NIR Light-Activated Drug Release for Synergetic Chemo–Photothermal Therapy

Acidic Lysosome-Anchoring Croconium-Based Nanoplatform for Enhanced Triple-Mode Bioimaging and Fe3+-Triggered Tumor Synergistic Therapy

Metal-modulated croconium dyes with multimodal-imaging and synergistic therapy in the tumor microenvironment have exhibited great potential in tumor theranostics. However, their unideal structure optimization always weakened the efficacy of near-infrared fluorescence-photoacoustic (NIRF/PA) imaging and photothermal therapy (PTT). Here, we screened croconium dye containing two indole groups with better NIRF/PA imaging and PTT in their family, linked to two morpholine rings, and obtained CR-736, as a lysosome-targeting and Fe3+-modulated agent. The established CR-736-Fe3+ nanoplatform was accurately delivered to the breast tumor site, released CR-736 and Fe3+ in the lower acidic lysosome microenvironment, and activated pH-responsive NIRF/PA/magnetic resonance imaging and PTT. Furthermore, ferroptosis generated hydroxyl free radicals and lipid peroxide by consuming GSH and H2O2 by dint of the accumulation of Fe3+ in tumor cells, which resulted in the inhibition of the expression of heat shock proteins and the concomitant recovery of PTT. The synergistic therapy of PTT, ferroptosis, and chemodynamics was further optimized to the maximal extent in tumor lysosome acidic microenvironment and proved both in vitro and a mouse tumor model. This study opens a new avenue in designing excellent and unique croconium-based nanoplatforms, synergizing multiple tumor theranostic methods, and further optimizing the theranostic effects in tumor microenvironment.

Engineered Liposomes in Interventional Theranostics of Solid Tumors

Engineered liposomal nanoparticles have unique characteristics as cargo carriers in cancer care and therapeutics. Liposomal theranostics have shown significant progress in preclinical and clinical cancer models in the past few years. Liposomal hybrid systems have not only been approved by the FDA but have also reached the market level. Nanosized liposomes are clinically proven systems for delivering multiple therapeutic as well as imaging agents to the target sites in (i) cancer theranostics of solid tumors, (ii) image-guided therapeutics, and (iii) combination therapeutic applications. The choice of diagnostics and therapeutics can intervene in the theranostics property of the engineered system. However, integrating imaging and therapeutics probes within lipid self-assembly "liposome" may compromise their overall theranostics performance. On the other hand, liposomal systems suffer from their fragile nature, site-selective tumor targeting, specific biodistribution and premature leakage of loaded cargo molecules before reaching the target site. Various engineering approaches, viz., grafting, conjugation, encapsulations, etc., have been investigated to overcome the aforementioned issues. It has been studied that surface-engineered liposomes demonstrate better tumor selectivity and improved therapeutic activity and retention in cells/or solid tumors. It should be noted that several other parameters like reproducibility, stability, smooth circulation, toxicity of vital organs, patient compliance, etc. must be addressed before using liposomal theranostics agents in solid tumors or clinical models. Herein, we have reviewed the importance and challenges of liposomal medicines in targeted cancer theranostics with their preclinical and clinical progress and a translational overview.

Photothermal Properties of IR-780-Based Nanoparticles Depend on Nanocarrier Design: A Comparative Study on Synthetic Liposomes and Cell Membrane and Hybrid Biomimetic Vesicles

Biomimetic nanoparticles hold great promise for photonic-mediated nanomedicine due to the association of the biological functionality of the membrane with the physical/chemical goals of organic/inorganic structures, but studies involving fluorescent biomimetic vesicles are still scarce. The purpose of this article is to determine how photothermal therapy (PTT) with theranostic IR-780-based nanoparticles depends on the dye content, cholesterol content, lipid bilayer phase and cell membrane type. The photophysical responses of synthetic liposomes, cell membrane vesicles and hybrid nanoparticles are compared. The samples were characterized by nanoparticle tracking analysis, photoluminescence, electron spin resonance, and photothermal- and heat-mediated drug release experiments, among other techniques. The photothermal conversion efficiency (PCE) was determined using Roper's method. All samples excited at 804 nm showed three fluorescence bands, two of them independent of the IR-780 content. Samples with a fluorescence band at around 850 nm showed photobleaching (PBL). Quenching was higher in cell membrane vesicles, while cholesterol inhibited quenching in synthetic liposomes with low dye content. PTT depended on the cell membrane and was more efficient for melanoma than erythrocyte vesicles. Synthetic liposomes containing cholesterol and a high amount of IR-780 presented superior performance in PTT experiments, with a 2.4-fold PCE increase in comparison with free IR-780, no PBL and the ability to heat-trigger doxorubicin release.

