Blood Interactions, Pharmacokinetics, and Depth-Dependent Ablation of Rat Mammary Tumors with Photoactivatable, Liposomal Doxorubicin

Photosensitizers can be integrated with drug delivery vehicles to develop chemophototherapy agents with antitumor synergy between chemo- and photocomponents. Long-circulating doxorubicin (Dox) in porphyrin-phospholipid (PoP) liposomes (LC-Dox-PoP) incorporates a phospholipid-like photosensitizer (2 mole %) in the bilayer of Dox-loaded stealth liposomes. Hematological effects of endotoxin-minimized LC-Dox-PoP were characterized via standardized assays. In vitro interaction with erythrocytes, platelets, and plasma coagulation cascade were generally unremarkable, whereas complement activation was found to be similar to that of commercial Doxil. Blood partitioning suggested that both the Dox and PoP components of LC-Dox-PoP were stably entrapped or incorporated in liposomes. This was further confirmed with pharmacokinetic studies in Fischer rats, which showed the PoP and Dox components of the liposomes both had nearly identical, long circulation half-lives (25-26 hours). In a large orthotopic mammary tumor model in Fischer rats, following intravenous dosing (2 mg/kg Dox), the depth of enhanced Dox delivery in response to 665 nm laser irradiation was over 1 cm. LC-Dox-PoP with laser treatment cured or potently suppressed tumor growth, with greater efficacy observed in tumors 0.8 to 1.2 cm, compared with larger ones. The skin at the treatment site healed within approximately 30 days. Taken together, these data provide insight into nanocharacterization and photo-ablation parameters for a chemophototherapy agent.

Surfactant-Stripped Pheophytin Micelles for Multimodal Tumor Imaging and Photodynamic Therapy

Porphyrin-based nanomaterials can inherently integrate multiple contrast imaging functionalities with phototherapeutic capabilities. We dispersed pheophytin (Pheo) into Pluronic F127 and carried out low-temperature surfactant-stripping to remove the bulk surfactant. Surfactant-stripped Pheo (ss-Pheo) micelles exhibited a similar size, but higher near-infrared fluorescence, compared to two other nanomaterials also with high porphyrin density (surfactant-stripped chlorophyll micelles and porphysomes). Singlet oxygen generation, which was higher for ss-Pheo, enabled photodynamic therapy (PDT). ss-Pheo provided contrast for photoacoustic and fluorescence imaging, and following seamless labeling with ⁶⁴Cu, was used for positron emission tomography. ss-Pheo had a long blood circulation and favorable accumulation in an orthotopic murine mammary tumor model. Trimodal tumor imaging was demonstrated, and PDT resulted in delayed tumor growth.

A malaria vaccine adjuvant based on recombinant antigen binding to liposomes

Pfs25 is a malaria transmission-blocking vaccine antigen candidate, but its apparently limited immunogenicity in humans has hindered clinical development. Here, we show that recombinant, polyhistidine-tagged (his-tagged) Pfs25 can be mixed at the time of immunization with pre-formed liposomes containing cobalt porphyrin-phospholipid, resulting in spontaneous nanoliposome antigen particleization (SNAP). Antigens are stably presented in uniformly orientated display via his-tag insertion in the cobalt porphyrin-phospholipid bilayer, without covalent modification or disruption of antigen conformation. SNAP immunization of mice and rabbits is well tolerated with minimal local reactogenicity, and results in orders-of-magnitude higher functional antibody generation compared with other 'mix-and-inject' adjuvants. Serum-stable antigen binding during transit to draining lymph nodes leads to enhanced antigen uptake by phagocytic antigen-presenting cells, with subsequent generation of long-lived, antigen-specific plasma cells. Seamless multiplexing with four additional his-tagged Plasmodium falciparum polypeptides induces strong and balanced antibody production, illustrating the simplicity of developing multistage particulate vaccines with SNAP immunization.

Binding of an amphiphilic phthalocyanine to pre-formed liposomes confers light-triggered cargo release

Liposomes are able to load a range of cargos and have been used for drug delivery applications, including for stimuli-triggered drug release. Here, we describe an approach for imparting near infrared (NIR) light-triggered release to pre-formed liposomes, using a newly-synthesized cationic, amphiphilic phthalocyanine. When simply mixed in aqueous solution with cargo-loaded liposomes, the cationic amphiphilic phthalocyanine, but not a cationic hydrophilic azaphthalocyanine, spontaneously incorporates into the liposome bilayer. This enables subsequent release of loaded cargo (doxorubcin or basic orange) upon irradiation with NIR light. The rate of release could be altered by varying the amount of photosensitizer added to the liposomes. In the absence of NIR light exposure, stable cargo loading of the liposomes was maintained. Introduction.

