Enhanced photo-stability, thermal-stability and aqueous-stability of indocyanine green in polymeric nanoparticulate systems

Indocyanine green-mediated photothermal release of lidocaine from genipin-crosslinked gelatin hydrogel in nerve block

Local anesthetic (LA)-induced peripheral nerve block (PNB) is an important part of multimodal analgesia to reduce postoperative pain, accelerate postoperative recovery, and improve clinical prognosis. The duration of LA depends on anesthetics, and the repeated nerve positioning, puncture injection or indwelling catheter is often required to prolong the effect of PNB. In this study, the genipin, was used to crosslink gelatin-based hydrogel, and then co-loaded with indocyanine green (ICG) and lidocaine as an LA-controlled release system (ICG@Lido/Gel and ICG@Lido/gGel). The viscosity of the genipin-crosslinked gelatin hydrogel (gGel) could be controlled by the genipin/gelatin ratio to achieve the slow release of lidocaine. The ICG@Lido/Gel and ICG@Lido/gGel were biocompatible, and could reduce the instant concentration of lidocaine to minimize its direct cytotoxicity. The ICG@Lido/Gel and ICG@Lido/gGel could increase the PNB period to 70.8 min and 77.8 min, respectively. After NIR exposure, the PNB was introduced again and sustained to 20.8 min for ICG@Lido/Gel and 31.7 min for ICG@Lido/gGel. Therefore, the ICG@Lido/gGel could significantly prolong the PNB duration via increasing the residence time of lidocaine at the injection site, slowing the lidocaine release, and triggering the lidocaine release by NIR exposure. The ICG@Lido/gGel may expresses potential as a photothermal-triggered release system for PNB.

Enhanced Fluorescence Imaging of Implants Based on Polyester Copolymers in Combination With MRI

Nowadays, many biodegradable materials are offered for biomedical applications, but there are only a few in vivo methods for their detection and monitoring. In this work, implants based on biodegradable polyester copolymers were labeled with indocyanine green (ICG) for fluorescence imaging in combination with tissue optical clearing (TOC) and magnetic resonance imaging (MRI). The results include in vitro degradation modeling followed by in vivo imaging of copolymer samples that were subcutaneously implanted in BALB/c mice. TOC with 70% glycerol has been demonstrated to significantly improve sample visualization. The TOC efficiency parameter Q demonstrated the variability of effects correlating with the timing of follow-up in the postimplantation period. It has been shown that nonhealing wounds, peri-implantation inflammation, or fibrosis, confirmed by MRI, affect the effectiveness of TOC in the range from Q = -30% to 70%.

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.

Focused starvation of tumor cells using glucose oxidase: A comprehensive review

Starvation therapy targets the high metabolic demand of tumor cells. It primarily leans over the consumption of intracellular glucose and simultaneous blockade of alternative metabolic pathways. The strategy involves the use of glucose oxidase (GOx) for catalyzing the conversion of glucose into gluconic acid and hydrogen peroxide. Under these conditions, metabolic re-programming of tumor cells enables the utilization of substrates such as amino acids, fatty acids and lipids. This can be overcome by co-administration of chemo-, photo- and immuno-therapeutics together with glucose oxidase. Targeted delivery of glucose oxidase at tumor site can be enabled with the use of nanoformulations. In this review, we highlight that the outcomes of starvation therapy can be improved using rationally developed nano-formulations. It is possible to load synergistically acting bioactives in these formulations and deliver in site-specific manner and hence achieve the elimination of tumors cells with greater efficacy.

Versatile Thermo-Sensitive liposomes with HSP inhibition and Anti-Inflammation for synergistic Chemo-Photothermal to inhibit breast cancer metastasis

Photothermal therapy (PTT) is a prospective therapeutic method for breast cancer. However, excess inflammatory response induced by PTT may aggravate tumor metastasis. Meanwhile, the overexpressed heat shock proteins (HSPs) by cancer cells can protect them from hyperthermia during PTT. Therefore, to attenuate the PTT-induced inflammation and inhibit tumor metastasis, a folate receptor-targeted thermo-sensitive liposome (BI-FA-LP) co-loading Berberine (BBR) and Indocyanine green (ICG) was developed. BI-FA-LP utilized enhanced permeability and retention (EPR) effect and FA receptor-mediated endocytosis to selectively accumulate at tumor, reducing off-target toxicity during the treatment. After targeting to the tumor site, BBR and ICG were released from BI-FA-LP upon laser irradiation, and ICG showed good photothermal performance, while BBR inhibited HSP70 and HSP90 expression during PTT, exerting chemo-photothermal synergetic anti-tumor effect. Moreover, BBR could suppress the PTT induced inflammation, thus inhibiting tumor metastasis and ameliorating tissue injury. Thus, this versatile liposome provided a new strategy to enhance PTT and anti-inflammatory effects for breast cancer treatment.

Effect of oxygen generating nanozymes on indocyanine green and IR 820 mediated phototherapy against oral cancer

The hypoxic environment within a solid tumor is a limitation to the effectiveness of photodynamic therapy. Here, we demonstrate the use of oxygen generating nanozymes (CeO2, Fe3O4, and MnO2) to improve the photodynamic effect. The optimized combination of process parameters for irradiation was obtained using the Box Behnken experimental design. Indocyanine green, IR 820, and their different combinations with oxygen generators were studied for their effect on oral carcinoma. Dynamic light scattering technique showed the average particle size of CeO2, MnO2, and Fe3O4 to be 211 ± 16, and 157 ± 28, 143 ± 19 nm with PDI of 0.23, 0.28 and 0.20 and a zeta potential of -2.6 ± 0.45, -2.4 ± 0.60 and  -6.1 ± 0.23 mV, respectively. The formation of metal oxides was confirmed using UV-visible, FTIR, and X-ray photon spectroscopies. The amount of dissolved oxygen produced by CeO2, MnO2, and Fe3O4 in the presence of H2O2 within 2 min was 1.7 ± 0.15, 1.7 ± 0.16, and 1.4 ± 0.12 mg/l, respectively. Growth inhibition studies in the FaDu oral carcinoma spheroid model showed a significant (P < 0.05) increase in growth reduction from 81 ± 2.9 and 88 ± 2.1% to 97 ± 1.2 and 99 ± 1.0% for ICG and IR 820, respectively, after irradiation (808 nm laser, 1 W/cm2, 5 min) in the presence of CeO2 (25 μg/ml). In conclusion, oxygen-generating nanozymes can improve the photodynamic effect of ICG and IR 820.

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.

Antibody-Conjugated Polymersomes with Encapsulated Indocyanine Green J-Aggregates and High Near-Infrared Absorption for Molecular Photoacoustic Cancer Imaging

Imaging plays a critical role in all stages of cancer care from early detection to diagnosis, prognosis, and therapy monitoring. Recently, photoacoustic imaging (PAI) has started to emerge into the clinical realm due to its high sensitivity and ability to penetrate tissues up to several centimeters deep. Herein, we encapsulated indocyanine green J (ICGJ) aggregate, one of the only FDA-approved organic exogenous contrast agents that absorbs in the near-infrared range, at high loadings up to ∼40% w/w within biodegradable polymersomes (ICGJ-Ps) composed of poly(lactide-co-glycolide-b-polyethylene glycol) (PLGA-b-PEG). The small Ps hydrodynamic diameter of 80 nm is advantageous for in vivo applications, while directional conjugation with epidermal growth factor receptor (EGFR) targeting cetuximab antibodies renders molecular specificity. Even when exposed to serum, the ∼11 nm-thick membrane of the Ps prevents dissociation of the encapsulated ICGJ for at least 48 h with a high ratio of ICGJ to monomeric ICG absorbances (i.e., I895/I780 ratio) of approximately 5.0 that enables generation of a strong NIR photoacoustic (PA) signal. The PA signal of polymersome-labeled breast cancer cells is proportional to the level of cellular EGFR expression, indicating the feasibility of molecular PAI with antibody-conjugated ICGJ-Ps. Furthermore, the labeled cells were successfully detected with PAI in highly turbid tissue-mimicking phantoms up to a depth of 5 mm with the PA signal proportional to the amount of cells. These data show the potential of molecular PAI with ICGJ-Ps for clinical applications such as tumor margin detection, evaluation of lymph nodes for the presence of micrometastasis, and laparoscopic imaging procedures.