Nanoarchitectonics of Indocyanine Green/Doxorubicin-Loaded Hydroxyl Boron Nitride Nanosheets for Chemophotothermal Therapy

Biocompatible hydroxylated boron nitride nanosheets were effectively loaded with indocyanine green and doxorubicin using successive assembly. The indocyanine green/doxorubicin-loaded hydroxyl boron nitride nanosheets (ICG/DOX@OH-BNNS) integrated photothermal therapy and chemotherapy into a single nano vehicle. It had been confirmed that ICG/DOX@OH-BNNS could produce reactive oxygen species and exhibit excellent photothermal effects and light-triggered faster DOX release with NIR laser irradiation. On the other hand, the fluorescence of DOX in ICG/DOX@OH-BNNS was also used for visualizing subcellular location. Compared with individual chemotherapy and photothermal therapy, the combined treatment of ICG/DOX@OH-BNNS could synergistically induce the apoptosis and death of A549 cells and suppress S180 tumor growth in vivo.

A plasmon-enhanced fluorescent gold coated novel lipo-polymeric hybrid nanosystem: synthesis, characterization and application for imaging and photothermal therapy of breast cancer

This study reports a hybrid lipo-polymeric nanosystem (PDPC NPs) synthesized by a modified hydrogel-isolation technique. The ability of the nanosystem to encapsulate hydrophilic and hydrophobic molecules has been demonstrated, and their enhanced cellular uptake has been observed in vitro. The PDPC NPs, surface coated with gold by in situ reduction of chloroauric acid (PDPC-Au NPs), showed a photothermal transduction efficacy of ∼65%. The PDPC-Au NPs demonstrated an increase in intracellular ROS, triggered DNA damage and resulted in apoptotic cell death when tested against breast cancer cells (MCF-7). The disintegration of PDPC-Au NPs into smaller nanoparticles with near-infrared (NIR) laser irradiation was understood using transmission electron microscopy imaging. The lipo-polymeric hybrid nanosystem exhibited plasmon-enhanced fluorescence when loaded with IR780 (a NIR dye), followed by surface coating with gold (PDPC-IR-Au NPs). This paper is one of the first reports on the plasmon-enhanced fluorescence within a nanosystem by simple surface coating of Au, to the best of our knowledge. This plasmon-enhanced fluorescence was unique to the lipo-polymeric hybrid system, as the same was not observed with a liposomal nanosystem. The plasmon-enhanced fluorescence of PDPC-IR-Au NPs, when applied for imaging cancer cells and zebrafish embryos, showed a strong fluorescence signal at minimal concentrations of the dye. The PDPC-IR-Au NPs were also applied for photothermal therapy of breast cancer in vitro and in vivo, and the results depicted significant therapeutic benefits.

Selectively down-regulated PD-L1 by albumin-phenformin nanoparticles mediated mitochondrial dysfunction to stimulate tumor-specific immunological response for enhanced mild-temperature photothermal efficacy

Background

Mild-temperature photothermal therapy (mild-PTT) has emerged as a highly promising antitumor strategy by triggering immunogenic cell death (ICD) to elicit both innate and adaptive immune responses for tumor control. However, mild-PTT still leads to the risk of tumor recurrence or metastasis because it could hardly completely eradicate tumors due to its impaired immunological efficacy owing to the enhanced PD-L1 expression in tumor cells after treatment.

Results

In this study, we described a hydrogen peroxide (H₂O₂) responsive manganese dioxide mineralized albumin nanocomposite loading with mitochondria function inhibitor phenformin (PM) and near-infrared photothermal dye indocyanine green (ICG) by modified two-step biomineralization method. In combination with ICG induced mild-PTT and PM mediated mitochondria dysfunction, PD-L1 expression was obviously down-regulated and the generated immunological responses was able to effectively attack the remaining tumor cells. Meanwhile, the risk of tumor metastasis was effectively inhibited by reducing the expression of tumor invasion-related signal molecules (TGF-β and vimentin) after combining treatment.