Loading and Releasing Ciprofloxacin in Photoactivatable Liposomes

We demonstrate that ciprofloxacin can be actively loaded into liposomes that contain small amounts of porphyrin-phospholipid (PoP). PoP renders the liposomes photoactivatable, so that the antibiotic is released from the carrier under red light irradiation (665 nm). The use of 2 molar % PoP in the liposomes accommodated active loading of ciprofloxacin. Further inclusion of 2 molar % of an unsaturated phospholipid accelerated light-triggered drug release, with more than 90 % antibiotic release from the liposomes occurring in less than 30 seconds. With or without laser treatment, ciprofloxacin PoP liposomes inhibited the growth of Bacillus subtilis in liquid media, apparently due to uptake of the liposomes by the bacteria. However, when liposomes were first separated from smaller molecules with centrifugal filtration, only the filtrate from laser-treated liposomes was bactericidal, confirming effective release of active antibiotic. These results establish the feasibility of remote loading antibiotics into photoactivatable liposomes, which could lead to opportunities for enhanced localized antibiotic therapy.

Ingestible roasted barley for contrast-enhanced photoacoustic imaging in animal and human subjects

Photoacoustic computed tomography (PACT) is an emerging imaging modality. While many contrast agents have been developed for PACT, these typically cannot immediately be used in humans due to the lengthy regulatory process. We screened two hundred types of ingestible foodstuff samples for photoacoustic contrast with 1064 nm pulse laser excitation, and identified roasted barley as a promising candidate. Twenty brands of roasted barley were further screened to identify the one with the strongest contrast, presumably based on complex chemical modifications incurred during the roasting process. Individual roasted barley particles could be detected through 3.5 cm of chicken-breast tissue and through the whole hand of healthy human volunteers. With PACT, but not ultrasound imaging, a single grain of roasted barley was detected in a field of hundreds of non-roasted particles. Upon oral administration, roasted barley enabled imaging of the gut and peristalsis in mice. Prepared roasted barley tea could be detected through 2.5 cm chicken breast tissue. When barley tea was administered to humans, photoacoustic imaging visualized swallowing dynamics in healthy volunteers. Thus, roasted barley represents an edible foodstuff that should be considered for photoacoustic contrast imaging of swallowing and gut processes, with immediate potential for clinical translation.

A Tumor Vascular-Targeted Interlocking Trimodal Nanosystem That Induces and Exploits Hypoxia

Vascular-targeted photodynamic therapy (VTP) is a recently approved strategy for treating solid tumors. However, the exacerbated hypoxic stress makes tumor eradication challenging with such a single modality approach. Here, a new graphene oxide (GO)-based nanosystem for rationally designed, interlocking trimodal cancer therapy that enables VTP using photosensitizer verteporfin (VP) (1) with codelivery of banoxantrone dihydrochloride (AQ4N) (2), a hypoxia-activated prodrug (HAP), and HIF-1α siRNA (siHIF-1α) (3) is reported. The VTP-induced aggravated hypoxia is highly favorable for AQ4N activation into AQ4 (a topoisomerase II inhibitor) for chemotherapy. However, the hypoxia-induced HIF-1α acts as a "hidden brake," through downregulating CYP450 (the dominant HAP-activating reductases), to substantially hinder AQ4N activation. siHIF-1α is rationally adopted to suppress the HIF-1α expression upon hypoxia and further enhance AQ4N activation. This trimodal nanosystem significantly delays the growth of PC-3 tumors in vivo compared to the control nanoparticles carrying VP, AQ4N, or siHIF-1α alone or their pairwise combinations. This multimodal nanoparticle design presents, the first example exploiting VTP to actively induce hypoxia for enhanced HAP activation. It is also revealed that HAP activation is still insufficient under hypoxia due to the hidden downregulation of the HAP-activating reductases (CYP450), and this can be well overcome by GO nanoparticle-mediated siHIF-1α intervention.

