Optical Characteristics of Indocyanine Green J-Aggregates Induced by Cisplatin for Phototheranostic Applications

Understanding the formulation parameters for engineering indocyanine green J-aggregate lipid nanocapsules and solid lipid nanoparticles as promising photothermal agents

Indocyanine green J-aggregate (IJA) is a promising photothermal (PTT) agent that has recently been utilised in preclinical studies for cancer diagnostics and treatment. The unique properties, such as the red-shift absorption band and longer wavelengths, are behind IJA's superior thermal stability compared to its monomeric ICG. Loading IJA into nanoparticles (NPs) has proven advantageous in enhancing its in vivo targeting of various cancer models. However, the loading of IJA into more complex lipids, such as lipid nanocapsules (LNCs) and solid lipid nanoparticles (SLNs), has not been reported. The present work focuses on investigations of the effect of formulation parameters on pre-formed IJA (p-IJA) stability and the formation of p-IJA-loaded LNCs and SLNs, thus enhancing their theranostic applications. We investigated the effect of the lipid shell of LNCs and the lipid core of SLN on p-IJA stability. Our findings demonstrated the significant role of lipophilic surfactants (Span 85) and a high-melting-point lipid core (sodium stearate) in enhancing the p-IJA ratio and heating capacity following loading into SLNs. More importantly, p-IJA-SLN enhanced the optical stability of p-IJA in a range of biological media, such as serum proteins, blood, and collagen. Furthermore, lyophilised p-IJA-SLNs were successfully obtained after long-term storage. Overall, p-IJA-loaded lipid NPs could provide a promising platform for various applications, including photoacoustic imaging, PTT, photodynamic therapy (PDT), and combination therapy with chemotherapeutics.

Biodegradable lipid bilayer-assisted indocyanine green J- aggregates for photothermal therapy: Formulation, in vitro toxicity and in vivo clearance

Indocyanine green (ICG) J-aggregates (IJA) are a unique form of aggregation that exhibits superior properties to monomeric ICG. Despite their higher photoacoustic (PA) signals for imaging and heating stability during photothermal therapy (PTT), they exhibit low stability under a biological milieu. Our group previously proposed a simple procedure for in-situ preparation of IJA into liposomes, accelerating their formation and optical properties. To comprehend their potential applications, we systematically investigated the effect of the lipid bilayer composition on ICG J-aggregation and stability. Moreover, their in vitro compatibility and photothermal toxicity in monolayers and cancer spheroids, besides their in vivo biodistribution and clearance were evaluated. Our findings revealed the importance of high cholesterol and PEG-lipid content and low charged lipids (∼ 5 mol %) in liposomes to promote a high IJA/ICG ratio and, thus, high heating stability. More importantly, IJA-liposomes revealed high biocompatibility in monolayer and cancer spheroids with efficient photothermal toxicity. Finally, IJA-liposomes were cleared from the body without toxicity. Interestingly, IJA-liposomes mainly showed lower affinity to the liver than monomeric ICG, resulting in higher renal clearance. Overall, our biodegradable IJA-liposomes could be an excellent alternative to gold-based agents suitable for PA imaging and cancer PTT.

Molecular Engineering of Ultrabright Biomimetic NanoGhost for Site-Selective Tumor Imaging and Biodistribution

Optically active ultrabright imaging agents are shown to delineate tumor location with deep tissue visualization in pre noclinical tumor models. NanoGhosts (NGs) particles are reconstructed from the cell membrane and integrated with organic fluorophores to attain ultra-brightness for solid tumor imaging. Moreover, the integration of amphiphilic and lipophilic molecules reveals structural characteristics of NGs (≈70 nm), which also alter their brightness. Upon intravenous administration (10 mg kg-1 single dose), these ultrabright NGs (778 MESF) enable the high-resolution of tumor site and real-time tracking of vital organs with high-contrast fluorescence signals. Engineered biomimetic NGs demonstrates better resolution and tissue penetration as compared to the clinically approved indocyanine green (ICG). High precision in tumor detection (0.5 h) and strong tumor retention (24 h which is further up to 30th day) without affecting healthy tissues ensure the future scope of NGs in early-stage cancer imaging. These findings suggest that these NGs mimic the biological characteristics of native cells, enabling them to evade immune clearance and target the solid tumor naturally.

Tailoring Indocyanine Green J-Aggregates for Imaging, Cancer Phototherapy, and Drug Delivery: A Review

Indocyanine green J-aggregates (ICG-Jagg) have emerged as a significant subject of interest in biomedical applications due to their unique optical properties, tunable size, and excellent biocompatibility. This comprehensive review aims to provide an in-depth exploration of ICG-Jagg, with a focus on elucidating the diverse facets of their preparation and the factors that influence the preparation process. Additionally, the review discusses their applications in biomedical diagnostics, such as imaging and contrast agents, as well as their utilization in drug delivery and various phototherapeutic interventions.

Indocyanine green J-aggregate (IJA) theranostics: Challenges and opportunities

Indocyanine green is an FDA-approved fluorescent imaging dye used for determining cardiac output, hepatic function, liver blood flow, and retinal perfusion. It has been investigated preclinically in photoacoustic imaging and photothermal therapy (PTT); however, ICG photodegradation limits its biomedical applications. An aggregated form of ICG, known as J-aggregate (IJA), exhibits superior photoacoustic signals and thermal stability than the monomeric ICG. Nevertheless, IJA still suffers from low stability in the biological milieu, and short in vivo blood circulation. To address these limitations, a range of nanocarriers have been developed to enhance IJA stability and performance. This review focuses on IJA potentials and limitations, besides the recent development of IJA-loaded nanocarriers, particularly for cancer imaging and therapy.