Biomimetic nanoplatform with selectively positioned indocyanine green for accurate sentinel lymph node imaging

The status of draining lymph nodes (LNs) is critical for determining the treatment and prognosis of cancer that spreads through the lymphatic system. Indocyanine green (ICG) fluorescence imaging has been widely used in sentinel LN (SLN) biopsy technology and has shown favorable effects. However, this too has its own limitations, such as fluorescence instability and diffusion imaging. In this study, we developed macrophage cell membrane-camouflaged ICG-loaded biomimetic nanoparticles (M@F127-ICG) for accurate SLN imaging. ICG selectively positioned at the hydrophobic-hydrophilic interfaces of pluronic F127 micelles protected itself from quenching in aqueous solution, thereby maintaining fluorescence stability and improving fluorescence intensity. In addition, to further improve the aggregation in SLN, the micellar surface was coated with a layer of biomimetic macrophage cell membrane to target LN-resident macrophages. In vivo fluorescence imaging demonstrated that M@F127-ICG significantly enhanced the fluorescence signal and improved the imaging efficiency of SLN. Thus, selectively positioning ICG in the biomimetic nanoplatform enhanced the fluorescence intensity and stability, providing a novel tracer for timely and accurate SLN imaging.

Indocyanine Green-Loaded Halloysite Nanotubes as Photothermal Agents

Photothermal nanoparticles with light-to-heat conversion properties have gained interest in recent years and have been used in a variety of applications. Herein, indocyanine green (ICG), which is commonly employed as a photothermal agent suffering from low photostability, was loaded into halloysite nanotubes (HNTs) resulting in photothermal HNT-ICG nanohybrids. The photothermal heating patterns of the prepared photothermal nanohybrids as a result of near-infrared (NIR) irradiation were carefully examined. The nanohybrids reached a temperature of 216 °C in 2 min under NIR light, and in contrast to free NIR, the ICG loaded into HNTs remained stable over 10 heating and cooling cycles. Moreover, HNT-ICG nanohybrids incorporated into polyacrylonitrile (PAN) were electrospun into nanofibers for use as photothermal nanofibers, and composite nanofibers, which heat up to 79.3 °C under 2 min of NIR irradiation, were obtained. To demonstrate the potential of the PAN/HNT-ICG nanofibers as light-activated antibacterial nanofibers, their NIR light-activated killing activity on Staphylococcus aureus (S. aureus) cells has been explored. The composite nanofibers reduced the number of bacteria on their surface by 7log upon 10 min of NIR irradiation. Encapsulation of ICG in HNTs as a carrier has been demonstrated as an effective way to stabilize ICG and incorporate it into materials and coatings without compromising its functionality.

Nanomaterials: a promising multimodal theranostics platform for thyroid cancer

Thyroid cancer is the most prevalent malignant neoplasm of the cervical region and endocrine system, characterized by a discernible upward trend in incidence over recent years. Ultrasound-guided fine needle aspiration is the current standard for preoperative diagnosis of thyroid cancer, albeit with limitations and a certain degree of false-negative outcomes. Although differentiated thyroid carcinoma generally exhibits a favorable prognosis, dedifferentiation is associated with an unfavorable clinical course. Anaplastic thyroid cancer, characterized by high malignancy and aggressiveness, remains an unmet clinical need with no effective treatments available. The emergence of nanomedicine has opened new avenues for cancer theranostics. The unique features of nanomaterials, including multifunctionality, modifiability, and various detection modes, enable non-invasive and convenient thyroid cancer diagnosis through multimodal imaging. For thyroid cancer treatment, nanomaterial-based photothermal therapy or photodynamic therapy, combined with chemotherapy, radiotherapy, or gene therapy, holds promise in reducing invasiveness and prolonging patient survival or alleviating pain in individuals with anaplastic thyroid carcinoma. Furthermore, nanomaterials enable simultaneous diagnosis and treatment of thyroid cancer. This review aims to provide a comprehensive survey of the latest developments in nanomaterials for thyroid cancer diagnosis and treatment and encourage further research in developing innovative and effective theranostic approaches for thyroid cancer.

Dual-targeted delivery of paclitaxel and indocyanine green with aptamer-modified ferritin for synergetic chemo-phototherapy

The combination of phototherapy and chemotherapy has become attractive and effective cancer treatment. However, the accurate delivery of both chemo-phototherapy drugs to the target site as well as the development of high-efficient phototherapy and chemotherapy drugs remain major challenges. In this study, indocyanine green (ICG) and paclitaxel (PTX)-loaded aptamer ferritin (HAS1411-PTX-ICG) was developed as a biocompatible nanoplatform for combined chemo/photothermal/photodynamic (PTT/PDT) therapy that was safe and highly effective against tumors. HAS1411 was prepared by coupling aptamer AS1411 to the surface of human H chain ferritin (HFtn) by the carbon diimide method to further enhance the targeting of HFtn. Both ICG and PTX were effectively encapsulated in the HAS1411 by incubation at 60 ℃. Moreover, under near-infrared (NIR) light irradiation, HAS1411 enhanced the photothermal effect and cell internalization of ICG, as well as the production of reactive oxygen species in cancer cells. HAS1411-PTX-ICG displayed effective cytotoxicity and a significant tumor spheroids inhibitory effect owning to the improved internalization of PTX and ICG mediated by TfR1 and nucleolin dual receptors. Co-loaded PTX combined with ICG can produce chemo/PTT/PDT under near-infrared (NIR) light irradiation, enhancing the anti-tumor effect. The dual-targeting HAS1411 nanocarrier developed in this study can be a promising delivery system for cancer therapy and the fabricated HAS1411-PTX-ICG possesses potential application in chemo-phototherapy.

Detection of Tumour-Targeted IRDye800CW Tracer with Commercially Available Laparoscopic Surgical Systems

(1) Introduction: Near-infrared fluorescence (NIRF) combined with tumour-targeted tracers, such as bevacizumab-800CW, could aid surgical decision-making. This study explored the use of IRDye800CW, conjugated to bevacizumab, with four commercially available NIRF laparoscopes optimised for indocyanine green (ICG). (2) Methods: A (lymph node) phantom was made from a calibration device for NIRF and tissue-mimicking material. Serial dilutions of bevacizumab-800CW were made and ICG functioned as a reference. System settings, working distance, and thickness of tissue-mimicking material were varied to assess visibility of the fluorescence signal and tissue penetration. Tests were performed with four laparoscopes: VISERA ELITE II, Olympus; IMAGE1 S™ 4U Rubina, KARL STORZ; ENDOCAM Logic 4K platform, Richard Wolf; da Vinci Xi, Intuitive Surgical. (3) Results: The lowest visible bevacizumab-800CW concentration ranged between 13-850 nM (8-512 times diluted stock solution) for all laparoscopes, but the tracer was not visible through 0.8 cm of tissue in all systems. In contrast, ICG was still visible at a concentration of 0.4 nM (16,384 times diluted) and through 1.6-2.4 cm of tissue. Visibility and tissue penetration generally improved with a reduced working distance and manually adjusted system settings. (4) Conclusion: Depending on the application, bevacizumab-800CW might be sufficiently visible with current laparoscopes, but optimisation would widen applicability of tumour-targeted IRDye800CW tracers.