Conclusion

Such a strategy offers novel insight into the development of nanomedicine for mild-PTT as well as cancer immunotherapy, which can provide protection against tumor relapse post elimination of their initial and metastatic tumors.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01124-8.

Over-expression of PD-L1 after mild-photothermal therapy significantly limited its efficacy.

Phenformin could effectively downregulate PD-L1 expression and inhibit tumor metastasis through AMPK activation.

Hydrogen peroxide responsive manganese dioxide mineralized albumin nanocomplex co-loading with phenformin and ICG named ICG@PM@NP was constructed by modified two-step biomineralization method.

ICG@PM@NP could enhance T cell infiltration and antitumor metastasis in vivo.

ICG@PM@NP mediated mild-photothermal therapy could make up the defects of conventional mild-photothermal therapy in lacking the anti-metastasis ability and inducing enhanced PD-L1 expression.

Thiophene donor for NIR-II fluorescence imaging-guided photothermal/photodynamic/chemo combination therapy

Organic fluorophores/photosensitizers have been widely used in biological imaging and photodynamic and photothermal combination therapy in the first near-infrared (NIR-I) window. However, their applications in the second near-infrared (NIR-II) window are still limited primarily due to low fluorescence quantum yields (QYs). Here, a boron dipyrromethene (BDP) is created as a molecularly engineered thiophene donor unit with high QYs to the redshift. Thiophene insertion initiates substantial redshifts of the absorbance as compared to its counterparts in which iodine is introduced. The fluorescent molecule can be triggered by an NIR laser with a single wavelength, thereby producing emission in the NIR-II windows. Single NIR laser-triggered phototherapeutic nanoparticles (NPs) are developed by encapsulating the BDP and the chemotherapeutic drug docetaxel (DTX) by using a synthetic amphiphilic poly(styrene-co-chloromethyl styrene)-graft-poly(ethylene glycol) functionalized with folic acid (FA). These BDP-T-N-DTX-FA NPs not only show superior solubility and high singlet oxygen QY (Φ_Δ=62%) but also demonstrate single NIR laser-triggered multifunctional characteristics. After intravenous administration of the NPs into 4T1 tumor-bearing mice, the accumulation of the NPs in the tumor showed a high signal-to-background ratio (11.8). Furthermore, 4T1 tumors in mice were almost eradicated by DTX released from the BDP-T-N-DTX-FA NPs under single NIR laser excitation and the combination of photodynamic therapy (PDT) and photothermic therapy (PTT). STATEMENT OF SIGNIFICANCE: The application of organic photosensitizers is still limited primarily due to low fluorescence quantum yields (QYs) in the second near-infrared (NIR-II) window. Here, a boron dipyrromethene (BDP) as a molecularly engineered thiophene donor unit with high QYs to the redshift is created. Phototherapeutic nanoparticles (NPs) are developed by encapsulating the BDP and docetaxel (DTX) using a synthetic amphiphilic poly(styrene-co-chloromethyl styrene)-graft-poly(ethylene glycol) functionalized with folic acid (FA). These BDP-T-N-DTX-FA NPs not only show high singlet oxygen QY (Φ_Δ=62%) but also demonstrate single NIR laser-triggered multifunctional characteristics and a high signal-to-background ratio (11.8). Furthermore, 4T1 tumors in mice were almost eradicated by DTX released from the BDP-T-N-DTX-FA NPs under single NIR laser excitation and the PDT/PTT combination therapy.

IR780-based nanomaterials for cancer imaging and therapy

IR780, a small molecule with a strong optical property and excellent photoconversion efficiency following near infrared (NIR) irradiation, has attracted increasing attention in the field of cancer treatment and imaging. This review is focused on different IR780-based nanoplatforms and the application of IR780-based nanomaterials for cancer bioimaging and therapy. Thus, this review summarizes the overall aspects of IR780-based nanomaterials that positively impact cancer biomedical applications.