A Facile Approach to Producing Liposomal J-Aggregates of Indocyanine Green with Diagnostic and Therapeutic Potential

Liposomal J-Aggregates of Indocyanine Green (L-JA) can serve as a biocompatible and biodegradable nanoparticle for photoacoustic imaging and photothermal therapy. When compared to monomeric IcG, L-JA are characterized by longer circulation, improved photostability, elevated absorption at longer wavelengths, and increased photoacoustic signal generation. However, the documented methods for production of L-JA vary widely. We developed an approach to efficiently form IcG J-aggregates (IcG-JA) directly in liposomes at elevated temperatures. Aggregating within fully formed liposomes ensures particle uniformity and allows for control of J-aggregate size. L-JA have unique properties compared to IcG. L-JA provide significant contrast enhancement in photoacoustic images for up to 24 hours after injection, while IcG and unencapsulated IcG-JA are cleared within an hour. L-JA allow for more accurate photoacoustic-based sO2 estimation and particle tracking compared to IcG. Furthermore, photothermal heating of L-JA with an 852nm laser is demonstrated to be more effective at lower laser powers than conventional 808nm lasers for the first time. The presented technique offers an avenue for formulating a multi-faceted contrast agent for photoacoustic imaging and photothermal therapy that offers significant advantages over other conventional agents.

PEGylated chitosan-coated nanophotosensitizers for effective cancer treatment by photothermal-photodynamic therapy combined with glutathione depletion

The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) has emerged as a promising strategy for cancer treatment. However, the poor photostability and photothermal conversion efficiency (PCE) of organic small-molecule photosensitizers, and the intracellular glutathione (GSH)-mediated singlet oxygen scavenging largely decline the antitumor efficacy of PTT and PDT. Herein, a versatile nanophotosensitizer (NPS) system is developed by ingenious incorporation of indocyanine green (ICG) into the PEGylated chitosan (PEG-CS)-coated polydopamine (PDA) nanoparticles via multiple π-π stacking, hydrophobic and electrostatic interactions. The PEG-CS-covered NPS showed prominent colloidal and photothermal stability as well as high PCE (ca 62.8 %). Meanwhile, the Michael addition between NPS and GSH can consume GSH, thus reducing the GSH-induced singlet oxygen scavenging. After being internalized by CT26 cells, the NPS under near-infrared laser irradiation produced massive singlet oxygen with the aid of thermo-enhanced intracellular GSH depletion to elicit mitochondrial damage and lipid peroxide formation, thus leading to ferroptosis and apoptosis. Importantly, the combined PTT and PDT delivered by NPS effectively inhibited CT26 tumor growth in vivo by light-activated intense hyperthermia and redox homeostasis disturbance. Overall, this work presents a new tactic of boosting antitumor potency of ICG-mediated phototherapy by PEG-CS-covered NPS.

Drug Repositioning of Metformin Encapsulated in PLGA Combined with Photothermal Therapy Ameliorates Rheumatoid Arthritis

Purpose

Rheumatoid arthritis (RA) is a highly prevalent form of autoimmune disease that affects nearly 1% of the global population by causing severe cartilage damage and inflammation. Despite its prevalence, previous efforts to prevent the perpetuation of RA have been hampered by therapeutics' cytotoxicity and poor delivery to target cells. The present study exploited drug repositioning and nanotechnology to convert metformin, a widely used antidiabetic agent, into an anti-rheumatoid arthritis drug by designing poly(lactic-co-glycolic acid) (PLGA)-based spheres. Moreover, this study also explored the thermal responsiveness of the IL-22 receptor, a key regulator of Th-17, to incorporate photothermal therapy (PTT) into the nanodrug treatment.

Materials and Methods

PLGA nanoparticles were synthesized using the solvent evaporation method, and metformin and indocyanine green (ICG) were encapsulated in PLGA in a dropwise manner. The nanodrug's in vitro anti-inflammatory properties were examined in J744 and FLS via real-time PCR. PTT was induced by an 808 nm near-infrared (NIR) laser, and the anti-RA effects of the nanodrug with PTT were evaluated in DBA/1 collagen-induced arthritis (CIA) mice models. Further evaluation of anti-RA properties was carried out using flow cytometry, immunofluorescence analysis, and immunohistochemical analysis.

Results

The encapsulation of metformin into PLGA allowed the nanodrug to enter the target cells via macropinocytosis and clathrin-mediated endocytosis. Metformin-encapsulated PLGA (PLGA-MET) demonstrated promising anti-inflammatory effects by decreasing the expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), increasing the expression of anti-inflammatory cytokines (IL-10 and IL-4), and promoting the polarization of M1 to M2 macrophages in J774 cells. The treatment of the nanodrug with PTT exhibited more potent anti-inflammatory effects than free metformin or PLGA-MET in CIA mice models.

Conclusion

These results demonstrated that PLGA-encapsulated metformin treatment with PTT can effectively ameliorate inflammation in a spatiotemporal manner.

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.