Photothermal and photodynamic therapy of tumors with plasmonic nanoparticles: challenges and prospects

Cancer remains one of the leading causes of death in the world. For a number of neo-plasms, the efficiency of conventional chemo-and radiation therapies is insufficient because of drug resistance and marked toxicity. Plasmonic photothermal therapy (PPT) using local hyperthermia induced by gold nanoparticles (AuNPs) has recently been extensively explored in tumor treatment. However, despite attractive promises, the current PPT status is limited by laboratory experiments, academic papers, and only a few preclinical studies. Unfortunately, most nanoformulations still share a similar fate: great laboratory promises and fair preclinical trials. This review discusses the current challenges and prospects of plasmonic nanomedicine based on PPT and photodynamic therapy (PDT). We start with consideration of the fundamental principles underlying plasmonic properties of AuNPs to tune their plasmon resonance for the desired NIR-I, NIR-2, and SWIR optical windows. The basic principles for simulation of optical cross-sections and plasmonic heating under CW and pulsed irradiation are discussed. Then, we consider the state-of-the-art methods for wet chemical synthesis of the most popular PPPT AuNPs such as silica/gold nanoshells, Au nanostars, nanorods, and nanocages. The photothermal efficiencies of these nanoparticles are compared, and their applications to current nanomedicine are shortly discussed. In a separate section, we discuss the fabrication of gold and other nanoparticles by the pulsed laser ablation in liquid method. The second part of the review is devoted to our recent experimental results on laser-activated interaction of AuNPs with tumor and healthy tissues and current achievements of other research groups in this application area. The unresolved issues of PPT are the significant accumulation of AuNPs in the organs of the mononuclear phagocyte system, causing potential toxic effects of nanoparticles, and the possibility of tumor recurrence due to the presence of survived tumor cells. The prospective ways of solving these problems are discussed, including developing combined antitumor therapy based on combined PPT and PDT. In the conclusion section, we summarize the most urgent needs of current PPT-based nanomedicine

The assessment of effectiveness of plasmonic resonance photothermal therapy in tumor-bearing rats after multiple intravenous administration of gold nanorods

To assess the effectiveness of plasmonic photothermal therapy (PPT) multiple intravenous strategy of gold nanorods (GNRs) administration was used before laser exposure. The model of alveolar liver cancer PC-1 was used in male outbred albino rats, which were intravenously administrated by single and multiple injections of GNRs and then were treated by PPT. The gold dosage was 400 μg (single injection group), 800 μg (double injection group), 1200 μg (triple injection group), and absorption maximum of gold nanorods suspension was at the wavelength of 808 nm. 24 hours after last injection the tumors were irradiated by the 808-nm diode laser during 15 min at power density 2.3 W/cm2. Temperature control of the tumor heating was provided by IR imager. 24 hours after the PPT the half of animals from each group was withdrawn from the experiments and the sampling tumor tissue for morphological study was performed. In survived animals the growth of tumors was evaluated during 21 days after the PPT. The antitumor effects of PPT after triple intravenous injection were comparable with those obtained at direct intratumoral administration of similar total dose of GNRs. The effectiveness of PPT depended on gold accumulation in tumor, probably, due to sufficient vascularizTation of tumor tissue

The morphological changes in transplanted tumors of rats at plasmonic photothermal therapy

The aim of work was to study the morphological changes in transplanted liver tumors of rats after plasmonic photothermal therapy (PPTT). The gold nanorods functionalized with thiolated polyethylene glycol were injected intravenously to rats with transplanted liver cancer PC-1. A day after injection the tumors were irradiated by the infrared 808-nm diode laser. The withdrawal of the animals from the experiment and sampling of tumor tissue for morphological study were performed 24 hours after the laser exposure. The standard histological and immunohistochemical staining with antibodies to proliferation marker Ki-67 and apoptosis marker BAX were used for morphological study of transplanted tumors. The plasmonic photothermal therapy had pronounced damaging effect in rats with transplanted liver tumors expressed in degenerative and necrotic changes in the tumor cells. The decrease of proliferation marker Ki-67 and increase of expression of apoptosis marker BAX were observed in tumor cells after PPTT

The inflammation markers in serum of tumor-bearing rats after plasmonic photothermal therapy

