delivery of gemcitabine in dogs resulted in more than 7-fold difference in local drug concentrations and 25-fold lower systemic drug levels than the IV treatment. Overall, these devices have potential paradigm shifting implications for the treatment of pancreatic, breast, and other solid tumors.

Rapid Stereomicroscopic Imaging of HER2 Overexpression in Ex Vivo Breast Tissue Using Topically Applied Silica-Based Gold Nanoshells

Tumor margin detection for patients undergoing breast conservation surgery primarily occurs postoperatively. Previously, we demonstrated that gold nanoshells rapidly enhance contrast of HER2 overexpression in ex vivo tissue sections. Our ultimate objective, however, is to discern HER2 overexpressing tissue from normal tissue in whole, nonsectioned, specimens to facilitate rapid diagnoses. Here, we use targeted nanoshells to quickly and effectively visualize HER2 receptor expression in intact ex vivo human breast tissue specimens. Punch biopsies of human breast tissue were analyzed after a brief 5-minute incubation with and without HER2-targeted silica-gold nanoshells using two-photon microscopy and stereomicroscopy. Labeling was subsequently verified using reflectance confocal microscopy, darkfield hyperspectral imaging, and immunohistochemistry to confirm levels of HER2 expression. Our results suggest that anti-HER2 nanoshells used in tandem with a near-infrared reflectance confocal microscope and a standard stereomicroscope may potentially be used to discern HER2-overexpressing cancerous tissue from normal tissue in near real time and offer a rapid supplement to current diagnostic techniques.

Cancer Imaging and Thermal Therapy Facilitated by Nanoparticles and Multiphoton Microscopy

Despite use of currently available technologies, cancer remains one of the leading causes of death worldwide. Gold-based nanoparticles that strongly absorb near-infrared light, such as nanoshells and nanorods, have shown potential as both diagnostic and therapeutic agents for cancer management (1–3). In this work we explored the use of gold-gold sulfide nanoparticles (mean diameter = 37 nm) with peak plasmon resonance at 800 nm for combined imaging and therapy of breast cancer. Upon excitation with a pulsed laser, these particles exhibit two-photon induced luminescence which may be used to image cancer cells. In addition, by increasing the power output of the laser, cancer cells can be thermally ablated as the gold-gold sulfide nanoparticles convert the light energy into heat.Copyright

PbS Quantum Dots for Near-Infrared Fluorescence Imaging

In this phantom-based study, we assessed the imaging potential of lead sulfide (PbS) near-infrared quantum dots (QDs) as novel contrast agents for deep tissue fluorescence imaging applications.