Recent Progress in Upconversion Photodynamic Therapy

Photodynamic therapy (PDT) is a minimally invasive cancer modality that combines a photosensitizer (PS), light, and oxygen. Introduction of new nanotechnologies holds potential to improve PDT performance. Upconversion nanoparticles (UCNPs) offer potentially advantageous benefits for PDT, attributed to their distinct photon upconverting feature. The ability to convert near-infrared (NIR) light into visible or even ultraviolet light via UCNPs allows for the activation of nearby PS agents to produce singlet oxygen, as most PS agents absorb visible and ultraviolet light. The use of a longer NIR wavelength permits light to penetrate deeper into tissue, and thus PDT of a deeper tissue can be effectively achieved with the incorporation of UCNPs. Recent progress in UCNP development has generated the possibility to employ a wide variety of NIR excitation sources in PDT. Use of UCNPs enables concurrent strategies for loading, targeting, and controlling the release of additional drugs. In this review article, recent progress in the development of UCNPs for PDT applications is summarized.

Naphthalocyanines as contrast agents for photoacoustic and multimodal imaging

Naphthalocyanines (Ncs) are a family of aromatic small molecule with large near infrared extinction coefficients, making them appealing contrast agent candidates for photoacoustic imaging (PAI). Depending on the substitutions on the Nc periphery or metal center, different spectrally-resolved absorption peak wavelengths are possible, which can enable photoacoustic contrast multiplexing. Owing to their generally poor aqueous solubility, approaches have been developed to modify Ncs or formulate them as biocompatible contrast agents for PAI. Due to their inherent capacity for metal ion chelation, Ncs hold potential for complementary multimodal contrast imaging techniques such as 64Cu positron emission tomography. In this research perspective, we highlight some recent reports involving the use of Ncs in PAI.

Tumor Ablation and Therapeutic Immunity Induction by an Injectable Peptide Hydrogel

Immunosuppressive tumor microenvironments (TMEs) create tremendous obstacles for an effective cancer therapy. Herein, we developed a melittin-RADA₃₂ hybrid peptide hydrogel loaded with doxorubicin (DOX) for a potent chemoimmunotherapy against melanoma through the active regulation of TMEs. The formed melittin-RADA₃₂-DOX (MRD) hydrogel has an interweaving nanofiber structure and exhibits excellent biocompatibility, controlled drug release properties both in vitro and in vivo, and an enhanced killing effect to melanoma cells. A single-dose injection of MRD hydrogel retarded the growth of primary melanoma tumors by more than 95% due to loaded melittin and DOX, with concomitant recruitment of activated natural killer cells in the tumors. Furthermore, MRD hydrogel can activate dendritic cells of draining lymph nodes, specifically deplete M2-like tumor-associated macrophages (TAMs), and produce active, cytotoxic T cells to further defend the cells against remaining tumors, providing potent anticancer efficacy against subcutaneous and metastatic tumors in vivo. Multidose injection of MRD hydrogel eliminated 50% of the primary tumors and provided a strong immunological memory effect against tumor rechallenge after eradication of the initial tumors. Owing to its abilities to perform controlled drug release, regulate innate immune cells, deplete M2-like TAMs, direct anticancer and immune-stimulating capabilities, and reshape immunosuppressive TMEs, MRD hydrogel may serve as a powerful tool for anticancer applications.

Assessing Photosensitizer Targeting Using Meso-Tetra(Carboxyphenyl) Porphyrin

Mesotetra(4-carboxyphenyl)porphyrin (mTCPP) is a commercially available small molecule fluorophore and photosensitizer with four free carboxylic acid groups. mTCPP can readily be conjugated with amines for facile attachment of functional groups. In this work, we synthesized and assessed tetravalent, lysine-conjugated mTCPP, for its potential applications in targeted imaging and photodynamic therapy. Fmoc-protected d-lysine or l-lysine was conjugated to mTCPP via amide coupling with the epsilon amine group of lysine, followed by Fmoc deprotection. The resulting compounds did not dissolve well in aqueous solvent, but could be solubilized with the assistance of surfactants, including cholic acid. The l-amino acid transporter (LAT1) can uptake diverse neutral l-amino acids. In vitro studies with U87 cells revealed a non-specific uptake of the hydrophobic Fmoc-protected lysine-conjugated mTCPP precursors, but not d- or l-lysine mTCPP. Likewise, only the Fmoc-protected compounds induced substantial phototoxicty in cells following incubation and irradiation with blue light. These experimental results do not provide evidence to suggest that lysine-mTCPP is able to specifically target cancer cells. However, they do highlight mTCPP as a convenient and accessible framework for assessing molecular targeting of photosensitizers.