We report on plasmonic photothermal therapy of rats with inoculated cholangiocarcinoma through the intratumoral injection of PEG-coated gold nanorods followed by CW laser light irradiation. The length and diameter of gold nanorods were 41±8 nm and 10±2 nm, respectively; the particle mass-volume concentration was 400 μg/mL, which corresponds to the optical density of 20 at the wavelength 808 nm. The tumor-bearing rats were randomly divided into three groups: (1) without any treatment (control); (2) with only laser irradiation of tumor; (3) with intratumoral administration of gold nanorods and laser irradiation of tumors. An hour before laser irradiation, the animals were injected intratumorally with gold nanorod solutions in the amount of 30% of the tumor volume. The infrared 808-nm laser with power density of 2.3 W/cm2 was used for plasmonic photothermal therapy (PTT). The withdraw of animals from the experiment was performed 24 h after laser exposure. The content of lipid peroxidation products and molecular markers of inflammation (TNF-α, IGF-1, VEGF-C) was determined by ELISA test in serum of rats. The standard histological techniques with hematoxylin and eosin staining were used for morphological examination of tumor tissues. It was revealed that the significant necrotic changes were noted in tumor tissue after plasmonic photothermal therapy, which were accompanied by formation of inflammatory reaction with release of proinflammatory cytokines and lipid peroxidation products into the bloodstream

The effects of prolonged oral administration of gold nanoparticles on the morphology of hematopoietic and lymphoid organs

Currently, the usage of gold nanoparticles as photosensitizers and immunomodulators for plasmonic photothermal therapy has attracted a great attention of researches and end-users. In our work, the influence of prolonged peroral administration of gold nanoparticles (GNPs) with different sizes on the morphological changes of hematopoietic and lymphoid organs was investigated. The 24 white outbred male rats weighing 180-220 g were randomly divided into groups and administered orally for 30 days the suspension of gold nanospheres with diameters of 2, 15 and 50 nm at a dosage of 190 μg/kg of animal body weight. To prevent GNPs aggregation in a tissue and enhance biocompatibility, they were functionalized with thiolated polyethylene glycol. The withdrawal of the animals from the experiment and sampling of spleen, lymph nodes and bone marrow tissues for morphological study were performed a day after the last administration. In the spleen the boundary between the red and white pulp was not clearly differ in all experimental groups, lymphoid follicles were significantly increased in size, containing bright germinative centers represented by large blast cells. The stimulation of lymphocyte and myelocytic series of hematopoiesis was recorded at morphological study of the bone marrow. The number of immunoblasts and large lymphocytes was increased in all structural zones of lymph nodes. The more pronounced changes were found in the group with administration of 15 nm nanoparticles. Thus, the morphological changes of cellular components of hematopoietic organs have size-dependent character and indicate the activation of the migration, proliferation and differentiation of immune cells after prolonged oral administration of GNPs

High-efficiency freezing-induced loading of inorganic nanoparticles and proteins into micron- and submicron-sized porous particles

We demonstrate a novel approach to the controlled loading of inorganic nanoparticles and proteins into submicron- and micron-sized porous particles. The approach is based on freezing/thawing cycles, which lead to high loading densities. The process was tested for the inclusion of Au, magnetite nanoparticles, and bovine serum albumin in biocompatible vaterite carriers of micron and submicron sizes. The amounts of loaded nanoparticles or substances were adjusted by the number of freezing/thawing cycles. Our method afforded at least a three times higher loading of magnetite nanoparticles and a four times higher loading of protein for micron vaterite particles, in comparison with conventional methods such as adsorption and coprecipitation. The capsules loaded with magnetite nanoparticles by the freezing-induced loading method moved faster in a magnetic field gradient than did the capsules loaded by adsorption or coprecipitation. Our approach allows the preparation of multicomponent nanocomposite materials with designed properties such as remote control (e.g. via the application of an electromagnetic or acoustic field) and cargo unloading. Such materials could be used as multimodal contrast agents, drug delivery systems, and sensors

Advantages of Highly Spherical Gold Nanoparticles as Labels for Lateral Flow Immunoassay

The use of lateral flow immunoassays (LFIAs) for rapid on-site testing is restricted by their relatively high limit of detection (LoD). One possible way to decrease the LoD is to optimize nanoparticle properties that are used as labels. We compare two types of Au nanoparticles: usual quasispherical gold nanoparticles (C-GNPs), obtained by the Turkevich–Frens method, and superspherical gold nanoparticles (S-GNPs), obtained by a progressive overgrowth technique. Average diameters were 18.6–47.5 nm for C-GNPs and 20.2–90.4 nm for S-GNPs. Cardiomarker troponin I was considered as the target analyte. Adsorption and covalent conjugation with antibodies were tested for both GNP types. For C-GNPs, the minimal LoD was obtained with 33.7 nm nanoparticles, reaching 12.7 ng/mL for covalent immobilization and 9.9 ng/mL for adsorption. The average diameter of S-GNPs varied from 20.2 to 64.5 nm, which resulted in a decrease in LoD for an LFIA of troponin I from 3.4 to 1.2 ng/mL for covalent immobilization and from 2.9 to 2.0 ng/mL for adsorption. Thus, we obtained an 8-fold decrease in LoD (9.9 to 1.2 ng/mL) by using S-GNPs. This effect can be related to more effective antibody immobilization and improved S-GNP optical properties. The obtained results can improve LFIAs for various practically significant analytes

