A selenium-based NIR-II photosensitizer for a highly effective and safe phototherapy plan.

High efficiency, stability, long emission wavelength (NIR-II), and good biocompatibility are crucial for photosensitizers in phototherapy. However, current Food and Drug Administration (FDA)-approved organic fluorophores exhibit poor chemical stability and photostability as well as short emission wavelength, limiting their clinical usage. To address this, we developed Se-IR1100, a novel organic photosensitizer with a photostable and thermostable benzobisthiadiazole (BBTD) backbone. By incorporating selenium as a heavy atom and constructing a D-A-D structure, Se-IR1100 exhibits a maximum fluorescence emission wavelength of 1100 nm. Compared with FDA-approved indocyanine green (ICG), DSPE-PEGylated Se-IR1100 nanoparticles exhibit prominent photostability and long-lasting photothermal effects. Upon 808 nm laser irradiation, Se-IR1100 NPs efficiently convert light energy into heat and reactive oxygen species (ROS), inducing cancer cell death in cellular studies and living organisms while maintaining biocompatibility. With salient photostability and a photothermal conversion rate of 55.37%, Se-IR1100 NPs hold promise as a superior photosensitizer for diagnostic and therapeutic agents in oncology. Overall, we have designed and optimized a multifunctional photosensitizer Se-IR1100 with good biocompatibility that performs NIR-II fluorescence imaging and phototherapy. This dual-strategy method may offer novel approaches for the development of multifunctional probes using dual-strategy or even multi-strategy methods in bioimaging, disease diagnosis, and therapy.

Validation of a Three-Dimensional Head and Neck Spheroid Model to Evaluate Cameras for NIR Fluorescence-Guided Cancer Surgery.

Near-infrared (NIR) fluorescence-guided surgery is an innovative technique for the real-time visualization of resection margins. The aim of this study was to develop a head and neck multicellular tumor spheroid model and to explore the possibilities offered by it for the evaluation of cameras for NIR fluorescence-guided surgery protocols. FaDu spheroids were incubated with indocyanine green (ICG) and then included in a tissue-like phantom. To assess the capability of Fluobeam® NIR camera to detect ICG in tissues, FaDu spheroids exposed to ICG were embedded in 2, 5 or 8 mm of tissue-like phantom. The fluorescence signal was significantly higher between 2, 5 and 8 mm of depth for spheroids treated with more than 5 µg/mL ICG (p < 0.05). The fluorescence intensity positively correlated with the size of spheroids (p < 0.01), while the correlation with depth in the tissue-like phantom was strongly negative (p < 0.001). This multicellular spheroid model embedded in a tissue-like phantom seems to be a simple and reproducible in vitro tumor model, allowing a comparison of NIR cameras. The ideal configuration seems to be 450 µm FaDu spheroids incubated for 24 hours with 0.05 mg/ml of ICG, ensuring the best stability, toxicity, incorporation and signal intensity.

Tracing the molecular dynamics of living mitochondria under phototherapy via surface-enhanced Raman scattering spectroscopy.

Subcellular mitochondrion has become a target for improving the therapeutic efficiency and reducing side damage to normal cells via a combination of many therapeutic strategies. However, the underlying molecular mechanisms associated with cell death induced by subcellular dysfunction remain unknown or disputed. In this study, we investigated the dynamic molecular changes of living mitochondria upon phototherapy (photothermal therapy plus photodynamic therapy, PTT & PDT) by surface-enhanced Raman scattering spectroscopy (SERS) and intended to disclose the photo-induced cell death route in breast cancer cells (MCF-7) taking into account the mitochondrion. Indocyanine green (ICG), a Food and Drug Administration (FDA)-approved clinic blood-injection near-infrared angiographic contrast agent and a PTT & PDT drug, was used for the evaluation of the phototherapy effect. The results revealed that the content of phenylalanine (Phe) in mitochondria evidently increased during the phototherapy-induced cell death process. Moreover, the phototherapy-induced cell apoptosis was mainly regulated through the DNA structures. We expect that the understanding of mitochondrial molecular stress responses will be helpful for the diagnosis and therapy of cellular processes associated with mitochondria and provide valuable guidance for the further design and development of more effective therapeutic platforms and methods at the sub-cellular level.

