Laser-Induced Heating of Dextran-Coated Mesocapsules Containing Indocyanine Green

Enhancing the photothermal properties of indocyanine green in melanoma spheroids via encapsulation in Span 80-containing lipid nanocapsules

Indocyanine green (ICG), a well-known photosensitiser, has shown potential in photothermal therapy (PTT) for cancer treatment, but its effectiveness is limited by poor skin penetration and rapid clearance. To address this, lipid nanocapsules (LNCs) were used as nanocarriers to enhance ICG's cellular uptake and photothermal (PT) performance in melanoma cells. Utilising our recently developed Span 80-modified LNCs (LNC100-S8) with high biocompatibility and enhanced cellular uptake in B16F10 melanoma cells, ICG was loaded into LNC100-S8 using the phase inversion temperature method. The results showed that ICG encapsulation at 4.5 mg/mL maintained small LNC sizes (95-105 nm). Moreover, the heating capacity of ICG in LNCs was approximately 1.5 times higher than free ICG, achieving temperature increases over 10 °C post-irradiation. In cell cancer monolayers, LNC100-S8 enhanced ICG uptake by 1.5 times compared to free ICG and reduced cell viability to 50 % following 808 nm laser irradiation. More promisingly, ICG-LNC100-S8 combined with laser irradiation significantly reduced three-dimensional B16F10 spheroids size up to 11 days post-treatment compared to free ICG. Overall, our findings validate LNC100-S8, as promising nanocarriers for enhancing ICG-based PTT, supporting their potential applications in vivo to treat melanoma and other skin cancers.

DDS-type near-infrared light absorber enables deeper lesion treatment in laser photothermal therapy while avoiding damage to surrounding organs

The efficacy of drug delivery system (DDS)-type near-infrared (NIR) absorbing agents in enhancing laser photothermal therapy is widely acknowledged. Despite the acknowledged efficacy, the therapeutic advantages of photothermal therapy using DDS-type NIR-absorbing agents over simple photothermal therapy without such agents have not been fully elucidated. This study was designed to investigate two primary objectives: firstly, the ability of DDS-type NIR-absorbing agents to induce cell death at greater depths within tumors, and secondly, their capacity to minimize collateral damage to adjacent healthy organs. To investigate these objectives, we employed a combination of indocyanine green lactosome-a DDS-type NIR-absorbing agent-and a precision-controlled laser hyperthermia system. An orthotopic neuroblastoma tumor model was used to closely simulate clinical conditions. The findings revealed that photothermal therapy using the DDS-type NIR-absorbing agent not only facilitates deeper penetration of cell death within tumors but also significantly mitigates thermal damage to surrounding healthy tissues, when compared to simple phototherapy without the agent. Furthermore, the combined treatment significantly prolonged the survival periods of the animals involved. This study is the first to analyze these therapeutic efficacies using quantitative data from an orthotopic tumor animal model and substantiated the potential of DDS-type NIR-absorbing agents to deepen the therapeutic impact of photothermal therapy while safeguarding vital organs, thereby enhancing overall treatment outcomes.

Near-infrared light activatable niosomes loaded with indocyanine green and plasmonic gold nanorods for theranostic applications

Light-mediated theranostic platforms involve the use of agents (small molecules/nanomaterials), which can absorb light to produce either heat or reactive chemical species (RCS) and emit fluorescence. Such platforms are advantageous in the field of personalized medicine, as they provide enhanced diagnostic capabilities, improved therapeutic efficiencies, and can also simultaneously monitor the treatment outcomes using imaging modalities. Specifically, agents absorbing near-infrared (NIR) light can provide minimal scattering, low autofluorescence, superior spatio-temporal resolution, and deeper tissue penetration depths. Gold nanorods (GNR) and indocyanine green (ICG) are two agents known to absorb light in the NIR region. GNR can provide tunable plasmonic properties, while ICG is an FDA-approved NIR fluorophore. However, the use of ICG and GNR suffers from various limitations, such as photobleaching, non-specificity, toxicity, and aggregation in solution. To overcome these limitations, herein, we report on NIR light-activatable niosomes loaded with GNR and ICG for cancer theranostic applications. Both agents were encapsulated into non-ionic surfactant-based biocompatible niosomes to form ICG-GNR@Nio with superior loading efficiencies and enhanced properties. ICG-GNR@Nio offers excellent storage stability, photostability, elevated temperature rise and generation of reactive oxygen species (ROS) upon 1064 nm laser irradiation. Subsequently, the enhanced phototherapeutic capabilities mediated by ICG-GNR@Nio were validated in the in vitro cellular experiments. Overall, ICG-GNR@Nio-based theranostic platforms can provide a significant benchmark in the improved diagnosis and therapeutic capabilities for biomedical clinicians to tackle various diseases.

Virus-like nanoparticles as a theranostic platform for cancer

Virus-like nanoparticles (VLPs) are natural polymer-based nanomaterials that mimic viral structures through the hierarchical assembly of viral coat proteins, while lacking viral genomes. VLPs have received enormous attention in a wide range of nanotechnology-based medical diagnostics and therapies, including cancer therapy, imaging, and theranostics. VLPs are biocompatible and biodegradable and have a uniform structure and controllable assembly. They can encapsulate a wide range of therapeutic and diagnostic agents, and can be genetically or chemically modified. These properties have led to sophisticated multifunctional theranostic platforms. This article reviews the current progress in developing and applying engineered VLPs for molecular imaging, drug delivery, and multifunctional theranostics in cancer research.