Short Drug-Light Intervals Improve Liposomal Chemophototherapy in Mice Bearing MIA PaCa-2 Xenografts

Chemophototherapy (CPT) is an emerging tumor treatment that combines phototherapy and chemotherapy. Long-circulating (LC) liposomes can stably incorporate 2 mol % porphyrin-phospholipid (PoP) in the bilayer and load doxorubicin (Dox) to generate LC-Dox-PoP liposomes, for single-agent CPT. Following intravenous administration to mice, LC-Dox-PoP liposomes (2 mg/kg Dox) circulated with similar blood concentration ranges produced by a typical human clinical dose of DOXIL (50 mg/m² Dox). This dosing approach aims to achieve physiologically relevant Dox and PoP concentrations as well as CPT vascular responses in mice bearing subcutaneous human pancreatic MIA PaCa-2 xenografts. Phototreatment with 2 mg/kg LC-Dox-PoP induced vascular permeabilization, leading to a 12.5-fold increase in Dox tumor influx estimated by a pharmacokinetic model, based on experimental data. Shorter drug-light intervals (0.5-3 h) led to greater tumoral drug deposition and improved treatment outcomes, compared to longer drug-light intervals. At 2 mg/kg Dox, CPT with LC-Dox-PoP liposomes induced tumor regression and growth inhibition, whereas chemotherapy using several other formulations of Dox did not. LC-Dox-PoP liposomes were well tolerated at the 2 mg/kg dose.

Multicolor Liposome Mixtures for Selective and Selectable Cargo Release

Many approaches exist for stimuli-triggered cargo release from nanocarriers, but few can provide for on-demand release of multiple payloads, selectively. Here, we report the synthesis of purpurin-phospholipid (Pur-P), a lipid chromophore that has near-infrared absorbance red-shifted by 30 nm compared to a structurally similar pyropheophorbide-phospholipid (Pyr-P). Liposomes containing small amounts of either Pur-P or Pyr-P exhibited similar physical properties and fluorescence self-quenching. Loaded with distinct cargos, Pur-P and Pyr-P liposomes were mixed into a single colloidal suspension and selectively released cargo depending on irradiation wavelength. Spatiotemporal control of distinct cargo release was achieved by controlling multicolor laser placement. Using basic orange and doxorubicin anthraquinones, multidimensional cytotoxicity gradients were established to gauge efficacy against cancer cells using light-released drug. Wavelength selectivity of cargo release was maintained following intramuscular administration to mice.

Intrabilayer 64Cu Labeling of Photoactivatable, Doxorubicin-Loaded Stealth Liposomes

Doxorubicin (Dox)-loaded stealth liposomes (similar to those in clinical use) can incorporate small amounts of porphyrin-phospholipid (PoP) to enable chemophototherapy (CPT). PoP is also an intrinsic and intrabilayer ⁶⁴Cu chelator, although how radiolabeling impacts drug delivery has not yet been assessed. Here, we show that ⁶⁴Cu can radiolabel the stable bilayer of preformed Dox-loaded PoP liposomes with inclusion of 1% ethanol without inducing drug leakage. Dox-PoP liposomes labeled with intrabilayer copper behaved nearly identically to unlabeled ones in vitro and in vivo with respect to physical parameters, pharmacokinetics, and CPT efficacy. Positron emission tomography and near-infrared fluorescence imaging visualized orthotopic mammary tumors in mice with passive liposome accumulation following administration. A single CPT treatment with 665 nm light (200 J/cm²) strongly inhibited primary tumor growth. Liposomes accumulated in lung metastases, based on NIR imaging. These results establish the feasibility of CPT interventions guided by intrinsic multimodal imaging of Dox-loaded stealth PoP liposomes.

Multifunctional Liposomes for Image-Guided Intratumoral Chemo-Phototherapy

Intratumoral (IT) drug injections reduce systemic toxicity, but delivered volumes and distribution can be inconsistent. To improve IT delivery paradigms, porphyrin-phospholipid (PoP) liposomes are passively loaded with three hydrophilic cargos: sulforhodamine B, a fluorophore; gadolinium-gadopentetic acid, a magnetic resonance (MR) agent; and oxaliplatin, a colorectal cancer chemotherapeutic. Liposome composition is optimized so that cargo is retained in serum and storage, but is released in less than 1 min with exposure to near infrared light. Light-triggered release occurs with PoP-induced photooxidation of unsaturated lipids and all cargos release concurrently. In subcutaneous murine colorectal tumors, drainage of released cargo is delayed when laser treatment occurs 24 h after IT injection, at doses orders of magnitude lower than systemic ones. Delayed light-triggering results in substantial tumor shrinkage relative to controls a week following treatment, although regrowth occurs subsequently. MR imaging reveals that over this time frame, pools of liposomes within the tumor migrate to adjacent regions, possibly leading to altered spatial distribution during triggered drug release. Although further characterization of cargo loading and release is required, this proof-of-principle study suggests that multimodal theranostic IT delivery approaches hold potential to both guide injections and interpret outcomes, in particular when combined with chemo-phototherapy.