Polylysine modified conjugated polymer nanoparticles loaded with the singlet oxygen probe 1,3-diphenylisobenzofuran and the photosensitizer indocyanine green for use in fluorometric sensing and in photodynamic therapy.

Conjugated polymer hybrid nanoparticles (NPs) loaded with both indocyanine green (ICG) and 1,3-diphenylisobenzofuran (DPBF) are described. The NPs are dually functional in that ICG acts as the photosensitizer, and DPBF as a probe for singlet oxygen (1O2 probe). The nanoparticle core consists of the energy donating host poly(9,9-dioctylfluorenyl-2,7-diyl)-co-(2,5-p-xylene) (PFP). The polymer is doped with the energy acceptor DPBF. Ratiometric fluorometric detection of singlet oxygen is accomplished by measurement of fluorescence at wavelengths of 415 and 458 nm. In addition, the shell of the positively charged polymeric nanoparticles was modified, via electrostatic interaction, with negatively charged PDT drugs ICG. The integrated nanoparticles of type ICG-DPBF-PFP display effective photodynamic performance under 808-nm laser irradiation. The 1O2 sensing behaviors of samples are evaluated based on the ratiometric fluorescent responses produced by DPBF and PFP. 1O2 can be fluorimetically sensed with a detection limit of 28 µM. The multifunctional nanoprobes exhibit effortless cellular uptake, superior photodynamic activity and a rapid ratiometric response to 1O2. Graphical abstractSchematic of a dual-functional nanoplatform for photodynamic therapy (PDT) and singlet oxygen (1O2) feedback. It offers a new strategy for self-monitoring photodynamic ablation. FRET: fluorescence resonance energy transfer. Indocyanine green is attached in the shell of nanoparticles, and 1,3-diphenylisobenzofuran is doped into the energy donating host conjugated polymer.

Foetal bovine serum can reduce toxicity of indocyanine green, brilliant blue G and trypan blue in ARPE-19 cellular model that suggests new surgical staining protocols for internal limiting membrane peeling procedure.

BACKGROUND: To investigate and compare the cytotoxicity of indocyanine green (ICG), brilliant blue G (BBG) and trypan blue (TB) using ARPE-19 cells that have been pre-treated/post-treated with balanced salt solution (BSS) or foetal bovine serum (FBS). METHODS: The cultured human retina pigment epithelium ARPE-19 cells were pre-treated/post-treated with BSS or FBS (represent the autologous serum in clinic) in parallel with cells being soaked with various concentrations of ICG, BBG and TB. The cells were then assessed for viability, growth rate, reactive oxygen species (ROS) level, mitochondrial membrane potential (Δψ) and mitochondrial mass as cytotoxic indices. For the FBS pre-treated cells, only ROS was examined. RESULTS: Using the MTT assay, cytotoxicity seemed to appear when the dye concentration was above 2.5 mg/mL for ICG but no cytotoxicity for BBG and TB at the concentrations used. Cell growth was arrested at a concentration 1 mg/mL when ICG or BBG were present but no arrest at any of the tested concentrations was found for TB with the cell-growth curve was slowest for ICG. Cellular ROS levels increased at all concentrations of all dyes, but the increasing slopes were decreased after FBS post-treatment washout. CONCLUSIONS: As a rinse buffer FBS performs much better than BSS in terms of cell rescue, which agrees with a clinical report when autologous whole blood was applied to macular hole surgery. However, FBS pre-treatment seems to be much better than FBS use as washout buffer in post-treatment.

Ultrahigh Sensitivity Multifunctional Nanoprobe for the Detection of Hydroxyl Radical and Evaluation of Heavy Metal Induced Oxidative Stress in Live Hepatocyte.

Hydroxyl radical (•OH) is an important marker of the progress of heavy metal induced oxidative stress. However, most reported probes and detection methods cannot meet the need of monitoring the •OH concentration within the whole progress because of the limited linear range. Besides, a low detection limit, high sensitivity, and good selectivity were also required. In this study, an ultrahigh sensitivity multifunctional nanoprobe (ICG-modified NaLuF4:Yb,Er) was developed to evaluate heavy metal induced oxidative stress by detecting •OH concentration, with a colorimetric, upconversion luminescence, and photothermal stepped method. This method has a broad linear detection range, from 16 pM to 2 µM, and a low detection limit of 4 pM. Besides, the nanoprobe showed less response to ions, amino acids, biomolecules, and other radical oxygen species (H2O2 and O2-) than •OH. This highly selective, highly sensitive probe with a broad linear detection range has great potential utility for monitoring •OH concentration in live hypatocyte within the progress of heavy metal induced oxidative stress, with probable in vivo applications in the future.