Smart NIR-II croconaine dye-peptide for enhanced photo-sonotheranostics of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is associated with high morbidity and mortality rates. The development of novel nanomaterials represents an important direction for precise HCC theranostics. The combination of photothermal and sonodynamic therapy has provided great benefits for HCC therapy. Theranostic agents in the second near-infrared window (NIR-II, 1000-1700 nm) show great prospects because of their extraordinarily high detection sensitivity, resolution, and deep penetration. Methods: A sharp pH-sensitive self-assembling Glypican-3 (GPC3)-binding peptide (GBP) dye, CR-PEG-GBP, was developed as an intelligent nanoprobe for NIR-II imaging and photoacoustic (PA) imaging-guided photothermal therapy (PTT) and sonodynamic therapy (SDT) of HCC. Results: This small molecule assembled nanoprobe exhibited advantageous properties, such as responding to a decrease in pH (from normal tissue (pH 7.4) to the tumor microenvironment (pH ~6.5)) and aggregating - from small nanoprobes (<20 nm at pH 7.4) - into large nanoparticles (>160 nm at pH 6.5 and >510 nm at pH 5.5) that enables enhanced imaging and therapeutic effects. Because CR-PEG-GBP can self-aggregate in situ in an acidic tumor microenvironment, it shows high tumor accumulation and long tumor retention time, while being excretable from normal tissues and safe. Conclusions: This intelligent self-assembling small molecule strategy provides a simple yet efficient solution for HCC theranostics and may open up new avenues for designing clinically translatable probes for HCC treatment.

Indocyanine Green Assembled Nanobubbles with Enhanced Fluorescence and Photostability

Indocyanine green (ICG) is a near-infrared (NIR) fluorescent dye for extensive biomedical application. However, its fluorescence intensity is limited by its poor aqueous stability and concentration-dependent aggregation. To overcome these limitations, ICG self-assembled nanobubbles (ICG-NBs) with an average size of 244.6 nm are fabricated. In the ICG-NB assembled structures, the ICG molecules are arrayed on the gas-liquid interface by the hydrophobic interaction with the gas core and hydrophilic heads with water. Results show that ICG-NBs exhibited good monodispersity and excellent fluorescence and size stability. Compared with ICG solution, the ICG-NBs indicate the enhanced quantum yield and fluorescence intensity. The surface-enhanced Raman scattering (SERS) spectra and fluorescence lifetime measurement demonstrate that the ICG molecule assembled NBs could result in the changes of molecular vibration and time-resolved intensity decays of ICG. Thus, the ICG-NBs could be more beneficial for optical imaging in clinical applications in the future.

Shifting the absorption to the near-infrared region and inducing a strong photothermal effect by encapsulating zinc(II) phthalocyanine in poly(lactic-co-glycolic acid)-hyaluronic acid nanoparticles

By using an oil-in-water single emulsion method, a series of multifunctional hybrid nanoparticles (NPs) were prepared which consisted of a core of poly(lactic-co-glycolic acid) (PLGA) with a lipoid shell of n-hexadecylamine-substituted hyaluronic acid (HA), encapsulating a zinc(II) phthalocyanine-based photosensitizer (ZnPc). As determined by laser light scattering, these hybrid NPs labeled as ZnPc@PLGA-HA NPs possessed a hydrodynamic diameter of 280 nm and a surface charge of -30 mV, showing high stability in serum. The Q-band absorption of ZnPc exhibited a large red-shift from 674 nm for free ZnPc in dimethylsulfoxide to 832 nm for this nanosystem in water. Upon light irradiation at 808 nm, the encapsulated ZnPc induced a strong photothermal effect instead of photodynamic action, which is usually observed for ZnPc-containing NPs. The tumor-targeting effect of these NPs due to the HA coating was investigated against the human colorectal adenocarcinoma HT29 cells and human lung carcinoma A549 cells, both of which overexpress cluster determinant 44 (CD44) receptors, using the CD44-negative human normal hepatic LO2 cells as a negative control. The photothermal cell-killing effect of these NPs was significantly higher for the two CD44-positive cell lines than that for the negative control. Their in vivo photothermal efficacy was also examined on HT29 tumor-bearing nude mice. Upon irradiation, the NPs caused significant temperature increase at the tumor site and ablation of the tumor. The results showed that these multifunctional NPs could serve as an effective photothermal agent for targeted photothermal therapy. Statement of significance Phthalocyanines are well-known photosensitizers for photodynamic therapy. By encapsulating these molecules into various nanoplatforms, a range of multifunctional photosensitizing systems have been developed for cancer therapy. In this study, we have demonstrated that by careful selection of phthalocyanines and the nanocarriers, as well as the self-assembly and encapsulation methods, the encapsulated phthalocyanine molecules could switch the photoinduced action from photodynamic therapy to photothermal therapy as a result of the enhanced aggregation of the macrocyclic molecules in the nanoparticles. The unique packing of the molecules also resulted in a large red-shift of the Q-band absorption to 832 nm, facilitating the in vitro and in vivo photothermal treatment.

Indocyanine Green Loaded Modified Mesoporous Silica Nanoparticles as an Effective Photothermal Nanoplatform

Photothermal therapy possesses great advantages for the treatment of drug-resistant tumors. Herein, Near Infrared (NIR)-triggered photothermal nanoparticles were developed through loading indocyanine green (ICG), a kind of NIR dye, into amino group-modified silica nanoparticles (SiO₂-NH₂ NPs). SiO₂-NH₂ NPs were prepared with immobilization of the amino groups into the framework of silica nanoparticles (SiO₂ NPs) by employing (3-aminopropyl)-triethoxysilane (APTES). Before and after the modification of the amino group, the particle sizes of SiO₂ NPs showed similar value, around 100 nm. ICG was further adsorbed into SiO₂-NH₂ NPs by electrostatic attraction to enable SiO₂-NH₂@ICG NPs as a kind of photothermal agent. The loading rate of ICG to SiO₂-NH₂ was greatly increased compared to unmodified SiO₂, and the stability of ICG was also improved. Moreover, the SiO₂-NH₂@ICG NPs exhibited efficient photothermal effects due to ICG transforming laser power into local heat through the connected ICG, when NIR laser irradiation turned on for a couple of minutes. Finally, the in vitro antitumor efficacy of SiO₂-NH₂@ICG NPs was investigated by recording cell proliferation rate and further chronicled the apoptotic morphology evidence by a Calcein-AM/PI fluorescent staining assay, indicating the efficient photothermal targeted therapy for the HepG2 tumor cells.