DNA-Immobilized Fluorescent Polystyrene Nanoparticles as Probes with Tunable Detection Limits

DNA-immobilized nanoparticle probes show high target specificity; thus, they are employed in various bioengineering and biomedicine applications. When the nanoparticles employed are dye-loaded polymer particles, the resulting probes have the additional benefit of biocompatibility and versatile surface properties. In this study, we construct DNA-immobilized fluorescent polystyrene (PS) nanoparticles through controlled surface reactions. PS nanoparticles with surface carboxyl groups are utilized, and amine-functionalized dye molecules and capture DNAs are covalently immobilized via a one-pot reaction. We show that the surface chemistry employed allows for quantitative control over the number of fluorescent dyes and DNA strands immobilized on the PS nanoparticle surfaces. The nanoparticles thus prepared are then used for DNA detection. The off state of the nanoprobe is achieved by hybridizing quencher-functionalized DNAs (Q-DNAs) to the capture DNAs immobilized on nanoparticle surfaces. Target-DNAs (T-DNAs) are detected by the displacement of the prehybridized Q-DNAs. The nanoprobes show successful detection of T-DNAs with high sequence specificity and long-term stability. They also show excellent detection sensitivity, and the detection limit can be tuned by adjusting the capture DNA-to-dye ratio.

Size effect of liposomes on centimeter-deep ultrasound-switchable fluorescence imaging and ultrasound-controlled release

Liposomes have been widely used in both medical imaging and drug delivery fields due to their excellent biocompatibility and easy surface modification. Recently our lab reported for the first-time the implementation of temperature-sensitive and indocyanine green (ICG)-encapsulated liposome microparticles for in vivo ultrasound-switchable fluorescence (USF) imaging. A previous study showed that liposome microparticles achieved USF imaging in centimeter-deep tissue. This study aimed to control the size of liposomes at the nanoscale and study the size effect on the USF imaging depth. Also, we explored the feasibility of combining USF imaging with ultrasound-controlled release. Liposomes were synthesized via the hydration method and the size was controlled by an extruding process. Characterization parameters, including fluorescence profile, spectra, size, stability, encapsulation efficiency, and ultrasound-controlled release, were evaluated. USF imaging in blood serum was conducted successfully in a phantom model, and an imaging depth study was conducted at 1.0 cm and 2.5 cm and confirmed that nano-sized liposomes had a stronger USF signal than micron-sized liposomes. Additionally, releasing tests indicated that both ultrasound power and exposure time affected the release efficiency in that increasing the power and extending the exposure time led to higher release efficiency. Above all, this study shows the potential for using liposomes for USF imaging and ultrasound-controlled release.

Biocompatible and Photostable Photoacoustic Contrast Agents as Nanoparticles Based on Bodipy Scaffold and Polylactide Polymers: Synthesis, Formulation, and In Vivo Evaluation

We have designed a new Bodipy scaffold for efficient in vivo photoacoustic (PA) imaging of nanoparticles commonly used as drug nanovectors. The new dye has an optimized absorption band in the near-infrared window in biological tissue and a low fluorescence quantum yield that leads to a good photoacoustic generation efficiency. After Bodipy-initiated ring-opening polymerization of lactide, the polylactide-Bodipy was formulated into PEGylated nanoparticles (NPs) by mixing with PLA-PEG at different concentrations. Formulated NPs around 100 nm exhibit excellent PA properties: an absorption band at 760 nm and a molar absorption coefficient in between that of molecular PA absorbers and gold NPs. Highly improved photostability compared to cyanine-labeled PLA NPs as well as innocuity in cultured macrophages were demonstrated. After intravenous injection in healthy animals, NPs were easily detected using a commercial PA imaging system and spectral unmixing, opening the way to their use as theranostic agents.

Photodisruption of the Inner Limiting Membrane: Exploring ICG Loaded Nanoparticles as Photosensitizers

The inner limiting membrane (ILM) represents a major bottleneck hampering efficient drug delivery to the retina after intravitreal injection. To overcome this barrier, we intend to perforate the ILM by use of a light-based approach which relies on the creation of vapor nanobubbles (VNBs) when irradiating photosensitizers with high intensity laser pulses. Upon collapse of these VNBs, mechanical effects can disrupt biological structures. As a photosensitizer, we explore indocyanine green (ICG) loaded nanoparticles (NPs) specifically designed for our application. In light of this, ICG liposomes and PLGA ICG NPs were characterized in terms of physicochemical properties, ICG incorporation and VNB formation. ICG liposomes were found to encapsulate significantly higher amounts of ICG compared to PLGA ICG NPs which is reflected in their VNB creating capacity. Since only ICG liposomes were able to induce VNB generation, this class of NPs was further investigated on retinal explants. Here, application of ICG liposomes followed by laser treatment resulted in subtle disruption effects at the ILM where zones of fully ablated ILM were alternated by intact regions. As the interaction between the ICG liposomes and ILM might be insufficient, active targeting strategies or other NP designs might improve the concept to a further extent.

Role of Doxorubicin on the Loading Efficiency of ICG within Silk Fibroin Nanoparticles

The effective loading or encapsulation of multimodal theranostic agents within a nanocarrier system plays an important role in the clinical development of cancer therapy. In recent years, the silk fibroin protein-based delivery system has been drawing significant attention to be used in nanomedicines due to its biocompatible and biodegradable nature. In this study, silk fibroin nanoparticles (SNPs) have been synthesized by a novel and cost-effective ultrasonic atomizer-based technique for the first time. The fabricated SNPs were coencapsulated by the FDA-approved indocyanine green (ICG) dye and the chemotherapeutic drug doxorubicin (DOX). The synthesized SNPs are spherical, with an average diameter of ∼37 ± 4 nm, and the ICG-DOX-coencapsulated SNPs (ID-SNPs) have a diameter size of ∼47 ± 6 nm. For the first time, here we demonstrate that DOX helps in the higher loading of ICG within the ID-SNPs, which enhances the encapsulation efficiency of ICG by ∼99%. This could be attributed to the interaction of ICG and DOX molecules with the silk fibroin protein, which helps ICG to get loaded more efficiently within these nanoparticles. The overall finding of this study suggests that the ID-SNPs could be utilized for enhanced ICG-complemented multimodal deep-tissue bioimaging and synergistic chemo-photothermal therapy.