Nonclinical Profile of BLZ-100, a Tumor-Targeting Fluorescent Imaging Agent.

BLZ-100 is a single intravenous use, fluorescent imaging agent that labels tumor tissue to enable more complete and precise surgical resection. It is composed of a chlorotoxin peptide covalently bound to the near-infrared fluorophore indocyanine green. BLZ-100 is in clinical development for intraoperative visualization of human tumors. The nonclinical safety and pharmacokinetic (PK) profile of BLZ-100 was evaluated in mice, rats, canines, and nonhuman primates (NHP). Single bolus intravenous administration of BLZ-100 was well tolerated, and no adverse changes were observed in cardiovascular safety pharmacology, PK, and toxicology studies in rats and NHP. The single-dose no-observed-adverse-effect-levels (NOAELs) were 7 mg (28 mg/kg) in rats and 60 mg (20 mg/kg) in NHP, corresponding to peak concentration values of 89 400 and 436 000 ng/mL and area-under-the-curve exposure values of 130 000 and 1 240 000 h·ng/mL, respectively. Based on a human imaging dose of 3 mg, dose safety margins are >100 for rat and monkey. BLZ-100 produced hypersensitivity reactions in canine imaging studies (lethargy, pruritus, swollen muzzle, etc). The severity of the reactions was not dose related. In a follow-up study in dogs, plasma histamine concentrations were increased 5 to 60 minutes after BLZ-100 injection; this coincided with signs of hypersensitivity, supporting the conclusion that the reactions were histamine based. Hypersensitivity reactions were not observed in other species or in BLZ-100 human clinical studies conducted to date. The combined imaging, safety pharmacology, PK, and toxicology studies contributed to an extensive initial nonclinical profile for BLZ-100, supporting first-in-human clinical trials.

Indocyanine Green: Historical Context, Current Applications, and Future Considerations.

BACKGROUND: Indocyanine green (ICG) is a dye used in medicine since the mid-1950s for a variety of applications in in cardiology, ophthalmology, and neurosurgery; however, its fluorescent properties have only recently been used in the intraoperative evaluation of tissue perfusion. METHOD: A literature review was conducted on the characterization and employment of ICG within the medical field. Historical and current context of ICG was examined while also considering implications for its future use. RESULTS: ICG is a relatively nontoxic, unstable compound bound by albumin in the intravascular space until rapid clearance by the liver. It has widespread uses in hepatic, cardiac, and ophthalmologic studies, and its use in analyzing tissue perfusion and identifying sentinel lymph nodes in cancer staging is gaining popularity. CONCLUSIONS: ICG has myriad applications and poses low risk to the patient. Its historical uses have contributed to medical knowledge, and it is now undergoing investigation for quantifying tissue perfusion, providing targeted therapies, and intraoperative identification of neurovascular anatomy, ophthalmic structures, and sentinel lymph nodes. New applications of ICG may lead to reduction in postoperative wound-related complications, more effective ophthalmologic procedures, and better detection and treatment of cancer cells.

The effects of vital dyes on retinal pigment epithelium cells in oxidative stress.