Fluorescence imaging-guided multifunctional liposomes for tumor-specific phototherapy for laryngeal carcinoma

Reliable diagnosis and efficient targeted therapy are important and may lead to the effective treatment of laryngeal carcinoma. Multifunctional nano-theranostic agents demonstrate great potential in tumor theranostic applications. Thus, herein, we report novel targeting multifunctional theranostic nanoparticles, internalized RGD (iRGD)-modified indocyanine green (ICG) encapsulated liposomes (iLIP_ICG), for imaging-guided photothermal therapy (PTT) and photodynamic therapy (PDT) for the treatment of laryngeal carcinoma. The iRGD-PEG-DSPE lipid endowed iLIP_ICG with high affinity for tumor vascular targeting, tumor-penetration and tumor cell targeting. The in vivo results showed that iLIP_ICG exhibited excellent blood circulation and tumor accumulation. iLIP_ICG could be spatially and temporally controlled, simultaneously producing hyperthermia and reactive oxygen species as well as a fluorescence-guided effect through ICG to ablate laryngeal carcinoma cells under irradiation from an 808 nm laser. iLIP_ICG generated synergistic photodynamic-photothermal cytotoxicity against Hep-2 cells, resulting in the efficient ablation of laryngeal carcinoma. Thus, the iLIP_ICG system provides a promising strategy to improve the precision imaging and effective phototherapy for the treatment of laryngeal carcinoma.

"Off/on" fluorescence imaging-guided cancer diagnosis and multi-modal therapy

An efficient theranostic nanoplatform responding to tumour microenvironments with characters of simple and flexible combinations owns great potential in cancer diagnosis and therapy. Herein, a series of triblock copolymers, mPEG-b-PDPA-b-P(nBMA-r-cystamine) (EPB), were synthesized and among them, the structure of EPB-3 was optimized for both fluorescence imaging-guided cancer diagnosis and multi-modal therapy with good biocompatibility. (1) The self-assembled nanoparticles of EPB-3-ICG₁ obtained by conjugating one ICG on EPB-3 via S-S bonds effectively performed reduction-sensitive OFF/ON fluorescence signal transition, thus inducing tumour cell-specific amplified fluorescence imaging in vitro and in vivo. (2) By entrapping Au nanorods into the co-assembled NPs of EPB-3 and EPB-3-ICG₁, EPB-3-ICG₁@Au NPs could synchronously induce strong tumour fluorescence imaging and high local photothermal effect, indicating the potential of imagine-guided photothermal therapy. (3) EPB-3 NPs could efficiently co-load paclitaxel (PTX) and ICG to form stable EPB-3@PTX@ICG NPs, which provided long periods of intracellular pH-sensitive sustainable drug release and highly enhanced apoptosis of 4T1 cells in vitro by the chemo-photothermal effect. Excitingly, a single intravenous injection of EPB-3@PTX@ICG NPs followed by a one-time local near-infrared light (NIR, 808 nm) irradiation treatment for 10 min could lead to significant inhibition of tumour growth, avoiding tumor metastasis and extending the survival of mice. All the above-mentioned results suggest that EPB-3 provides a nanoplatform with the characters of simple structure, convenience of use and flexible combination, holding potential for multi-modal diagnosis and therapy.

Laser-induced heating for in situ DNA replication and detection in microchannels

This study proposes a method for in situ local deoxyribonucleic acid (DNA) replication and detection in a long DNA strand through laser-induced heating and strong avidin-biotin binding. To achieve the target DNA replication, dielectrophoresis was generated to stretch and immobilise DNA strands on both ends of the electrode. Subsequently, local DNA sequences were replicated using thermal cycles generated by laser-induced heating. Replicated double-stranded DNA products were captured in situ on a solid surface and detected using the fluorescence intensity of quantum dots (Qdots). The results revealed that after six laser-induced thermal cycles, the replicated local DNA sequence could be detected by analysing the difference between Qdot fluorescent intensity before and after replication. The proposed method is expected to improve the efficiency of biosample gene sequence analysis.

Improved Stable Indocyanine Green (ICG)-Mediated Cancer Optotheranostics with Naturalized Hepatitis B Core Particles

In recent years, hepatitis B core protein virus-like particle (HBc VLP) is an impressive biomaterial, which has attracted considerable attention due to favorable properties such as structural stability, high uptake efficiency, and biocompatibility in biomedical applications. Heretofore, only a few attempts have been made to apply it in physical, chemical, and biological therapy for cancer. In this study, a tumor-targeting RGD-HBc VLP is first fabricated through genetic engineering. For image-guided cancer phototherapy, indocyanine green (ICG) is loaded into RGD-HBc VLP via a disassembly/reassembly pathway and electrostatic attraction with high efficiency. The self-assembled stable RGD-HBc VLP significantly improves body retention (fourfold longer), aqueous stability, and target specificity of ICG. Remarkably, these positive reformations promote more accurate and sensitive imaging of U87MG tumor, as well as prolonged tumor destruction in comparison with free ICG. Moreover, the photothermal and photodynamic effect on tumors are quantitatively differentiated by multiple linear regression analysis. Overall, less-potent medicinal ICG can be perfectly rescued by bioengineered HBc VLP to realize enhanced cancer optotheranostics.