V, John R, Rengan AK. Iontophoresis mediated localized delivery of liposomal gold nanoparticles for photothermal and photodynamic therapy of acne

Iontophoresis mediated localized delivery of drug entrapping liposomal gold nanoparticles for photothermal and photodynamic therapy of acne.

Surface Modification of Liposomes Using IR700 Enables Efficient Controlled Contents Release Triggered by Near-IR Light

Stimuli-responsive liposomes are promising drug carriers for cancer treatment because they enable controlled drug release and the maintenance of desired drug concentrations in tumor tissue. In particular, near-IR (NIR) light is a useful stimulus for triggering drug release from liposomes based on its advantages such as deep tissue penetration and safety. Previously, we found that a silicon phthalocyanine derivative, IR700, conjugated to antibodies, can induce the rupture of the cell membrane following irradiation by NIR light. Based on this finding, we constructed IR700-modified liposomes (IR700 liposomes) and evaluated their drug release properties triggered by NIR light. IR700 liposomes released substantial amounts of encapsulated calcein following irradiation by NIR light. Drug release was substantially suppressed by the addition of sodium azide, suggesting that liposomal membrane permeabilization was mediated by singlet oxygen generated from IR700. Moreover, calcein release from IR700 liposomes triggered by NIR light was promoted under conditions of deoxygenation and the presence of electron donors. Thus, membrane disruption should be induced by the physical change of IR700 from highly hydrophilic to hydrophobic as we previously described, although singlet oxygen can cause a certain level of membrane disruption under normoxia. We also observed that doxorubicin-encapsulated IR700 liposomes exhibited significant cytotoxic effects against CT-26 murine colon carcinoma cells following NIR light exposure. These results indicate that IR700 liposomes can efficiently release anti-cancer drugs following NIR light irradiation even under hypoxic conditions and, therefore, they would be useful for cancer treatment.

Assessing the Combinatorial Chemo-Photothermal Therapy Mediated by Sulfobetaine Methacrylate-Functionalized Nanoparticles in 2D and 3D In Vitro Cancer Models

Combinatorial cancer therapies mediated by nanomaterials can potentially overcome the limitations of conventional treatments. These therapies are generally investigated using 2D in vitro cancer models, leading to an inaccurate screening. Recently, 3D in vitro spheroids have emerged in the preclinical testing stage of nanomedicines due to their ability to mimic key features of the in vivo solid tumors. Investigate the chemo-photothermal therapy mediated by Doxorubicin and IR780 loaded sulfobetaine methacrylate functionalized nanoparticles, for the first time, using monolayers of cancer cells and spheroids. In the 2D cancer models, the nanomaterials' mediated photothermal therapy, chemotherapy, and chemo-photothermal therapy reduced cancer cells' viability to about 58%, 29%, and 1%, respectively. Interestingly, when the nanomaterials' mediated photothermal therapy is tested on 3D spheroids, no cytotoxic effect is noticed. In contrast, the nanostructures' induced chemotherapy decreased spheroids' viability to 42%. On the other hand, nanomaterials' mediated chemo-photothermal therapy diminished spheroids' viability to 16%, being the most promising therapeutic modality. These results demonstrate the importance of using 3D spheroids during the in vitro screening of single/combinatorial therapies mediated by nanomaterials.

Prototypic Heptamethine Cyanine Incorporating Nanomaterials for Cancer Phototheragnostic

Developing technologies that allow the simultaneous diagnosis and treatment of cancer (theragnostic) has been the quest of numerous interdisciplinary research teams. In this context, nanomaterials incorporating prototypic near infrared (NIR)-light responsive heptamethine cyanines have been showing very promising results for cancer theragnostic. The precisely engineered features of these nanomaterials endow them with the ability to achieve a high tumor accumulation, enabling a tumor's visualization by NIR fluorescence and photoacoustic imaging modalities. Upon interaction with NIR light, the tumor-homed heptamethine cyanine-incorporating nanomaterials can also produce a photothermal/photodynamic effect with a high spatio-temporal resolution and minimal side effects, leading to an improved therapeutic outcome. This progress report analyses the application of nanomaterials incorporating prototypic NIR-light responsive heptamethine cyanines (IR775, IR780, IR783, IR797, IR806, IR808, IR820, IR825, IRDye 800CW, and Cypate) for cancer photothermal therapy, photodynamic therapy, and imaging. Overall, the continuous development of nanomaterials incorporating the prototypic NIR absorbing heptamethine cyanines will cement their phototheragnostic capabilities.