Lateral Flow Immunoassay of SARS-CoV-2 Antigen with SERS-Based Registration: Development and Comparison with Traditional Immunoassays

The current COVID-19 pandemic has increased the demand for pathogen detection methods that combine low detection limits with rapid results. Despite the significant progress in methods and devices for nucleic acid amplification, immunochemical methods are still preferred for mass testing without specialized laboratories and highly qualified personnel. The most widely used immunoassays are microplate enzyme-linked immunosorbent assay (ELISA) with photometric detection and lateral flow immunoassay (LFIA) with visual results assessment. However, the disadvantage of ELISA is its considerable duration, and that of LFIA is its low sensitivity. In this study, the modified LFIA of a specific antigen of the causative agent of COVID-19, spike receptor-binding domain, was developed and characterized. This modified LFIA includes the use of gold nanoparticles with immobilized antibodies and 4-mercaptobenzoic acid as surface-enhanced Raman scattering (SERS) nanotag and registration of the nanotag binding by SERS spectrometry. To enhance the sensitivity of LFIA-SERS analysis, we determined the optimal compositions of SERS nanotags and membranes used in LFIA. For benchmark comparison, ELISA and conventional colorimetric LFIA were used with the same immune reagents. The proposed method combines a low detection limit of 0.1 ng/mL (at 0.4 ng/mL for ELISA and 1 ng/mL for qualitative LFIA) with a short assay time equal to 20 min (at 3.5 h for ELISA and 15 min for LFIA). The results obtained demonstrate the promise of using the SERS effects in membrane immuno-analytical systems

The assessment of effectiveness of plasmonic resonance photothermal therapy in tumor-bearing rats after multiple intravenous administration of gold nanorods

To assess the effectiveness of plasmonic photothermal therapy (PPT) multiple intravenous strategy of gold nanorods (GNRs) administration was used before laser exposure. The model of alveolar liver cancer PC-1 was used in male outbred albino rats, which were intravenously administrated by single and multiple injections of GNRs and then were treated by PPT. The gold dosage was 400 μg (single injection group), 800 μg (double injection group), 1200 μg (triple injection group), and absorption maximum of gold nanorods suspension was at the wavelength of 808 nm. 24 hours after last injection the tumors were irradiated by the 808-nm diode laser during 15 min at power density 2.3 W/cm2. Temperature control of the tumor heating was provided by IR imager. 24 hours after the PPT the half of animals from each group was withdrawn from the experiments and the sampling tumor tissue for morphological study was performed. In survived animals the growth of tumors was evaluated during 21 days after the PPT. The antitumor effects of PPT after triple intravenous injection were comparable with those obtained at direct intratumoral administration of similar total dose of GNRs. The effectiveness of PPT depended on gold accumulation in tumor, probably, due to sufficient vascularizTation of tumor tissue

Plasmonic photothermal therapy: Approaches to advanced strategy

BACKGROUND: The analysis of recent studies on plasmonic photothermal therapy (PPT) after intravenous administration of gold nanorods (GNRs) has demonstrated that the effectiveness of nanoparticle-assisted laser hyperthermia depends on a correct dosage strategy of nanoparticle administration. Accumulation of GNRs in tumor tissue dramatically increases the local heating of the tumor without damage to healthy tissues. However, the optimal doses of GNR intravenous injections (IVIs) for effective accumulation in tumors, and optimal protocols of PPT are not designed yet. The current study aims to improve the efficacy of PPT in tumor-bearing rats using multiple fractional intravenous administration of GNRs. MATERIALS AND METHODS: For PPT experiments, the GNRs with aspect ratio of 4.1 were functionalized with thiolated polyethylene glycol (PEG) and their suspensions were used for multiple fractional intravenous administration in outbred albino male rats with experimental model of rat liver cancer (cholangiocarcinoma line PC-1). Doppler ultrasonography was performed to characterize the vascularity of transplanted rat tumors before any treatment. After a final injection of GNRs, tumor was irradiated during 15 minutes by 808-nm NIR diode laser at a power density 2.3 W/cm2 . The animals were withdrawn from the experiment and sampling of tissues for morphological study and gold accumulation was performed 24 hours and 3 weeks after PPT. RESULTS: The multiple IVIs of gold nanorods and further PPT of transplanted cholangiocarcinoma provided significant damage to tumor tissue resulting in pronounced necrotic mass and retardation of the tumor growth. More importantly, the proposed PPT protocol had low toxicity as evidenced by histological examination of internal organs. The efficiency of PPT depends on the presence of newly formed vasculature as revealed by the Doppler ultrasound investigation. CONCLUSION: The repeatable IVIs promote greater of GNR accumulation within the tumor thus resulting in higher PPT efficacy. Accompanying ultrasonography can be useful for prognosis and monitoring of treatment. Lasers Surg. Med. 50:1025-1033, 2018. © 2018 Wiley Periodicals, Inc