Synthesis and Characterization of Diketopyrrolopyrrole-Based Aggregation-Induced Emission Nanoparticles for Bioimaging

Conventional fluorescent dyes have the property of decreasing fluorescence due to aggregation-caused quenching effects at high concentrations, whereas aggregation-induced emission dyes have the property of increasing fluorescence as they aggregate with each other. In this study, diketopyrrolopyrrole-based long-wavelength aggregation-induced emission dyes were used to prepare biocompatible nanoparticles suitable for bioimaging. Aggregation-induced emission nanoparticles with the best morphology and photoluminescence intensity were obtained through a fast, simple preparation method using an ultrasonicator. The optimally prepared nanoparticles from 3,6-bis(4-((E)-4-(bis(40-(1,2,2-triphenylvinyl)-[1,10-biphenyl]-4-yl)amino)styryl)phenyl)-2,5-dihexyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DP-R2) with two functional groups having aggregation-induced emission properties and additional donating groups at the end of the triphenylamine groups were considered to have the greatest potential as a fluorescent probe for bioimaging. Furthermore, it was found that the tendency for aggregation-induced emission, which was apparent for the dye itself, became much more marked after the dyes were incorporated within nanoparticles. While the photoluminescence intensities of the dyes were observed to decrease rapidly over time, the prepared nanoparticles encapsulated within the biocompatible polymers maintained their initial optical properties very well. Lastly, when the cell viability test was conducted, excellent biocompatibility was demonstrated for each of the prepared nanoparticles.

Electrospun SF/PLGA/ICG Composite Nanofibrous Membranes for Potential Wound Healing and Tumor Therapy

Indocyanine green (ICG) is a near-infrared (NIR) organic reagent for clinical bioimaging and phototherapy. It is a suitable photosensitizer for photodynamic antimicrobial chemotherapy (PACT). In this study, various ICG-loaded nanofibrous membranes were prepared. The water vapor transmission rate (WVTR) of SF/PLGA/20ICG was 3040.49 ± 157.11 g·m−2 day−1, which allowed the maintenance of a humid environment above the wound. The growth inhibition rates for S. aureus and E. coli were 91.53% and 87.95%, respectively. The nanofibrous membranes exhibited excellent antimicrobial performance. Cellular experiments showed that the nanofibrous membranes have good cytocompatibility and antitumor efficacy. SF/PLGA/20ICG showed good potential for application in wound healing and cancer therapy.

Extracellular vesicles with high dual drug loading for safe and efficient combination chemo-phototherapy

Extracellular vesicles (EVs) have emerged as biocompatible nanocarriers for efficient delivery of various therapeutic agents, with intrinsic long-term blood circulatory capability and low immunogenicity. Here, indocyanine green (ICG)- and paclitaxel (PTX)-loaded EVs [EV(ICG/PTX)] were developed as a biocompatible nanoplatform for safe and efficient cancer treatment through near-infrared (NIR) light-triggered combination chemo/photothermal/photodynamic therapy. High dual drug encapsulation in EVs was achieved for both the hydrophilic ICG and hydrophobic PTX by simple incubation. The EVs substantially improved the photostability and cellular internalization of ICG, thereby augmenting the photothermal effects and reactive oxygen species production in breast cancer cells upon NIR light irradiation. Hence, ICG-loaded EVs activated by NIR light irradiation showed greater cytotoxic effects than free ICG. EV(ICG/PTX) showed the highest anticancer activity owing to the simultaneous chemo/photothermal/photodynamic therapy when compared with EV(ICG) and free ICG. In vivo study revealed that EV(ICG/PTX) had higher accumulation in tumors and improved pharmacokinetics compared to free ICG and PTX. In addition, a single intravenous administration of EV(ICG/PTX) exhibited a considerable inhibition of tumor proliferation with negligible systemic toxicity. Thus, this study demonstrates the potential of EV(ICG/PTX) for clinical translation of combination chemo-phototherapy.

Simultaneous ultraviolet-C and near-infrared enhancement in heterogeneous lanthanide nanocrystals

Lanthanide-doped nanocrystals that simultaneously convert near-infrared (NIR) irradiation into emission of shorter (ultraviolet-C, UVC) and longer wavelengths (NIR) offer many exciting opportunities for application in drug release, photodynamic therapy, deep-tissue bioimaging, and solid-state lasing. However, a formidable challenge is the development of lanthanide-doped nanocrystals with efficient UVC and NIR emissions simultaneously due to their low conversion efficiency. Here, we report a dye-sensitized heterogeneous core-multishell architecture with enhanced UVC emission and NIR emission under 793 nm excitation. This nanocrystal design efficiently suppresses energy trapping induced by interior lattice defects and promotes upconverted UVC emission from Gd³⁺. Moreover, a significant downshifting emission from Yb³⁺ at 980 nm was also observed owing to an efficient energy transfer from Nd³⁺ to Yb³⁺. Furthermore, by taking advantage of ICG sensitization, we realized a largely enhanced emission from the UVC to NIR spectral region. This study provides a mechanistic understanding of the upconversion and downshifting processes within a heterogeneous architecture while offering exciting opportunities for important biological and energy applications.

Role of photobleaching process of indocyanine green for killing neuroblastoma cells

Indocyanine green (ICG) is an FDA-approved near infrared (NIR) imaging agent for diagnosis and imaging guided surgery. It also exhibits phototoxicity under high-dose NIR irradiation, expanding its application as a photo-therapeutic agent. Since ICG's efficiency as a type II photosensitizer has been controversial due to its low triplet state yield, other mechanisms have been explored. While claims of toxic decomposition products, accompanied by irreversible ICG photobleaching, were proposed as the main mechanism, evidences from systemic studies are lacking. In this work, we aimed to unravel the factors affecting ICG photobleaching and the associated photo-killing effect on neuroblastoma, one of the most common pediatric tumors but often escapes therapy. Specifically, we examined how albumin-induced ICG stabilization affects the ICG photobleaching process, and the effect of photobleached ICG on cell proliferation and viability of neuroblastoma cells. It was found that ICG photobleaching was significant only under aerobic conditions and was more efficient in solutions with higher concentration ICG monomers, which were stabilized from aggregates by the presence of BSA while increasing photobleaching and associated oxygen consumption. Photobleached ICG inhibited cell proliferation, indicating another effect of tumor treatment by ICG. Taken together, while enhanced photobleaching by BSA-bound ICG monomers may reduce the photodynamic effect targeting cellular components, the photoproducts directly contribute to tumor growth inhibition and assist in a secondary mechanism to stop tumor growth.

Chitosan: A versatile bio-platform for breast cancer theranostics

Breast cancer is considered one of the utmost neoplastic diseases globally, with a high death rate of patients. Over the last decades, many approaches have been studied to early diagnose and treat it, such as chemotherapy, hormone therapy, immunotherapy, and MRI and biomarker tests; do not show the optimal efficacy. These existing approaches are accompanied by severe side effects, thus recognizing these challenges, a great effort has been done to find out the new remedies for breast cancer. Main finding: Nanotechnology opened a new horizon to the treatment of breast cancer. Many nanoparticulate platforms for the diagnosis of involved biomarkers and delivering antineoplastic drugs are under either clinical trials or just approved by the Food and Drug Administration (FDA). It is well known that natural phytochemicals are successfully useful to treat breast cancer because these natural compounds are safer, available, cheaper, and have less toxic effects. Chitosan is a biocompatible and biodegradable polymer. Further, it has outstanding features, like chemical functional groups that can easily modify our interest with an exceptional choice of promising applications. Abundant studies were directed to assess the chitosan derivative-based nanoformulation's abilities in delivering varieties of drugs. However, the role of chitosan in diagnostics and theranostics not be obligated. The present servey will discuss the application of chitosan as an anticancer drug carrier such as tamoxifen, doxorubicin, paclitaxel, docetaxel, etc. and also, its role as a theranostics (i.e. photo-responsive and thermo-responsive) moieties. The therapeutic and theranostic potential of chitosan in cancer is promising and it seems that to have a good potential to get to the clinic.