Vessel-Targeted Chemophototherapy with Cationic Porphyrin-Phospholipid Liposomes

Cationic liposomes have been used for targeted drug delivery to tumor blood vessels, via mechanisms that are not fully elucidated. Doxorubicin (Dox)-loaded liposomes were prepared that incorporate a cationic lipid; 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), along with a small amount of porphyrin-phospholipid (PoP). Near-infrared (NIR) light caused release of entrapped Dox via PoP-mediated DOTAP photo-oxidation. The formulation was optimized to enable extremely rapid NIR light-triggered Dox release (i.e., in 15 seconds), while retaining reasonable serum stability. In vitro, cationic PoP liposomes readily bound to both MIA PaCa-2 human pancreatic cancer cells and human vascular endothelial cells. When administered intravenously, cationic PoP liposomes were cleared from circulation within minutes, with most accumulation in the liver and spleen. Fluorescence imaging revealed that some cationic PoP liposomes also localized at the tumor blood vessels. Compared with analogous neutral liposomes, strong tumor photoablation was induced with a single treatment of cationic PoP liposomes and laser irradiation (5 mg/kg Dox and 100 J/cm² NIR light). Unexpectedly, empty cationic PoP liposomes (lacking Dox) induced equally potent antitumor phototherapeutic effects as the drug loaded ones. A more balanced chemo- and phototherapeutic response was subsequently achieved when antitumor studies were repeated using higher drug dosing (7 mg/kg Dox) and a low fluence phototreatment (20 J/cm² NIR light). These results demonstrate the feasibility of vessel-targeted chemophototherapy using cationic PoP liposomes and also illustrate synergistic considerations. Mol Cancer Ther; 16(11); 2452-61. ©2017 AACR.

Surfactant-stripped naphthalocyanines for multimodal tumor theranostics with upconversion guidance cream

Surfactant-stripped, nanoformulated naphthalocyanines (nanonaps) can be formed with Pluronic F127 and low temperature membrane processing, resulting in dispersed frozen micelles with extreme contrast in the near infrared region. Here, we demonstrate that nanonaps can be used for multifunctional cancer theranostics. This includes lymphatic mapping and whole tumor photoacoustic imaging following intradermal or intravenous injection in rodents. Without further modification, pre-formed nanonaps were used for positron emission tomography and passively accumulated in subcutaneous murine tumors. Because the nanonaps used absorb light beyond the visible range, a topical upconversion skin cream was developed for anti-tumor photothermal therapy with laser placement that can be guided by the naked eye.

Implantable Tin Porphyrin-PEG Hydrogels with pH-Responsive Fluorescence

Tetracarboxy porphyrins can be polymerized with polyethylene glycol (PEG) diamines to generate hydrogels with intense, near-infrared, and transdermal fluorescence following subcutaneous implantation. Here, we show that the high density porphyrins of the preformed polymer can be chelated with tin via simple incubation. Tin porphyrin hydrogels exhibited increasing emission intensities, ratios, and lifetimes from pH 1 to 10. Tin porphyrin hydrogel emission was strongly reversible and pH responsiveness was observed in the physiological range between pH 6 and pH 8. pH-sensitive emission was detected via noninvasive transdermal fluorescence imaging in vivo following subcutaneous implantation in mice.

Bimodal Targeting Using Sulfonated, Mannosylated PEI for Combined Gene Delivery and Photodynamic Therapy

Photodynamic therapy (PDT) and gene delivery have both been used to target both cancer cells and tumor-associated macrophages (TAMs). Given the complex nature of tumor tissue, there could be merit in combining these strategies simultaneously. In this study, we developed a bimodal targeting approach to both cancer cells and macrophages, employing materials conducive to both gene delivery and PDT. Polymers libraries were created that consisted of cationic polyethyleneimine (PEI) conjugated to the photosensitizer pyropheophorbide-a, with sulfonation (to target selectin-expressing cells) and mannosylation (to target TAMs). Polyplexes, consisting of these polymers electrostatically bound to DNA, were analyzed for transfection efficacy and cytotoxicity toward epithelial cells and macrophages to assess dual-targeting. This study provides preliminary proof of principle for using modified PEI for targeted gene delivery and PDT.