Photothermally Amplified Therapeutic Liposomes for Effective Combination Treatment of Cancer

Near-infrared photothermal therapy has been investigated extensively with regard to selective tumor eradication, yet its clinical translation has been limited because of the absence of FDA-approvable agents with effective phototherapeutic function and minimal systemic toxicity. In this work, we developed photothermally amplified therapeutic liposomes in an attempt to synergize chemotherapy and hyperthermia for effective cancer phototherapy. The anticancer drug cisplatin and the photothermal agent indocyanine green (ICG) were encapsulated in a thermosensitive liposomal formulation at the lipid/ICG ratio maximizing the ICG loading efficiency. These liposomes released cytotoxic cisplatin molecules selectively via ICG-mediated photothermal stimulation. In phototherapeutic studies, these liposomes amplified therapeutic effects both in vitro in cancer cells and in vivo in mouse tumor models significantly over chemotherapy or photothermal therapy alone. We believe that these photothermally amplified therapeutic liposomes composed solely of already FDA-approved components (cisplatin, ICG, and phospholipids) have enormous potential for clinical translation in treating various tumors compatible with laser irradiation.

Indocyanine Green-holo-Transferrin Nanoassemblies for Tumor-Targeted Dual-Modal Imaging and Photothermal Therapy of Glioma

Active-targeted cancer imaging and therapy of glioma has attracted much attention in theranostic nanomedicine. As a promising tumor-targeting ligand, holo-transferrin (holo-Tf) has been applied for enhancing delivery of nanotheranostics. However, holo-Tf-based nanoassemblies for active targeting mediated multimodal imaging and therapeutics have not been previously reported. Here, we develop a one-step method for the preparation of holo-Tf-indocyanine green (holo-Tf-ICG) nanoassemblies for fluorescence (FL) and photoacoustic (PA) dual-modal imaging and photothermal therapy (PTT) of glioma. The nanoassemblies are formed by hydrophobic interaction and hydrogen bonds between holo-Tf and ICG, which exhibit excellent active tumor-targeting and high biocompability. The brain tumor with highly expressed Tf receptor can be clearly observed with holo-Tf-ICG nanoassemblies base on FL and PA dual-modal imaging in subcutaneous and orthotopic glioma models. Under the near-infrared laser irradiation, the holo-Tf-ICG nanoassemblies accumulated in tumor regions can efficiently convert laser energy into hyperthermia for tumor ablation. The novel theranostic nanoplatform holds great promise for precision diagnosis and treatment of glioma.

Liposomal Indocyanine Green for Enhanced Photothermal Therapy

In this study, we engineered liposomal indocyanine green (ICG) to maximize its photothermal effects while maintaining the fluorescence intensity. Various liposomal formulations of ICG were prepared by varying the lipid composition and the molar ratio between total lipid and ICG, and their photothermal characteristics were evaluated under near-infrared irradiation. We showed that the ICG dispersity in the liposomal membrane and its physical interaction with phospholipids were the main factors determining the photothermal conversion efficiency. In phototherapeutic studies, the optimized formulation of liposomal ICG showed greater anticancer effects in a mouse tumor model compared with other liposomal formulations and the free form of ICG. Furthermore, we utilized liposomal ICG to visualize the metastatic lymph node around the primary tumor under fluorescence imaging guidance and ablate the lymph node with the enhanced photothermal effect, indicating the potential for selective treatment of metastatic lymph node.

Indocyanine Green-Loaded Silver Nanoparticle@Polyaniline Core/Shell Theranostic Nanocomposites for Photoacoustic/Near-Infrared Fluorescence Imaging-Guided and Single-Light-Triggered Photothermal and Photodynamic Therapy

Photoacoustic (PA)/near-infrared fluorescence (NIRF) dual-modal imaging-guided phototherapy has been wide explored very recently. However, the development of high-efficiency and simplified-performed theranostic system for amplifying imaging-guided photothermal therapy/photodynamic therapy (PTT/PDT) is still a great challenge. Herein, a single-light-triggered indocyanine green (ICG)-loaded PEGylation silver nanoparticle core/polyaniline shell (Ag@PANI) nanocomposites (ICG-Ag@PANI) for PA/NIRF imaging-guided enhanced PTT/PDT synergistic effect has been successfully constructed. In this study, the synthesized Ag@PANI nanocomposites are utilized not only as the promising photothermal agent but also as potential nanovehicles for loading photosensitizer ICG via π-π stacking and hydrophobic interaction. The as-prepared ICG-Ag@PANI possesses many superior properties such as strong optical absorption in the near-infrared (NIR) region, enhanced photostability of ICG, as well as outstanding NIR laser-induced local hyperthermia and reactive oxygen species (ROS) generation. In the in vivo study, PA/NIRF dual-modal imaging confirms the accumulation and distribution of ICG-Ag@PANI in the tumor region via enhanced permeability and retention (EPR) effect. Moreover, the PTT effect of ICG-Ag@PANI rapidly raised the tumor temperature to 56.8 °C within 5 min. It is also demonstrated that the cytotoxic ROS generation ability of ICG is well maintained after being loaded onto Ag@PANI nanocomposites. Remarkably, in comparison with PTT or PDT alone, the single 808 nm NIR laser-triggered combined PTT/PDT therapy exhibits enhanced HeLa cells lethality in vitro and tumor growth inhibition in vivo.

Laser-induced heating integrated with a microfluidic platform for real-time DNA replication and detection

This study developed a microfluidic platform for replicating and detecting DNA in real time by integrating a laser and a microfluidic device composed of polydimethylsiloxane. The design of the microchannels consisted of a laser-heating area and a detection area. An infrared laser was used as the heating source for DNA replication, and the laser power was adjusted to heat the solutions directly. In addition, strong biotin–avidin binding was used to capture and detect the replicated products. The biotin on one end was bound to avidin and anchored to the surface of the microchannels, whereas the biotin on the other end was bound to the quantum dots (Qdots). The results showed that the fluorescent intensity of the Qdots bound to the replicated products in the detection area increased with the number of thermal cycles created by the laser. When the number of thermal cycles was ≥10, the fluorescent intensity of the Qdots was directly detectable on the surface of the microchannels. The proposed method is more sensitive than detection methods entailing gel electrophoresis.