Radiolabeled Silicon-Rhodamines as Bimodal PET/SPECT-NIR Imaging Agents

Radiolabeled fluorescent dyes are decisive for bimodal imaging as well as highly in demand for nuclear- and optical imaging. Silicon-rhodamines (SiRs) show unique near-infrared (NIR) optical properties, large quantum yields and extinction coefficients as well as high photostability. Here, we describe the synthesis, characterization and radiolabeling of novel NIR absorbing and emitting fluorophores from the silicon-rhodamine family for use in optical imaging (OI) combined with positron emission tomography (PET) or single photon emission computed tomography (SPECT), respectively. The presented photostable SiRs were characterized using NMR-, UV-Vis-NIR-spectroscopy and mass spectrometry. Moreover, the radiolabeling conditions using fluorine-18 or iodine-123 were extensively explored. After optimization, the radiofluorinated NIR imaging agents were obtained with radiochemical conversions (RCC) up to 70% and isolated radiochemical yields (RCY) up to 54% at molar activities of g.t. 70 GBq/µmol. Radioiodination delivered RCCs over 92% and allowed to isolate the 123I-labeled product in RCY of 54% at a molar activity of g.t. 7.6 TBq/µmol. The radiofluorinated SiRs exhibit in vitro stabilities g.t. 70% after two hours in human serum. The first described radiolabeled SiRs are a promising step toward their further development as multimodal PET/SPECT-NIR imaging agents for planning and subsequent imaging-guided oncological surgery.

Mn(II)-directed dual-photosensitizers co-assemblies for multimodal imaging-guided self-enhanced phototherapy

Phototherapy has attracted increasing attention in cancer therapy owing to its non-invasive nature, high spatiotemporal selectivity, and negligible side effects. However, a single photosensitizer often exhibits poor photothermal conversion efficiency or insufficient reactive oxygen species (ROS) productivity. Even worse, the ROS can be consumed by tumor overexpressed reductive glutathione, resulting in severely compromised phototherapy. In this paper, we prepared a Mn^II-coordination driven dual-photosensitizers co-assemblies (IMCP) for imaging-guided self-enhanced PDT/PTT. Specifically, a photothermal agent indocyanine green (ICG), a photodynamic agent chlorin e6 (Ce6), and a transition metal ion (Mn^II/III) were chosen to synthesize the nanodrug via coordination-driven co-assembly. The as-prepared IMCP exhibited extremely high photosensitizer payload (96 wt%), excellent physiological stability, and outstanding tumor accumulation. Moreover, the existence of Mn^II not only assists the nanostructure formation but also could competitively coordinate with GSH to minimize the unnecessary ROS consumption, thus improving PDT efficiency. Meanwhile, benefiting from the intrinsic fluorescence, photoacoustic imaging ability of photosensitizers, and the MRI contrast potential of Mn^II/III, IMCP exhibited superior imaging potential for guiding tumor phototherapy. By changing the excitation wavelength suitably, IMCP could realize the switch between PTT and PDT. In short, the dual-PSs co-assembled nanotheranostic has great potential for multi-modal imaging guided phototherapy.

Photophysical Properties of Indocyanine Green in the Shortwave Infrared Region

With the growing development of new contrast agents for optical imaging using near-infrared and shortwave infrared (SWIR) wavelengths, it is essential to have consistent bench-marks for emitters in these regions. Indocyanine green (ICG), a ubiquitous and FDA-approved organic dye and optical imaging agent, is commonly employed as a standard for photophysical properties and biological performance for imaging experiments at these wavelengths. Yet, its reported photophysical properties across organic and aqueous solvents vary greatly in the literature, which hinders its ability to be used as a consistent benchmark. Herein, we measure photophysical properties in organic and aqueous solvents using InGaAs detection (~950-1,700 nm), providing particular relevance for SWIR imaging.

Cyanine Dyes for Photo-Thermal Therapy: A Comparison of Synthetic Liposomes and Natural Erythrocyte-Based Carriers

Cyanine fluorescent dyes are attractive diagnostic or therapeutic agents due to their excellent optical properties. However, in free form, their use in biological applications is limited due to the short circulation time, instability, and toxicity. Therefore, their encapsulation into nano-carriers might help overcome the above-mentioned issues. In addition to indocyanine green (ICG), which is clinically approved and therefore the most widely used fluorescent dye, we tested the structurally similar and cheaper alternative called IR-820. Both dyes were encapsulated into liposomes. However, due to the synthetic origin of liposomes, they can induce an immunogenic response. To address this challenge, we proposed to use erythrocyte membrane vesicles (EMVs) as “new era” nano-carriers for cyanine dyes. The optical properties of both dyes were investigated in different biological relevant media. Then, the temperature stability and photo-stability of dyes in free form and encapsulated into liposomes and EMVs were evaluated. Nano-carriers efficiently protected dyes from thermal degradation, as well as from photo-induced degradation. Finally, a hemotoxicity study revealed that EMVs seem less hemotoxic dye carriers than clinically approved liposomes. Herein, we showed that EMVs exhibit great potential as nano-carriers for dyes with improved stability and hemocompatibility without losing excellent optical properties.

A smart multiantenna gene theranostic system based on the programmed assembly of hypoxia-related siRNAs

The systemic therapeutic utilisation of RNA interference (RNAi) is limited by the non-specific off-target effects, which can have severe adverse impacts in clinical applications. The accurate use of RNAi requires tumour-specific on-demand conditional activation to eliminate the off-target effects of RNAi, for which conventional RNAi systems cannot be used. Herein, a tumourous biomarker-activated RNAi platform is achieved through the careful design of RNAi prodrugs in extracellular vesicles (EVs) with cancer-specific recognition/activation features. These RNAi prodrugs are assembled by splitting and reconstituting the principal siRNAs into a hybridisation chain reaction (HCR) amplification machine. EVs facilitate the specific and efficient internalisation of RNAi prodrugs into target tumour cells, where endogenous microRNAs (miRNAs) promote immediate and autonomous HCR-amplified RNAi activation to simultaneously silence multiantenna hypoxia-related genes. With multiple guaranteed cancer recognition and synergistic therapy features, the miRNA-initiated HCR-promoted RNAi cascade holds great promise for personalised theranostics that enable reliable diagnosis and programmable on-demand therapy.

Emerging indocyanine green-integrated nanocarriers for multimodal cancer therapy: a review

Nanotechnology is a branch of science dealing with the development of new types of nanomaterials by several methods. In the biomedical field, nanotechnology is widely used in the form of nanotherapeutics. Therefore, the current biomedical research pays much attention to nanotechnology for the development of efficient cancer treatment. Indocyanine green (ICG) is a near-infrared tricarbocyanine dye approved by the Food and Drug Administration (FDA) for human clinical use. ICG is a biologically safe photosensitizer and it can kill tumor cells by producing singlet oxygen species and photothermal heat upon NIR irradiation. ICG has some limitations such as easy aggregation, rapid aqueous degradation, and a short half-life. To address these limitations, ICG is further formulated with nanoparticles. Therefore, ICG is integrated with organic nanomaterials (polymers, micelles, liposomes, dendrimers and protein), inorganic nanomaterials (magnetic, gold, mesoporous, calcium, and LDH based), and hybrid nanomaterials. The combination of ICG with nanomaterials provides highly efficient therapeutic effects. Nowadays, ICG is used for various biomedical applications, especially in cancer therapeutics. In this review, we mainly focus on ICG-based combined cancer nanotherapeutics for advanced cancer treatment.