Advanced Functional Nanomaterials for Theranostics

Nanoscale materials have been explored extensively as agents for therapeutic and diagnostic (i.e. theranostic) applications. Research efforts have shifted from exploring new materials in vitro to designing materials that function in more relevant animal disease models, thereby increasing potential for clinical translation. Current interests include non-invasive imaging of diseases, biomarkers and targeted delivery of therapeutic drugs. Here, we discuss some general design considerations of advanced theranostic materials and challenges of their use, from both diagnostic and therapeutic perspectives. Common classes of nanoscale biomaterials, including magnetic nanoparticles, quantum dots, upconversion nanoparticles, mesoporous silica nanoparticles, carbon-based nanoparticles and organic dye-based nanoparticles, have demonstrated potential for both diagnosis and therapy. Variations such as size control and surface modifications can modulate biocompatibility and interactions with target tissues. The needs for improved disease detection and enhanced chemotherapeutic treatments, together with realistic considerations for clinically translatable nanomaterials will be key driving factors for theranostic agent research in the near future.

Chemophototherapy: An Emerging Treatment Option for Solid Tumors

Near infrared (NIR) light penetrates human tissues with limited depth, thereby providing a method to safely deliver non-ionizing radiation to well-defined target tissue volumes. Light-based therapies including photodynamic therapy (PDT) and laser-induced thermal therapy have been validated clinically for curative and palliative treatment of solid tumors. However, these monotherapies can suffer from incomplete tumor killing and have not displaced existing ablative modalities. The combination of phototherapy and chemotherapy (chemophototherapy, CPT), when carefully planned, has been shown to be an effective tumor treatment option preclinically and clinically. Chemotherapy can enhance the efficacy of PDT by targeting surviving cancer cells or by inhibiting regrowth of damaged tumor blood vessels. Alternatively, PDT-mediated vascular permeabilization has been shown to enhance the deposition of nanoparticulate drugs into tumors for enhanced accumulation and efficacy. Integrated nanoparticles have been reported that combine photosensitizers and drugs into a single agent. More recently, light-activated nanoparticles have been developed that release their payload in response to light irradiation to achieve improved drug bioavailability with superior efficacy. CPT can potently eradicate tumors with precise spatial control, and further clinical testing is warranted.

Deep tissue photoacoustic computed tomography with a fast and compact laser system

Photoacoustic computed tomography (PACT) holds great promise for biomedical imaging, but wide-spread implementation is impeded by the bulkiness of flash-lamp-pumped laser systems, which typically weigh between 50 - 200 kg, require continuous water cooling, and operate at a low repetition rate. Here, we demonstrate that compact lasers based on emerging diode technologies are well-suited for preclinical and clinical PACT. The diode-pumped laser used in this study had a miniature footprint (13 × 14 × 7 cm³), weighed only 1.6 kg, and outputted up to 80 mJ per pulse at 1064 nm. In vitro, the laser system readily provided over 4 cm PACT depth in chicken breast tissue. In vivo, in addition to high resolution, non-invasive brain imaging in living mice, the system can operate at 50 Hz, which enabled high-speed cross-sectional imaging of murine cardiac and respiratory function. The system also provided high quality, high-frame rate, and non-invasive three-dimensional mapping of arm, palm, and breast vasculature at multi centimeter depths in living human subjects, demonstrating the clinical viability of compact lasers for PACT.

Design of Hydrated Porphyrin-Phospholipid Bilayers with Enhanced Magnetic Resonance Contrast

Computer simulations are used to design more hydrated bilayers, formed from amine-modified porphyrin-phospholipids (PoPs). Experiments confirm that the new constructs give rise to bilayers with greater water content. When chelated with manganese, amine-modified PoPs provide improved contrast for magnetic resonance and are safely used for imaging in vivo.

Targeted Nanomaterials for Phototherapy

Phototherapies involve the irradiation of target tissues with light. To further enhance selectivity and potency, numerous molecularly targeted photosensitizers and photoactive nanoparticles have been developed. Active targeting typically involves harnessing the affinity between a ligand and a cell surface receptor for improved accumulation in the targeted tissue. Targeting ligands including peptides, proteins, aptamers and small molecules have been explored for phototherapy. In this review, recent examples of targeted nanomaterials used in phototherapy are summarized.