A targeted agent with intercalation structure for cancer near-infrared imaging and photothermal therapy

A new targeted photothermal agent is synthesized by co-intercalation of indocyanine green (ICG) and folic acid (FA) into the layered double hydroxide (LDH), which can be potentially used in cancer NIR imaging and photothermal therapy (PTT) field.

(177)Lu-Labeled Cerasomes Encapsulating Indocyanine Green for Cancer Theranostics

This Article reported the fabrication of a robust theranostic cerasome encapsulating indocyanine green (ICG) by incorporating 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy(polyethylene glycol)2000]-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid monoamide (DSPE-PEG2000-DOTA), followed by chelating radioisotope of (177)Lu. Its applications in optical and nuclear imaging of tumor uptake and biodistribution, as well as photothermal killing of cancer cells, were investigated. It was found that the obtained cerasome could act efficiently as fluorescence contrast agent as well as nuclear imaging tracer. Encapsulating ICG into cerasome could protect ICG from degradation, aggregation, and fast elimination from body, resulting in remarkable improvement in near-infrared fluorescence imaging, photothermal stability, and in vivo pharmacokinetic profile. Both fluorescence and nuclear imaging showed that such agent could selectively accumulate in tumor site after intravenous injection of the cerasome agent into Lewis lung carcinoma tumor bearing mice, resulting in efficient photothermal ablation of tumor through a one-time NIR laser irradiation at the best time window. The ability to track the uptake of cerasomes on a whole body basis could provide researchers with an excellent tool for developing cerasome-based drug delivery agents, especially the strategy of labeling cerasomes with theranostic radionuclide (177)Lu, enabling the ability of the (177)Lu-labeled cerasomes for radionuclide cancer therapy and even the combined therapy.

An imagable and photothermal "Abraxane-like" nanodrug for combination cancer therapy to treat subcutaneous and metastatic breast tumors

A new "Abraxane-like" nanotheranostic formulation self-assembled from three clinically approved agents, human serum albumin, paclitaxel, and indocyanine green, is developed. Utilizing such a newly formulated nanodrug, combined photothermal and chemotherapy is conducted under the guidance of imaging, not only effectively eliminating subcutaneous tumors, but also significantly inhibiting the development of metastatic tumors in this proof-of-concept study.

Robust ICG theranostic nanoparticles for folate targeted cancer imaging and highly effective photothermal therapy

Folic acid (FA)-targeted indocyanine green (ICG)-loaded nanoparticles (NPs) (FA-INPs) were developed to a near-infrared (NIR) fluorescence theranostic nanoprobe for targeted imaging and photothermal therapy of cancer. The FA-INPs with good monodispersity exhibited excellent size and fluorescence stability, preferable temperature response under laser irradiation, and specific molecular targeting to MCF-7 cells with FA receptor overexpression, compared to free ICG. The FA-INPs enabled NIR fluorescence imaging to in situ monitor the tumor accumulation of the ICG. The cell survival rate assays in vitro and photothermal therapy treatments in vivo indicated that FA-INPs could efficiently targeted and suppressed MCF-7 cells and xenograft tumors. Hence, the FA-INPs are notable theranostic NPs for imaging-guided cancer therapy in clinical application.

REVIEW OF METAL, CARBON AND POLYMER NANOPARTICLES FOR INFRARED PHOTOTHERMAL THERAPY

The aim of this review is to provide an up-to-date overview of nanoparticles developed for use as photothermal therapy agents (PTT) over the past five years. The main emphasis is on nanoparticles that absorb near infrared (NIR) light for PTT of cancer. Mild hyperthermia, including drug delivery, versus thermal ablation is also discussed. Recent advances in the synthesis of highly anisotropic novel metal nanoparticles for PTT are described. New metals and metal oxide complexes, as well as the use of quantum dots for PTT and as imaging agents are newer areas of development that are explained. This review also highlights current progress in the development of carbon nanoparticles, including reduced graphene oxide for both thermal ablation as well as drug delivery. The review culminates in the recent use electrically conductive polymer nanoparticles for hyperthermia. The advantages and unique features of these contemporary nanoparticles being used for PTT are highlighted. The goal of the present work is to describe the recent evolution of nanoparticles for NIR stimulated PTT, and highlight the innovations and future directions.

Effects of nanoencapsulation and PEGylation on biodistribution of indocyanine green in healthy mice: quantitative fluorescence imaging and analysis of organs

Near-infrared nanoconstructs present a potentially effective platform for site-specific and deep tissue optical imaging and phototherapy. We have engineered a polymeric nanocapsule composed of polyallylamine hydrochloride (PAH) chains cross-linked with sodium phosphate and doped with indocyanine green (ICG) toward such endeavors. The ICG-doped nanocapsules were coated covalently with polyethylene glycol (5000 daltons) through reductive amination. We administrated the constructs by tail vein injection to healthy mice. To characterize the biodistribution of the constructs, we performed in vivo quantitative fluorescence imaging and subsequently analyzed the various extracted organs. Our results suggest that encapsulation of ICG in these PEGylated constructs is an effective approach to prolong the circulation time of ICG and delay its hepatic accumulation. Increased bioavailability of ICG, due to encapsulation, offers the potential of extending the clinical applications of ICG, which are currently limited due to rapid elimination of ICG from the vasculature. Our results also indicate that PAH and ICG-doped nanocapsules (ICG-NCs) are not cytotoxic at the levels used in this study.