Fusogenic Viral Protein-Based Near-Infrared Active Nanocarriers for Biomedical Imaging

An effective drug delivery system (DDS) relies on an efficient cellular uptake and faster intracellular delivery of theranostic agents, bypassing the endosomal mediated degradation of the payload. The use of viral nanoparticles (VNPs) permits such advancement, as the viruses are naturally evolved to infiltrate the host cells to deliver their genetic material. As a proof of concept, we bioengineered the vesicular stomatitis virus glycoprotein (VSV-G)-based near-infrared (NIR) active viral nanoconstructs (NAVNs) encapsulating indocyanine green dye (ICG) for NIR bioimaging. NAVNs are spherical in size and have the intrinsic cellular-fusogenic properties of VSV-G. Further, the NIR imaging displaying higher fluorescence intensity in NAVNs treated cells suggests enhanced cellular uptake and delivery of ICG by NAVNs compared to the free form of ICG. The overall study highlights the effectiveness of VSV-G-based VNPs as an efficient delivery system for NIR fluorescence imaging.

Safe and Targeted Sonodynamic Cancer Therapy Using Biocompatible Exosome-Based Nanosonosensitizers

Sonodynamic therapy (SDT), wherein sonosensitizers irradiated with ultrasound (US) produce cytotoxic reactive oxygen species (ROS), has garnered great attention as a promising alternative to photodynamic therapy owing to the significantly increased depth of tissue penetration. The development of nanocarriers that can selectively deposit sonosensitizers into tumor tissues without systemic toxicity is crucial to facilitate the translation of SDT to clinical use. In this study, exosomes, a class of naturally occurring nanoparticles, were utilized as nanocarriers for safe and cancer-targeted delivery of a sonosensitizer, indocyanine green (ICG). The exosomes were surface-engineered with an active cancer-targeting ligand, folic acid (FA), to increase the cancer specificity of the ICG-loaded exosomes (ExoICG). The FA-conjugated, ICG-loaded exosomes (FA-ExoICG) greatly improved aqueous stability and cellular uptake of ICG, resulting in significantly increased ROS generation in breast cancer cells. As a result, the FA-ExoICG demonstrated greater sonotoxicity against cancer cells than ExoICG and free ICG. The in vivo study revealed that compared to ExoICG, more FA-ExoICG accumulated in tumors, and their pharmacokinetic properties were superior. Notably, tumor growth in mice was significantly suppressed, without systemic toxicity, by a single intravenous injection of the FA-ExoICG and subsequent US irradiation. Therefore, this study demonstrated that active cancer-targeted FA-ExoICG could serve as effective nanosonosensitizers for safe and targeted cancer treatment.

ROS-responsive liposomes with NIR light-triggered doxorubicin release for combinatorial therapy of breast cancer

BACKGROUND

Reactive oxygen species (ROS)-responsive drug delivery systems (DDSs) are potential tools to minimize the side effects and substantially enhance the therapeutic efficacy of chemotherapy. However, it is challenging to achieve spatially and temporally controllable and accurate drug release in tumor sites based on ROS-responsive DDSs. To solve this problem, we designed a nanosystem combined photodynamic therapy (PDT) and ROS-responsive chemotherapy.

METHODS

Indocyanine green (ICG), an ROS trigger and photosensitizer, and pB-DOX, a ROS-responsive prodrug of doxorubicin (DOX), were coencapsulated in polyethylene glycol modified liposomes (Lipo/pB-DOX/ICG) to construct a combination therapy nanosystem. The safety of nanosystem was assessed on normal HEK-293 cells, and the cellular uptake, intracellular ROS production capacity, target cell toxicity, and combined treatment effect were estimated on human breast cancer cells MDA-MB-231. In vivo biodistribution, biosafety assessment, and combination therapy effects were investigated based on MDA-MB-231 subcutaneous tumor model.

RESULTS

Compared with DOX·HCl, Lipo/pB-DOX/ICG showed higher safety on normal cells. The toxicity of target cells of Lipo/pB-DOX/ICG was much higher than that of DOX·HCl, Lipo/pB-DOX, and Lipo/ICG. After endocytosis by MDA-MB-231 cells, Lipo/pB-DOX/ICG produced a large amount of ROS for PDT by laser irradiation, and pB-DOX was converted to DOX by ROS for chemotherapy. The cell inhibition rate of combination therapy reached up to 93.5 %. After the tail vein injection (DOX equivalent of 3.0 mg/kg, ICG of 3.5 mg/kg) in mice bearing MDA-MB-231 tumors, Lipo/pB-DOX/ICG continuously accumulated at the tumor site and reached the peak at 24 h post injection. Under irradiation at this time point, the tumors in Lipo/pB-DOX/ICG group almost disappeared with 94.9 % tumor growth inhibition, while those in the control groups were only partially inhibited. Negligible cardiotoxicity and no treatment-induced side effects were observed.

CONCLUSIONS

Lipo/pB-DOX/ICG is a novel tool for on-demand drug release at tumor site and also a promising candidate for controllable and accurate combinatorial tumor therapy.

GE11 Peptide Conjugated Liposomes for EGFR-Targeted and Chemophotothermal Combined Anticancer Therapy

How to actively target tumor sites manipulating the controllable release of the encapsulated anticancer drugs and photosensitizers for synergistic anticancer therapy remains a big challenge. In this study, a cancer cell-targeted, near-infrared (NIR) light-triggered and anticancer drug loaded liposome system (LPs) was developed for synergistic cancer therapy. Photosensitizer indocyanine green (ICG) and chemotherapy drug Curcumin (CUR) were coencapsulated into the liposomes, followed by the surface conjugation of GE11 peptide for epidermal growth factor receptor (EGFR) targeting on the cancer cell surface. Strictly controlled by NIR light, GE11 peptide modified and CUR/ICG-loaded LPs (GE11-CUR/ICG-LPs) could introduce hyperthermia in EGFR overexpressed A549 cancer cells for photothermal therapy, which could also trigger the increased release of CUR for enhanced cancer cell inhibition. GE11-CUR/ICG-LPs synergized photochemotherapy could induce reactive oxygen species (ROS) generation and cytoskeleton disruption to activate stronger apoptotic signaling events than the photothermal therapy or chemotherapy alone by regulating Bax/Bcl-2 and PI3K/AKT pathways. This EGFR-targeted drug-delivery nanosystem with NIR sensitivity may potentially serve in more effective anticancer therapeutics with reduced off-target effects.

Polydopamine-Based Nanoparticles for Photothermal Therapy/Chemotherapy and their Synergistic Therapy with Autophagy Inhibitor to Promote Antitumor Treatment

Polydopamine (PDA) has attracted much attention recently due to its strong adhesion capability to most substrates. After combining with organic (such as organic metal framework, micelles, hydrogel, polypeptide copolymer) or inorganic nanomaterials (such as gold, silicon, carbon), polydopamine-based nanoparticles (PDA NPs) exhibit the merging of characteristics. Until now, the preparation methods, polymerization mechanism, and photothermal therapy (PTT) or chemotherapy (CT) applications of PDA NPs have been reported detailly. Since the PTT or CT treatment process is often accompanied by exogenous stimuli, tumor cells usually induce pro-survival autophagy to protect the cells from further damage, which will weaken the therapeutic effect. Therefore, an in-depth understanding of PDA NPs modulated PTT, CT, and autophagy is required. However, this association is rarely reviewed. Herein, we briefly described the relationship between PTT/CT, autophagy, and tumor treatment. Then, the outstanding performances of PDA NPs in PTT/CT and their combination with autophagy inhibitors for tumor synergistic therapy have been summarized. This work is expected to shed light on the multi-strategy antitumor therapy applications of PDA NPs.