PURPOSE: To determine the effect of the most commonly used vital dyes in vitrectomy [trypan blue at 0.15% concentration and indocyanine green (ICG) at 0.5% concentration] on the viability of human retinal pigment epithelium (RPE) cell lines (ARPE-19) exposed to oxidative stress. METHODS: ARPE-19 cells unexposed or exposed to oxidative stress (hypoxic chamber) were treated for 1 min with one of the dyes. RPE proliferation was measured by (3)H-thymidine incorporation, adhesion by ability to adhere to fibronectin, and safety by annexin V staining. RESULTS: Proliferation: The dyes affected the proliferation of RPE cells differently under non-hypoxic and hypoxic conditions (p = 0.001). In non-hypoxic conditions, there was no statistically significant difference between the proliferation of the treated (both dyes) and untreated RPE cells (p = 0.279). Under hypoxia, both dyes significantly suppressed proliferation, more so with ICG (p = 0.001). Adhesion: The dyes affected adhesion differently under non-hypoxic and hypoxic conditions (p = 0.04). In non-hypoxic conditions, both increased the adhesive properties of RPE cells to fibronectin, ICG more than trypan blue (p = 0.001). Under hypoxia, both dyes suppressed adhesion, with no statistically significant difference between treated and non-treated RPE cells. Apoptosis: Both dyes increased early apoptosis of RPE cells compared with no treatment (p = 0.001), ICG more than trypan blue. Hypoxia increased the apoptosis of both dyes compared to non-hypoxic conditions (p = 0.02). CONCLUSIONS: In hypoxic conditions, both dyes showed an inhibition of RPE adhesion to fibronectin and proliferation capacity and an increase in early apoptosis compared with non-hypoxic conditions. Apoptosis was greater in ICG-treated RPE cells than in trypan blue-treated cells.

The retinal biocompatibility of dyes in the ex vivo model of the isolated superfused vertebrate retina.

BACKGROUND: Peeling of the internal limiting membrane or epiretinal membranes is a successful principle in macular surgery to achieve a functional benefit. Different dyes are used to facilitate the identification of intraocular tissues. The aim of our work was to investigate the retinal tolerance to the different dyes and their solvent carriers to provide valuable data for surgeons in handling for an optimal intraoperative use. METHODS: Using the ex vivo model of the isolated superfused vertebrate retina technique, the effects of the dyes were tested on human and bovine retinal function. The retinas were perfused with an oxygen preequilibrated standard solution. The electroretinogram (ERG) was recorded using Ag/AgCl electrodes. After recording stable ERG amplitudes, the dyes brilliant blue G, indocyanine green, trypan blue, patent blue, triamcinolone and their solvent carriers were investigated. RESULTS: Reductions of the ERG amplitudes were found for each tested dye. The effects after application of the dyes were dependent on time and concentration of the applied dyes, which were different for each dye. CONCLUSION: In part, the ERG has shown strong effects already after a short period of dye application. Surgeons who rely on the intraocular use of the dyes should keep in mind our findings, and the use of some dyes should be limited to selected cases. The well-considered use of the dyes by the surgeons could lead to a better functional outcome and avoid a possible harmful outcome of the surgery after mishandling.

Comparative study of the optical and heat generation properties of IR820 and indocyanine green.

AbstractNear-infrared (NIR) fluorophores are the focus of extensive research for combined molecular imaging and hyperthermia. In this study, we showed that the cyanine dye IR820 has optical and thermal generation properties similar to those of indocyanine green (ICG) but with improved in vitro and in vivo stability. The fluorescent emission of IR820 has a lower quantum yield than ICG but less dependence of the emission peak location on concentration. IR820 demonstrated degradation half-times approximately double those of ICG under all temperature and light conditions in aqueous solution. In hyperthermia applications, IR820 generated lower peak temperatures than ICG (4-9%) after 3-minute laser exposure. However, there was no significant difference in hyperthermia cytotoxicity, with both dyes causing significant cell growth inhibition at concentrations ≥ 5 µM. Fluorescent images of cells with 10 µM IR820 were similar to ICG images. In rats, IR820 resulted in a significantly more intense fluorescence signal and significantly higher organ dye content than for ICG 24 hours after intravenous dye administration (p < .05). Our study shows that IR820 is a feasible agent in experimental models of imaging and hyperthermia and could be an alternative to ICG when greater stability, longer image collection times, or more predictable peak locations are desirable.

Tempol protects against intravitreous indocyanine green-induced retinal damage in rats.