Near infrared dye indocyanine green doped silica nanoparticles for biological imaging

Indocyanine green (ICG) is an FDA-approved near infrared (NIR) fluorescent dye used in clinical imaging. However, its applications remain limited due to its short half-life, nonspecific plasma binding, optical instability, and poor aqueous stability. Dye doped silica nanoparticles provide an effective barrier in keeping the dye away from the surrounding environment, but ICG cannot be encapsulated into silica easily by conventional methods. In this study, ICG molecules ion-paired with a cationic polymer polyethylenimine (PEI) were successfully encapsulated into a silica matrix to form ICG doped silica nanoparticles by using the Stöber method. Pairing with PEI reduced self-quenching of fluorescence by preventing the aggregation of ICG molecules in silica nanoparticles. Dye leakage was also reduced to the level of 3-6% loss in 5 days. NIR fluorescence images of ICG doped silica NPs below a 2.0 cm thick porcine muscle sample illuminated by NIR light were obtained.

Multifunctionality of indocyanine green-loaded biodegradable nanoparticles for enhanced optical imaging and hyperthermia intervention of cancer

The aim of this study was to develop and characterize multifunctional biodegradable and biocompatible poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with indocyanine green (ICG) as an optical-imaging contrast agent for cancer imaging and as a photothermal therapy agent for cancer treatment. PLGA-ICG nanoparticles (PIN) were synthesized with a particle diameter of 246±11 nm, a polydispersity index of 0.10±0.03, and ICG loading efficiency of 48.75±5.48%. PIN were optically characterized with peak excitation and emission at 765 and 810±5 nm, a fluorescence lifetime of 0.30±0.01 ns, and peak absorbance at 780 nm. The cytocompatibility study of PIN showed 85% cell viability till 1-mg/ml concentration of PIN. Successful cellular uptake of ligand conjugated PIN by prostate cancer cells (PC3) was also obtained. Both phantom-based and in vitro cell culture results demonstrated that PIN (1) have the great potential to induce local hyperthermia (i.e., temperature increase of 8 to 10°C) in tissue within 5 mm both in radius and in depth; (2) result in improved optical stability, excellent biocompatibility with healthy cells, and a great targeting capability; (3) have the ability to serve as an image contrast agent for deep-tissue imaging in diffuse optical tomography.

Enhanced tumor treatment using biofunctional indocyanine green-containing nanostructure by intratumoral or intravenous injection

Indocyanine green (ICG) is a conventional dye that can be used in clinical near-infrared (NIR) imaging, and it is also an effective light absorber for laser-mediated photothermal therapy. However, applications of ICG were limited due to its fast degradation in aqueous media and quick clearance from the body. Herein, an ICG-containing nanostructure, ICG-PL-PEG, was developed for photothermal therapy, which was self-assembled by ICG and phospholipid-polyethylene glycol (PL-PEG). Our in vitro and in vivo experiments demonstrated that ICG-PL-PEG suspension was more efficient in producing a NIR-dependent temperature increase than ICG alone, due to the increase of ICG monomers from the addition of PL-PEG to match the central wavelength of the 808 nm laser. When conjugated with integrin α(v)β(3) monoclonal antibody (mAb), ICG-PL-PEG could be selectively internalized and retained in target tumor cells. Irradiation of an 808 nm laser after intravenous administration of ICG-PL-PEG-mAb resulted in tumor suppression in mice, while ICG alone had only limited effect. This is the first time an ICG-containing nanostructure has been used through systemic administration to achieve an efficient in vivo photothermal effect for cancer treatment. Therefore, ICG-PL-PEG could be used as a fluorescent marker as well as a light-absorber for imaging-guided photothermal therapy. All the components of ICG-PL-PEG have been approved for human use. Therefore, this unique ICG-containing nanostructure has great potential in clinical applications.

Effect of polyethylene glycol coatings on uptake of indocyanine green loaded nanocapsules by human spleen macrophages in vitro

Near-infrared (NIR) optically active nanoparticles are promising exogenous chromophores for applications in medical imaging and phototherapy. Since nanoparticles can be rapidly eliminated from the body by cells of the reticuloendothelial system, a thriving strategy to increase their blood circulation time is through surface modification with polyethylene glycol (PEG). We constructed polymeric nanocapsules loaded with indocyanine green (ICG), an FDA-approved NIR dye, and coated with aldehyde-terminated PEG. Using optical absorbance spectroscopy and flow cytometry, we investigated the effect of PEG coating and molecular weight (MW) of PEG [5000 and 30,000 Daltons (Da)] on the phagocytic content of human spleen macrophages incubated with ICG-containing nanocapsules (ICG-NCs) between 15 to 360 min. Our results indicate that surface coating with PEG is an effective method to reduce the phagocytic content of ICG-NCs within macrophages for at least up to 360 min of incubation time. Coating the surface of ICG-NCs with the low MW PEG results in lower phagocytic content of ICG-NCs within macrophages for at least up to 60 min of incubation time as compared to ICG-NCs coated with the high MW PEG. Surface coating of ICG-NCs with PEG is a promising approach to prolong vasculature circulation time of ICG for NIR imaging and phototherapeutic applications.

Optical nano-constructs composed of genome-depleted brome mosaic virus doped with a near infrared chromophore for potential biomedical applications

We have engineered an optical nanoconstruct composed of genome-depleted brome mosaic virus doped with indocyanine green (ICG), an FDA-approved near-infrared (NIR) chromophore. Constructs are highly monodispersed with standard deviation of ±3.8 nm from a mean diameter of 24.3 nm. They are physically stable and exhibit a high degree of optical stability at physiological temperature (37 °C). Using human bronchial epithelial cells, we demonstrate the effectiveness of the constructs for intracellular optical imaging in vitro, with greater than 90% cell viability after 3 h of incubation. These constructs may serve as a potentially nontoxic and multifunctional nanoplatform for site-specific deep-tissue optical imaging, and therapy of disease.