Photoacoustic Imaging of Myocardial Infarction Region Using Non-Invasive Fibrin-Targeted Nanoparticles in a Rat Myocardial Ischemia-Reperfusion Model

BACKGROUND AND PURPOSE

Myocardial infarction (MI) is a serious threat to public health. The early identification of MI is important to promote appropriate treatment strategies for patients. Recently, strategies targeting extracellular matrix (ECM) components have gained attention. Fibrin is an ECM protein involved after MI. In this work, we constructed fibrin-targeted nanoparticles (NPs) by co-assembling a fibrin-targeted peptide (CREKA) and indocyanine green (ICG) and used them to enhance photoacoustic (PA) imaging for noninvasive detection of the infarct region to help diagnose MI.

METHODS

ICG NPs modified with CREKA were prepared (CREKA-ICG-LIP NPs). Then, the fundamental characteristics, stability, safety, and targeting ability of the NPs were detected. Finally, in an ischemia-reperfusion (IR) injury model, the performance of the NPs in detecting the infarct region in the model on PA imaging was evaluated.

RESULTS

CREKA-ICG-LIP NPs were successfully constructed and showed excellent basic characteristics, a high safety level, and an excellent targeting ability. After intravenous injection, the CREKA-ICG-LIP NPs accumulated in the injured region in the IR model. Then, the PA signal in the infarct region could be detected by the ultrasound transducer of the Vevo LAZR Photoacoustic Imaging System.

CONCLUSION

This work provides new insights for non-invasive, real-time imaging techniques to detect the region of myocardial injury and help diagnose MI based on a PA imaging system with high sensitivity in optical imaging and deep penetration in ultrasound imaging.

Molecularly targeted photothermal ablation improves tumor specificity and immune modulation in a rat model of hepatocellular carcinoma

Thermal ablation is a standard therapy for patients with hepatocellular carcinoma (HCC). Contemporary ablation devices are imperfect, as they lack tumor specificity. An ideal ablation modality would generate thermal energy only within tumoral tissue. Furthermore, as hyperthermia is known to influence tumor immunity, such a tumor-specific ablation modality may have the ability to favorably modulate the tumor immune landscape. Here we show a clinically relevant thermal ablation modality that generates tumor-specific hyperthermia, termed molecularly targeted photothermal ablation (MTPA), that is based upon the excellent localization of indocyanine green to HCC. In a syngeneic rat model, we demonstrate the tumor-specific hyperthermia generated by MTPA. We also show through spatial and transcriptomic profiling techniques that MTPA favorably modulates the intratumoral myeloid population towards tumor immunogenicity and diminishes the systemic release of oncogenic cytokines relative to conventional ablation modalities.

Nina Muñoz et al. present a novel thermal ablation technique, termed molecularly targeted photothermal ablation (MTPA) that generates hyperthermia specifically within tumor tissue in a clinically-relevant rat model of liver cancer. They further show that MTPA modulates the intratumoral immune profile toward stronger tumor immunogenicity while reducing the release of oncogenic cytokines relative to conventional ablation techniques.

Stabilization of indocyanine green dye in polymeric micelles for NIR-II fluorescence imaging and cancer treatment

One of the most commonly used near infrared (NIR) dyes is indocyanine green (ICG), which has been extensively used for NIR bioimaging, photothermal and photodynamic therapy. However, upon excitation this dye can react with molecular oxygen to form singlet oxygen (SO), which can then cleave ICG to form non-fluorescent debris. In order to reduce the reaction between ICG and oxygen, we used energy transfer (ET) between the former and the NIR dye IR-1061. The two dyes were encapsulated in micelles composed of biocompatible poly(ethylene glycol)-block-poly(ε-caprolactone) (PCL-PEG). Micelles were characterized for their size using dynamic light scattering (DLS) and were found to measure about 35 nm in diameter. Fluorescence emission measurements were conducted to show that the stability of ICG against photodecomposition is increased. Moreover, this increased stability allows the encapsulated dye to generate more heat and for a longer time, compared to its free form. Studies with a SO indicator showed that as more IR-1061 is added to the micelles, less SO is produced. These results show how by changing the amount of added IR-1061 it is possible to tune the heat and SO generated by the system. Cell viability studies demonstrated that while particles were nontoxic under physiological conditions, upon 808 nm irradiation they become potent at eradicating MCF7 cancer cells. Moreover, it was demonstrated that both the increase of temperature and the creation of decomposition debris play a role in the cytotoxic efficacy of the micelles. Dye-loaded micelles that were injected to live mice showed bright fluorescence in the over 1000 nm NIR (OTN-NIR) region, allowing for visualization of blood vessels and internal organs. Most importantly, the encapsulated dyes remained stable for over 30 minutes, gradually accumulating in the liver and spleen. The presence of IR-1061 in addition to the heat-generating dye ICG allowed for simultaneous temperature modification and monitoring. We were able to assess the change in temperature by measuring the change in the fluorescence intensity of IR-1061 in the OTN-NIR region, a range with deep penetration of living tissues. These features illustrate the potential use of ICG/IR-1061 in PCL-PEG micelles as promising candidates for cancer treatment and diagnosis.

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.

Cell Membrane-Inspired Polymeric Vesicles for Combined Photothermal and Photodynamic Prostate Cancer Therapy

Photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as highly prospective therapeutic modalities in cancer therapy. Notwithstanding, a critical challenge still remains in the exploration of an effective strategy to maximize the synergistic efficacy of PTT and PDT due to low photoconversion efficiency. Herein, inspired by the phospholipid bimolecular structure of the cell membrane, bionic cell membrane polymeric vesicles with photothermal/photodynamic synergy for prostate cancer therapy at one wavelength's excitation are constructed in one step by the coordination of hexadecyl trimethyl ammonium bromide (CTAB) from the surface of hydrophobic gold nanorods (AuNRs) with indocyanine green (ICG) and polycaprolactone (PCL), achieving their self-assembly in aqueous solutions. Importantly, the aggregation of the assembly improves the stability of the vesicles, realizing the synergistic effect of PTT and PDT for prostate cancer therapy. After being assembled within polymeric vesicles, bifunctional photosensitizer ICG can generate reactive oxygen species (ROS) and photothermal effect under light treatment. Their ROS not only induce PDT efficacy but also destroy the integrity of the lysosomal membrane, promoting the translocation of ICG and another photosensitizer called gold nanorods (AuNRs) into the cytosol. Moreover, their photothermal effects produced by both photosensitizers are able to engender greater damage to the tumor cells because of the close distance with organelles. This structure manifests good cellular uptake, highly effective tumor accumulation, high photothermal conversion efficiency, and excellent properties of enhanced photobleaching resistance, which are beneficial to ICG-based fluorescence tumor imaging. Using the same near-infrared (NIR) wavelength for excitation, the AuNR/ICG vesicles can reduce the side effect rate of photodamage on the skin. In addition, by generating reactive oxygen species (ROS) and double photothermal effect, the vesicles under NIR excitation can promote the apoptosis of PC3 tumor cells. Taken together, the spontaneous self-assembled AuNR/ICG vesicles exhibit huge potential in advanced-stage prostate cancer therapy, especially for the prostate-specific membrane antigen (PSMA)-negative castration-resistant subtype.