ZnO capped flower-like porous carbon-Fe3O4 composite as carrier for bi-triggered drug delivery

In this work, ZnO capped flower-like porous carbon-Fe₃O₄ composite (FPCS-Fe₃O₄-ZnO) was constructed as a carrier for pH and microwave bi-triggered drug delivery. In the composite, the FPCS achieves high-efficiency drug loading, the Fe₃O₄ acts as magnetic targeting agent and microwave absorption enhancer, and the ZnO nanoparticle as a sealing agent in response to pH stimulation. The carrier exhibited a flower-mesoporous sphere of 270 nm, a specific surface area of 101 m²/g, a saturation magnetization of 14.08 emu/g, as well as good microwave thermal conversion properties (The temperature was raised from 25 °C to 60 °C only 24 s). Simultaneously, the carrier achieved an efficient drug loading with a drug loading rate of 99.1%. During the drug release experiments, obvious pH-dependent release behavior was observed, the drug release rate at 12 h was 8.2%, 19.0%, and 56.3% at pH 7.4, 5.0 and 3.0 respectively. Moreover the drug release rate increased from 8.2% to 39.9% after microwave stimulation at pH 7.4. In addition, cytotoxicity tests indicate that the carrier has good biocompatibility. Thus, this multifunctional pH and microwave bi-triggered carrier was expected to be further applied to drug delivery system(DDS).

Multifunctional Theranostic Liposomes Loaded with a Hypoxia-Activated Prodrug for Cascade-Activated Tumor Selective Combination Therapy

Photodynamic therapy (PDT) is becoming a promising therapeutic regimen but is limited by the hypoxic microenvironment in solid tumors and the undesirable post-treatment phototoxicity side effects on normal tissues. To overcome these restrictions and enhance the antitumor therapeutic effect, near-infrared (NIR) light-activated, cancer cell-specific, hypoxia prodrug-loaded chlorin e6 liposomes were developed for tumor selective combination therapy guided by multimodal imaging. The photothermal agent indocyanine green (ICG) and hypoxia-activated prodrug tirapazamine (TPZ) were coencapsulated into the liposomes, followed by modification with cRGD and conjugation with Gd^III to form ICG/TPZ@Ce6-Gd^III theranostic liposomes (ITC-Gd^III TLs). In the ITC-Gd^III TLs, both the fluorescence and photodynamic effect of Ce6 were quenched by ICG via fluorescence resonance energy transfer. The ITC-Gd^III TLs can effectively reach the tumor site through the enhanced permeability and retention effect as well as the cRGD-mediated active targeting ability. The fluorescence and photodynamic effect of Ce6 can be activated by the photothermal effect of ICG under NIR light. Upon subsequent irradiation with a 660 nm laser, the released Ce6 could kill cancer cells by generating cytotoxic singlet oxygen. Furthermore, the PDT process would induce hypoxia, which in turn activated the antitumor activity of the codelivered hypoxia-activated prodrug TPZ for a combination antitumor effect. The TLs could be utilized for multimodal imaging (fluorescence/photoacoustic/magnetic resonance imaging)-guided cascade-activated tumor inhibition with optimized therapeutic efficiency and minimized side effects, holding great potential for constructing intelligent nanotheranostics.

Bifunctional liposomes reduce the chemotherapy resistance of doxorubicin induced by reactive oxygen species

Doxorubicin (DOX) liposome is a widely used nano-medicine for colorectal cancer treatment. However, doxorubicin therapy increases the level of reactive oxygen species (ROS) in tumor cells, such as hydrogen peroxide (H₂O₂), which can stabilize hypoxia-inducible-factor-1α (HIF-1α). In a tumor hypoxic microenvironment, HIF-1 can up-regulate tumor-resistance related proteins, including P-glycoprotein (P-gp), glucose transporter 1 (GLUT-1), and matrix metalloproteinase 9 (MMP-9), leading to tumor tolerance to chemotherapy. The functional inhibition of HIF-1 can overcome this resistance and enhance the efficacy of tumor therapy. Here, we encapsulated one of the most effective HIF-1 inhibitors, acriflavine (ACF), and DOX in liposomes (DOX-ACF@Lipo) to construct bifunctional liposomes. ACF and DOX, released from DOX-ACF@Lipo, could effectively suppress the function of HIF-1 and the process of DNA replication, respectively. Consequently, the bifunctional liposome has great potential to be applied in clinics to overcome chemotherapy resistance induced by hypoxia.