Near infrared imaging with nanoparticles

Near infrared imaging has presented itself as a powerful diagnostic technique with potential to serve as a minimally invasive, nonionizing method for sensitive, deep tissue diagnostic imaging. This potential is further realized with the use of nanoparticle (NP)-based near infrared (NIR) contrast agents that are not prone to the rapid photobleaching and instability of their organic counterparts. This review discusses applications that have successfully demonstrated the utility of nanoparticles for NIR imaging, including NIR-emitting semiconductor quantum dots (QDs), resonant gold nanoshells, and dye-encapsulating nanoparticles. NIR QDs demonstrate superior optical performance with exceptional fluorescence brightness stability. However, the heavy metal composition and high propensity for toxicity hinder future application in clinical environments. NIR resonant gold nanoshells also exhibit brilliant signal intensities and likewise have none of the photo- or chemical-instabilities characteristic of organic contrast agents. However, concerns regarding ineffectual clearance and long-term accumulation in nontarget organs are a major issue for this technology. Finally, NIR dye-encapsulating nanoparticles synthesized from calcium phosphate (CP) also demonstrate improved optical performances by shielding the component dye from undesirable environmental influences, thereby enhancing quantum yields, emission brightness, and fluorescent lifetime. Calcium phosphate nanoparticle (CPNP) contrast agents are neither toxic, nor have issues with long-term sequestering, as they are readily dissolved in low pH environments and ultimately absorbed into the system. Though perhaps not as optically superior as QDs or nanoshells, these are a completely nontoxic, bioresorbable option for NP-based NIR imaging that still effectively improves the optical performance of conventional organic agents.

Self-assembly synthesis, tumor cell targeting, and photothermal capabilities of antibody-coated indocyanine green nanocapsules

New colloidal materials that can generate heat upon irradiation are being explored for photothermal therapy as a minimally invasive approach to cancer treatment. The near-infrared dye indocyanine green (ICG) could serve as a basis for such a material, but its encapsulation and subsequent use are difficult to carry out. We report the three-step room-temperature synthesis of approximately 120-nm capsules loaded with ICG within salt-cross-linked polyallylamine aggregates, and coated with antiepidermal growth factor receptor (anti-EGFR) antibodies for tumor cell targeting capability. We studied the synthesis conditions such as temperature and water dilution to control the capsule size and characterized the size distribution via dynamic light scattering and scanning electron microscopy. We further studied the specificity of tumor cell targeting using three carcinoma cell lines with different levels of EGFR expression and investigated the photothermal effects of ICG containing nanocapsules on EGFR-rich tumor cells. Significant thermal toxicity was observed for encapsulated ICG as compared to free ICG at 808 nm laser irradiation with radiant exposure of 6 W/cm(2). These results illustrate the ability to design a colloidal material with cell targeting and heat generating capabilities using noncovalent chemistry.

Biodistribution of encapsulated indocyanine green in healthy mice

Indocyanine green (ICG) is a fluorescent probe used in various optically mediated diagnostic and therapeutic applications. However, utility of ICG remains limited by its unstable optical properties and nonspecific localization. We have encapsulated ICG within electrostatically assembled mesocapsules (MCs) to explore its potential for targeted optical imaging and therapy. In this study, we investigate how the surface coating and size of the MCs influences ICG's biodistribution in vivo. ICG was administered intravenously to Swiss Webster mice as a free solution or encapsulated within either 100 nm diameter MCs coated with dextran; 500 nm diameter MCs coated with dextran; or 100 nm diameter MCs coated with 10 nm ferromagnetic iron oxide nanoparticles, themselves coated with polyethylene glycol. ICG was extracted from harvested blood and organs at various times and its amount quantified with fluorescence measurements. MCs containing ICG accumulated in organs of the reticuloendothelial system, namely, the liver and spleen, as well as the lungs. The circulation kinetics of ICG appeared unaffected by encapsulation; however, the deposition within organs other than the liver suggests a different biodistribution mechanism. Results suggest that the capsules' coating influences their biodistribution to a greater extent than their size. The MC encapsulation system allows for delivery of ICG to organs other than the liver, enabling the potential development of new optical imaging and therapeutic strategies.

Stabilization of indocyanine green by encapsulation within micellar systems

Indocyanine green (ICG) is a fluorescence dye that is widely used for near-infrared imaging. Application of this dye is limited by its numerous disadvantageous properties in aqueous solution, including its concentration-dependent aggregation, poor aqueous stability in vitro and low quantum yield. Additionally, ICG is highly bound to nonspecific plasma proteins, leading to rapid elimination from the body with a half-life of 3-4 min. In this study, encapsulation of ICG within various micellar systems was investigated with the aim of overcoming these limitations. The aggregation behavior of different aqueous ICG formulations was studied using cryogenic transmission electron microscopy (cryo-TEM) and absorption spectroscopy. The micellar systems were characterized by their optical properties, particle size distribution, zeta potential and hemolytic activity. Encapsulation efficiency was determined using analytical ultracentrifugation. The best results were achieved for ICG encapsulated within aqueous Solutol HS 15 micelles. This formulation exhibited a lower aggregation behavior, a 3-fold increased quantum yield and high aqueous stability (over 4 weeks) compared to free aqueous ICG. The micelles were found to have an average diameter of 12 nm and a zeta potential close to zero (-2.1 +/- 1.7 mV). Encapsulation efficiency of ICG was high at 95%. The formulation did not display significant hemolytic activity. Consequently, Solutol HS 15 micelles are suitable nanocarriers for ICG which improve the optical properties and stability of the dye.