Manganese(II) Texaphyrin: A Paramagnetic Photoacoustic Contrast Agent Activated by Near-IR Light

The NIR absorptivity of the metallotexaphyrin derivatives MMn, MGd, and MLu for photoacoustic (PA)-based imaging is explored in this study. All three complexes demonstrated excellent photostabilities; however, MMn provided the greatest PA signal intensities in both doubly distilled water and RAW 264.7 cells. In vivo experiments using a prostate tumor mouse model were performed. MMn displayed no adverse toxicity to major organs as inferred from hematoxylin and eosin (H&E) staining and cell blood count testing. MMn also allowed for PA-based imaging of tumors with excellent in vivo stability to provide 3D tumor diagnostic information. Based on the present findings and previous magnetic resonance imaging (MRI) studies, we believe MMn may have a role to play either as a stand-alone PA contrast agent or as a single molecule dual modal (PA and MR) imaging agent for tumor diagnosis.

Near-Infrared Activated Cyanine Dyes As Agents for Photothermal Therapy and Diagnosis of Tumors

Today, it has become apparent that innovative treatment methods, including those involving simultaneous diagnosis and therapy, are particularly in demand in modern cancer medicine. The development of nanomedicine offers new ways of increasing the therapeutic index and minimizing side effects. The development of photoactivatable dyes that are effectively absorbed in the first transparency window of biological tissues (700-900 nm) and are capable of fluorescence and heat generation has led to the emergence of phototheranostics, an approach that combines the bioimaging of deep tumors and metastases and their photothermal treatment. The creation of near-infrared (NIR) light-activated agents for sensitive fluorescence bioimaging and phototherapy is a priority in phototheranostics, because the excitation of drugs and/or diagnostic substances in the near-infrared region exhibits advantages such as deep penetration into tissues and a weak baseline level of autofluorescence. In this review, we focus on NIR-excited dyes and discuss prospects for their application in photothermal therapy and the diagnosis of cancer. Particular attention is focused on the consideration of new multifunctional nanoplatforms for phototheranostics which allow one to achieve a synergistic effect in combinatorial photothermal, photodynamic, and/or chemotherapy, with simultaneous fluorescence, acoustic, and/or magnetic resonance imaging.

Blood-Brain Barrier, Blood-Brain Tumor Barrier, and Fluorescence-Guided Neurosurgical Oncology: Delivering Optical Labels to Brain Tumors

Recent advances in maximum safe glioma resection have included the introduction of a host of visualization techniques to complement intraoperative white-light imaging of tumors. However, barriers to the effective use of these techniques within the central nervous system remain. In the healthy brain, the blood-brain barrier ensures the stability of the sensitive internal environment of the brain by protecting the active functions of the central nervous system and preventing the invasion of microorganisms and toxins. Brain tumors, however, often cause degradation and dysfunction of this barrier, resulting in a heterogeneous increase in vascular permeability throughout the tumor mass and outside it. Thus, the characteristics of both the blood-brain and blood-brain tumor barriers hinder the vascular delivery of a variety of therapeutic substances to brain tumors. Recent developments in fluorescent visualization of brain tumors offer improvements in the extent of maximal safe resection, but many of these fluorescent agents must reach the tumor via the vasculature. As a result, these fluorescence-guided resection techniques are often limited by the extent of vascular permeability in tumor regions and by the failure to stain the full volume of tumor tissue. In this review, we describe the structure and function of both the blood-brain and blood-brain tumor barriers in the context of the current state of fluorescence-guided imaging of brain tumors. We discuss features of currently used techniques for fluorescence-guided brain tumor resection, with an emphasis on their interactions with the blood-brain and blood-tumor barriers. Finally, we discuss a selection of novel preclinical techniques that have the potential to enhance the delivery of therapeutics to brain tumors in spite of the barrier properties of the brain.

Near Infrared (NIR) imaging: Exploring biologically relevant chemical space for lanthanide complexes

Near Infrared (NIR) imaging agents are extensively used in the biological or preclinical treatment and diagnosis of a wide range of diseases including cancers and tumors. The current arsenal of NIR compounds are most constituted by organic dyes, polymers, inorganic nanomaterials, whereas Ln molecular complexes explore an alternative approach to design NIR probes that are potentially bring new molecular toolkits into the biomedicine. In this review, NIR imaging agents are categorized according to their molecular sizes, constitution and the key properties and features of each class of compounds are briefly defined wherever possible. To better elucidate the features of Ln complexes, we provide a succinct understanding of sensitization process and molecular Ln luminescence at a mechanistic level, which may help to deliver new insights to design NIR imaging probes. Finally, we used our work on NIR ytterbium (Yb³⁺) probes as an example to raise awareness of exploring biologically relevant chemical space for lanthanide complexes as chemical entities for biological activity.

Nanosponges of circulating tumor-derived exosomes for breast cancer metastasis inhibition

Breast cancer contributes to high mortality rates as a result of metastasis. Tumor-derived exosomes facilitate the development of the premetastatic environment, interacting and inhibiting the normal function of immune cells, thereby forming an immunosuppressive microenvironment for tumor metastasis. Herein, the platelet and neutrophil hybrid cell membrane (PNM) was embellished on a gold nanocage (AuNC) surface called nanosponges and nanokillers (NSKs). NSKs can simultaneously capture and clear the circulating tumor cells (CTCs) and tumor-derived exosomes via high-affinity membrane adhesion receptors, effectively cutting off the connection between exosomes and immune cells. Bionic NSK is loaded with doxorubicin (DOX) and indocyanine green (ICG) for synergic chemo-photothermal therapy. NSKs show greater cellular uptake, deeper tumor penetration, and higher cytotoxicity to tumor cells in comparison to non-coated AuNCs or single-coated AuNCs in vitro. In vivo, the multipurpose NSKs could not only completely ablate the primary tumor but also inhibit breast cancer metastasis with high efficiency in xenograft and orthotopic breast tumor-bearing models. Thus, NSKs could be a promising nanomedicine for the future clinical intervention of breast cancer metastasis.

Liposome-Templated Indocyanine Green J- Aggregates for In Vivo Near-Infrared Imaging and Stable Photothermal Heating

Indocyanine green (ICG) is an FDA-approved near-infrared fluorescent dye that has been used in optical imaging and photothermal therapy. Its rapid in vivo clearance and photo-degradation have limited its application. ICG pharmacokinetics and biodistribution have been improved via liposomal encapsulation, while its photothermal stability has been enhanced by ICG J-aggregate (IJA) formation. In the present work, we report a simple approach to engineer a nano-sized, highly stable IJA liposomal formulation. Our results showed that lipid film hydration and extrusion method led to efficient IJA formation in rigid DSPC liposomes, as supported by molecular dynamics modeling. The engineered DSPC-IJA formulation was nano-sized, and with spectroscopic and photothermal properties comparable to free IJA. Promisingly, DSPC-IJA exhibited high fluorescence, which enabled its in vivo tracking, showing prolonged blood circulation and significantly higher tumor fluorescence signals, compared to free ICG and IJA. Furthermore, DSPC-IJA demonstrated high photo-stability in vivo after multiple cycles of 808 nm laser irradiation. Finally, doxorubicin was loaded into liposomal IJA to utilize the co-delivery capabilities of liposomes. In conclusion, with both liposomes and ICG being clinically approved, our novel liposomal IJA could offer a clinically relevant theranostic platform enabling multimodal imaging and combinatory chemo- and photothermal cancer therapy.