PURPOSE: Indocyanine green (ICG) has been widely used as a vital dye for macular surgery. However, ICG can be toxic to retinal cells. Here we evaluate whether tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a free radical scavenger, can protect against ICG-induced retinal damage in rats. METHODS: Brown Norway rats received intravitreal injections of ICG 0.5 % or BSS as controls. Tempol (20 mg/kg BW) or PBS as a control was administered intraperitoneally 24 h and 30 min before ICG and once daily for 7 consecutive days. Tempol was detected in the retina using electron paramagnetic resonance (EPR) spectroscopy. One week after ICG injections, the effects of tempol on retinal toxicity were assessed by retinal ganglion cell (RGC) back-labeling and by light microscopy. Electroretinography (ERG) was performed after 1 and 2 weeks. RESULTS: ICG administration reduced RGC numbers by 17 % (1,943 ± 45 vs. 2,342 ± 31 RGCs/mm(2)). Tempol treatment rescued RGCs in a significant manner (2,258 ± 36, p < 0.01) and diminished morphological changes detected by light microscopy. ICG-injected eyes showed a significant reduction of ERG potentials only in PBS-treated animals (V(max) 530 ± 145 µV vs. 779 ± 179 µV, p = 0.0052), but not in the tempol-treated group. CONCLUSIONS: Tempol significantly attenuates ICG-induced toxicity in rat retinas and may therefore be considered for further evaluation as accompanying treatment in ICG-assisted chromovitrectomy.

Toxicity profiles of subretinal indocyanine green, Brilliant Blue G, and triamcinolone acetonide: a comparative study.

BACKGROUND: This study introduces a novel porcine model to examine the histopathological and electrophysiological consequences of retinotoxicity exerted by dyes commonly used for internal limiting membrane (ILM) staining. METHODS: Indocyanine green (ICG) 0.5 mg/ml, Brilliant Blue G (BBG) 0.25 mg/ml and triamcinolone acetonide (TA) 13 mg/ml was injected subretinally in 12 vitrectomized pig eyes. At 6 weeks, retinas were examined by multifocal electroretinography (mfERG), ophthalmoscopy, fluorescein angiograpy, histopathology, and apoptosis assay. RESULTS: mfERG responses were significantly lower in ICG-injected eyes than in healthy fellow eyes (p = 0.039). The ratio between injected eyes and healthy fellow eyes was lower in the ICG group than in the BBG (p = 0.009) and TA group (p = 0.025). No difference between BBG and TA existed. All retinas were reattached, and fluorescein angiographies showed a window defect corresponding to the injected areas but no blood-retina barrier break-down. Histopathology confirmed damage to the outer retina after ICG, but not after BBG and TA. No apoptosis was found at 6 weeks. CONCLUSIONS: Subretinal ICG induces histological and functional damage to the retina, suggesting that ICG should be used with caution in macular hole surgery, where subretinal migration can occur. In contrast, BBG and TA appear safe after subretinal injection.

Synthesis, staining properties, and biocompatibility of a new cyanine dye for ILM peeling.

BACKGROUND: The aim of this work is to investigate the biocompatibility and staining properties of DSS: 3,3'-Di-(4-sulfobutyl)-1,1,1',1'-tetramethyl-di-1H-benz[e]indocarbocyanine (DSS). METHODS: Dye concentrations of 0.5, 0.25, and 0.1% were evaluated (290 and 295 mOsm). Toxicity was assessed using a colorimetric test measuring the inhibition of ARPE 19 cell, human primary RPE cell, and human Müller cell proliferation. Exposure time was 30, 60, 120, and 300 s. Indocyanine green (ICG) (0.5, 0.25, and 0.1%) served as a control. Cells were also illuminated with plain white light (750 mW/cm(2)) for 10 min to assess phototoxic effects. Besides staining of porcine and human lens capsule, internal limiting membrane (ILM)-staining was assessed by applying 0.25 and 0.5% DSS over the macula in two human post-mortem eyes. RESULTS: DSS of 0.25 and 0.1% showed no toxic effect on primary RPE cells and MIO-M1cells, and 0.5, 0.25, and 0.1% for ARPE-19 cells. In MIO-M1cells, 0.5% dye showed a significant reduction of mitochondrial dehydrogenase activity only following an exposure time of 300 s. Following illumination, ICG showed a significantly more pronounced effect on cell viability in primary RPE cells and MIO-M1cells compared to DSS. The absorption maximum is found at 591 nm; the even more bathochromic fluorescence proceeds with a common Stokes' shift where maxima at 620 and 660 nm with a quantum yield of 32% were found. The fluorescence is sufficiently hypsochromic and the fluorescence quantum yield high enough for an easy visual detection. The contrast and staining properties at the ILM were excellent and allowed for a controlled removal of the ILM during surgery. No penetration into deeper retinal layers was noted. CONCLUSIONS: Our results indicate that this new cyanine dye DSS may represent an alternative for ILM staining due to its matched absorption concerning visibility and fluorescence qualities as well as its good biocompatibility.