Preparation and characterization of a polymeric (PLGA) nanoparticulate drug delivery system with simultaneous incorporation of chemotherapeutic and thermo-optical agents

The objective of this study was to develop biodegradable poly(DL-lactide-co-glycolic acid) (PLGA) nanoparticles simultaneously loaded with indocyanine green (ICG) and doxorubicin (DOX). The modified oil in water single emulsion solvent evaporation method was used. To enhance the incorporation of both agents and control particle size, four independent processing parameters including amount of polymer, initial ICG content, initial DOX content, and concentration of poly-vinyl alcohol (PVA) were investigated. The ICG and DOX entrapment in nanoparticles as well as the nanoparticle size were determined. The nanoparticles produced by standardized formulation were in the range of 171+/-2 nm (n=3) with low polydispersity index (0.040+/-0.014, n=3). The entrapment efficiency was determined by spectrofluorometer measurements. The efficiency was 44.4+/-1.6% for ICG and 74.3+/-1.9% for DOX. Drug loading was 0.015+/-0.001%, w/w, for ICG and 0.022+/-0.001%, w/w, for DOX (n=3). The release pattern was biphasic. ICG and DOX loaded-nanoparticle preparation was standardized based on the following parameters: PLGA concentration, PVA concentration and initial drug content.

Polyamine-guided synthesis of anisotropic, multicompartment microparticles

Colloidal particles that have nonuniform bulk or surface compositions are of emerging interest because of their potential applications involving advanced chemical storage and delivery and the self-assembly of novel functional materials. Experimental realization of anisotropic particles is much more difficult than that for particles with uniform bulk and surface composition, however. A new wet-chemical synthesis method to anisotropic microparticles is presented. This approach makes convenient use of the unusual observation of a salt-triggered separation of two water-solubilized polyamines into colloidal aggregates with nonuniform polymer composition. The anisotropic structure of these ionically cross-linked aggregates is explained by the difference in surface tensions of the contained single-polymer domains. Contacting the polymer aggregates with silicic acid or 13-nm silica nanoparticles leads to the charge-driven formation of solid or hollow microspheres, respectively. Depending on the poly(lysine)/poly(allylamine) ratio, the nonuniformity of the polymer aggregates translates to surface patches or internal compartments found in the resultant silica/polymer microparticles. Such hybrid materials with their unique structure could serve as a new basis for targeted chemical delivery and controlled release for potential applications in medicine, food, and cosmetics.

In-vivo fluorescence imaging of mammalian organs using charge-assembled mesocapsule constructs containing indocyanine green

Indocyanine green (ICG) is a fluorescent probe used in clinical imaging. However, its utility remains limited by optical instability, rapid circulation kinetics, and exclusive uptake by the liver. Using mesocapsule (MC) constructs to encapsulate ICG, we have developed a technology to stabilize ICG's optical properties and alter its biodistribution. We present in vivo fluorescence images of mammalian organs to demonstrate the potential application of our ICG encapsulation technology for optical imaging of specific tissues.

Near-infrared emitting fluorophore-doped calcium phosphate nanoparticles for in vivo imaging of human breast cancer

Early detection is a crucial element for the timely diagnosis and successful treatment of all human cancers but is limited by the sensitivity of current imaging methodologies. We have synthesized and studied bioresorbable calcium phosphate nanoparticles (CPNPs) in which molecules of the near-infrared (NIR) emitting fluorophore, indocyanine green (ICG), are embedded. The ICG-CPNPs demonstrate exceptional colloidal and optical characteristics. Suspensions consisting of 16 nm average diameter particles are colloidally stable in physiological solutions (phosphate buffered 0.15 M saline (PBS), pH 7.4) with carboxylate or polyethylene glycol (PEG) surface functionality. ICG-doped CPNPs exhibit significantly greater intensity at the maximum emission wavelength relative to the free constituent fluorophore, consistent with the multiple molecules encapsulated per particle. The quantum efficiency per molecule of the ICG-CPNPs is 200% greater at 0.049 +/- 0.003 over the free fluorophore in PBS. Photostability based on fluorescence half-life of encapsulated ICG in PBS is 500% longer under typical clinical imaging conditions relative to the free dye. PEGylated ICG-CPNPs accumulate in solid, 5 mm diameter xenograft breast adenocarcinoma tumors via enhanced retention and permeability (EPR) within 24 h after systemic tail vein injection in a nude mouse model. Ex situ tissue imaging further verifies the facility of the ICG-CPNPs for deep-tissue imaging with NIR signals detectable from depths up to 3 cm in porcine muscle tissue. Our ex vivo and in vivo experiments verify the promise of the NIR CPNPs for diagnostic imaging in the early detection of solid tumors.

Magnetic resonance imaging guidance for laser photothermal therapy

Temperature distribution is a crucial factor in determining the outcome of laser phototherapy in cancer treatment. Magnetic resonance imaging (MRI) is an ideal method for 3-D noninvasive temperature measurement. A 7.1-T MRI was used to determine laser-induced high thermal gradient temperature distribution of target tissue with high spatial resolution. Using a proton density phase shift method, thermal mapping is validated for in vivo thermal measurement with light-absorbing enhancement dye. Tissue-simulating phantom gels, biological tissues, and tumor-bearing animals were used in the experiments. An 805-nm laser was used to irradiate the samples, with laser power in the range of 1 to 3 W. A clear temperature distribution matrix within the target and surrounding tissue was obtained with a specially developed processing algorithm. The temperature mapping showed that the selective laser photothermal effect could result in temperature elevation in a range of 10 to 45 degrees C. The temperature resolution of the measurement was about 0.37 degrees C with 0.4-mm spatial resolution. The results of this study provide in vivo thermal information and future reference for optimizing laser dosage and dye concentration in cancer treatment.