Comparative in vitro safety analysis of dyes for chromovitrectomy: indocyanine green, brilliant blue green, bromophenol blue, and infracyanine green.

PURPOSE: Vital dyes such as infracyanine green (IfCG), brilliant blue green (BBG), and bromophenol blue (BPB) have been used as an alternative to indocyanine green (ICG) during chromovitrectomy. We compared the in vitro toxicity of IfCG, BBG, and BPB with ICG on the retinal pigment epithelial cells and retinal ganglion cells at various concentrations to optimize the safe dose and duration of exposure. METHODS: Cultured retinal ganglion cells (RGC-5) and human retinal pigment epithelial cells (ARPE-19) were exposed to 2 concentrations (0.25 and 0.5 mg/mL) of ICG, IfCG, BBG, and BPB at various time intervals (1, 5, 15, and 30 minutes). Cell viability was quantified with neutral red assay, and mode of cell death was evaluated with flow cytometry-based Annexin V and propidium iodide staining. RESULTS: Exposure to ICG resulted in 48%-74% reduction in neutral red uptake in both RGC-5 and ARPE-19 cells, after an exposure time of ≥5 minutes compared with control (P < 0.001). Infracyanine green, BBG, and BPB were significantly less toxic on the 2 cell lines at exposure times <15 minutes. (Reduction in cell viability ranged from 6.9% ± 3.3% to 29.3% ± 7.4% when compared with control, P > 0.5.) However, among the newer dyes, BBG caused necrosis in retinal pigment epithelial cells and retinal ganglion cells as the exposure time period increased beyond 5 minutes. CONCLUSION: Newer vital dyes, IfCG, BBG, and BPB, are significantly less toxic on retinal ganglion cells and retinal pigment epithelial cells' cell lines when compared with ICG. Infracyanine green was least toxic among the three newer dyes studied.

A mitochondrial-metabolism-regulatable carrier-free nanodrug to amplify the sensitivity of photothermal therapy.

The oxidative phosphorylation inhibitor atovaquone (ATO) and the photosensitizer new indocyanine green (IR820) were self-assembled into carrier-free nanodrugs (IR820/ATO NPs) to achieve superior photothermal therapy (PTT), offering an attractive mitochondrial metabolism-regulatable approach for breast cancer treatment, where adenosine triphosphate (ATP) was downregulated along with downregulating the expression of heat shock proteins (HSPs) to amplify the sensitivity of PTT.

Bioresponsive Nanoarchitectonics-Integrated Microneedles for Amplified Chemo-Photodynamic Therapy against Acne Vulgaris.

The excessive colonization of Propionibacterium acnes (P. acnes) is responsible for the genesis of acne vulgaris, a common inflammatory disease of skin. However, the conventional anti-acne therapies are always limited by various side effects, drug resistance, and poor skin permeability. Microneedles (MNs) are emerging topical drug delivery systems capable of noninvasively breaking through the skin stratum corneum barrier to efficiently enhance the transdermal drug penetration. Herein, MNs loaded with intelligent pH-sensitive nanoplatforms were constructed for amplified chemo-photodynamic therapy against acne vulgaris, jointly exerting antimicrobial and anti-inflammatory effects. The photosensitizer indocyanine green (ICG) was loaded into the zeolitic imidazolate framework-8 (ZIF-8) to improve its photostability, which would be triggered by 808 nm laser irradiation to generate cytotoxic reactive oxygen species (ROS) to result in oxidative damage and disturbed metabolic activities of P. acnes. In addition to the efficient drug delivery, the ZIF-8 carrier could selectively degrade in response to the acidic microenvironment of acne lesions, and the released Zn2+ also exhibited a potent antimicrobial activity. The fabricated ZIF-8-ICG@MNs presented an outstanding synergistic anti-acne efficiency both in vitro and in vivo. This bioresponsive microneedle patch is expected to be readily adapted as a generalized, modular strategy for noninvasive therapeutics delivery against superficial skin diseases.

Glucose-Targeted Hydroxyapatite/Indocyanine Green Hybrid Nanoparticles for Collaborative Tumor Therapy.

Nanoscale hydroxyapatite (nHA) is considered as a promising drug carrier or therapeutic agent against malignant tumors. But the strong agglomeration tendency and lack of active groups seriously hamper their usage in vivo. To address these issues, we fabricated an organic-inorganic hybrid nanosystem composed of poly(acrylic acid) (PAA), nHA, and indocyanine green (ICG), and further modified with glucose to give a targeting nanosystem (GA@HAP/ICG-NPs). These hybrid nanoparticles (∼90 nm) showed excellent storage and physiological stability assisted by PAA and had a sustained drug release in an acidic tumor environment. In vitro cell experiments confirmed that glucose-attached particles significantly promoted cellular uptake and increased intracellular ICG and Ca2+ concentrations by glucose transporter 1 (GLUT1)-mediated endocytosis. Subsequently, the excessive Ca2+ induced cell or organelle damage and ICG triggered photothermal and photodynamic effects (PTT/PDT) under laser irradiation, resulting in enhanced cell toxicity and apoptosis. In vivo tests revealed that the hybrid nanosystem possessed good hemocompatibility and biosafety, facilitating in vivo circulation and usage. NIR imaging further showed that tumor tissues had more drug accumulation, resulting in the highest tumor growth inhibition (87.89%). Overall, the glucose-targeted hybrid nanosystem was an effective platform for collaborative therapy and expected to be further used in clinical trials.

Safety testing of indocyanine green with different surgical light sources and the protective effect of optical filters.

PURPOSE: The purpose of this study was to assess the light-induced cytotoxicity of indocyanine green (ICG) using different light sources commonly used in macular surgery and to assess the effect of optical filters. METHODS: Primary cultures of porcine retinal pigment epithelium cells were incubated with 0.5 mg/mL ICG solution dissolved in 5% glucose and illuminated with a surgical light fiber for 3 or 15 minutes. Halogen, mercury vapor, xenon, and metal halide light sources were used. Cell viability was assessed using the MTT assay. Retinal pigment epithelium cells without illumination served as controls. The decomposition of ICG after illumination was analyzed by high-performance liquid chromatography. RESULTS: Illumination of retinal pigment epithelium cells with all light sources with or without previous incubation with ICG did not affect cell viability compared with controls. Cell viability was significantly reduced when the cells were not rinsed immediately after incubation. The cytotoxic effect was abolished by a 475-nm long-pass filter. The high-performance liquid chromatography analysis of the illuminated ICG solution identified six cytotoxic ICG decomposition products. CONCLUSION: Optical filters that narrow the emission spectrum of the light sources reduce the light-induced cytotoxicity of ICG. Optical filters applied in ICG-assisted macular surgery may reduce the risk of intraoperative cell damage.

Functional and structural effect of intravitreal indocyanine green, triamcinolone acetonide, trypan blue, and brilliant blue g on rat retina.

PURPOSE: The purpose of this study was to evaluate the functional and structural damage of the retina after intravitreal injections of four different dyes in the rat. METHODS: Rats were injected intravitreally with indocyanine green (ICG), trypan blue, triamcinolone acetonide, or brilliant blue G in the right eye. The other eye was injected with saline and served as a control. Simultaneous bilateral electroretinograms were recorded before injection and 7 and 28 days after injection. Histology and immunohistochemistry analyses with antibodies recognizing glial fibrillary acidic protein and protein kinase C were performed 28 days after the initial injection on both eyes. RESULTS: Seven days after dye injection, the electroretinogram response of the treated eyes was altered in each group. At 1 month, eyes injected with triamcinolone acetonide, trypan blue, or brilliant blue G fully recovered, whereas eyes treated with ICG had A-wave and B-wave reduction of 65% and 63%, respectively. The inner nuclear layer thickness was statistically decreased in the ICG group (P = 0.003) but not with other dyes. Protein kinase C staining was decreased in the ICG group only, but no abnormal qualitative staining was found with either glial fibrillary acidic protein or protein kinase C antibodies with any dye. CONCLUSION: Among the four tested dyes, only ICG led to functional and structural retinal damage.