The awesome power of optogenetics in hearing research

The use of light as a tool to manipulate cellular processes or optogenetics has developed rapidly in various biological fields over the past decade. Through the addition of photosensitive proteins, light can be used to control intracellular mechanisms, map neuronal pathways, and alter variables that would be difficult to control using other mechanisms. Photons of a specific wavelength affect these light sensitive targets for in vitro or in vivo experiments. Optogenetics is beneficial because it gives the investigator spatial and temporal control over experimental variables. Precise control is achieved by sequential activation of different ion channels and the ability to non-invasively control membrane potential. In this review, we will discuss the recent use of optogenetics in biological fields to understand the role of different cell types in hearing and creating a new cochlear implant, as well as future uses such as light controlled drug delivery and gene expression.

Drug Diffusion Along an Intact Mammalian Cochlea

Intratympanic drug administration depends on the ability of drugs to pass through the round window membrane (RW) at the base of the cochlea and diffuse from this location to the apex. While the RW permeability for many different drugs can be promoted, passive diffusion along the narrowing spiral of the cochlea is limited. Earlier measurements of the distribution of marker ions, corticosteroids, and antibiotics demonstrated that the concentration of substances applied to the RW was two to three orders of magnitude higher in the base compared to the apex. The measurements, however, involved perforating the cochlear bony wall and, in some cases, sampling perilymph. These manipulations can change the flow rate of perilymph and lead to intake of perilymph through the cochlear aqueduct, thereby disguising concentration gradients of the delivered substances. In this study, the suppressive effect of salicylate on cochlear amplification via block of the outer hair cell (OHC) somatic motility was utilized to assess salicylate diffusion along an intact guinea pig cochlea in vivo. Salicylate solution was applied to the RW and threshold elevation of auditory nerve responses was measured at different times and frequencies after application. Resultant concentrations of salicylate along the cochlea were calculated by fitting the experimental data using a mathematical model of the diffusion and clearing of salicylate in a tube of variable diameter combined with a model describing salicylate action on cochlear amplification. Concentrations reach a steady-state at different times for different cochlear locations and it takes longer to reach the steady-state at more apical locations. Even at the steady-state, the predicted concentration at the apex is negligible. Model predictions for the geometry of the longer human cochlea show even higher differences in the steady-state concentrations of the drugs between cochlear base and apex. Our findings confirm conclusions that achieving therapeutic drug concentrations throughout the entire cochlear duct is hardly possible when the drugs are applied to the RW and are distributed via passive diffusion. Assisted methods of drug delivery are needed to reach a more uniform distribution of drugs along the cochlea.

Near-infrared laser-mediated drug release and antibacterial activity of gold nanorod-sputtered titania nanotubes

The infection control of implants is one of the hot issues in the field of medicine and dentistry. In this study, we prepared gold nanorod–sputtered titania nanotubes on titanium surface, which is the main component of implant material, and aimed to estimate the remote-controlled tetracycline release and resulting antibacterial effects of gold nanorod–sputtered titania nanotubes using near-infrared laser irradiation. Gold nanorods prepared by ion plasma sputtering (aspect ratio = 1:3) showed optical properties like those of chemically synthesized gold nanorods, exhibiting photothermal effects in the near-infrared region, as demonstrated using field-emission scanning electron microscopy, transmission electron microscopy, and diffuse ultraviolet–visible–near-infrared spectrophotometry. In addition, a 2 wt% tetracycline/polycaprolactone mixture was found to be the most suitable experimental group to demonstrate the biological compatibilities and antibacterial activities. The results of antibacterial agar diffusion tests and near-infrared-mediated tetracycline release tests in vivo confirmed that remote-controlled tetracycline elution using near-infrared laser irradiation was highly effective. Therefore, gold nanorod–sputtered titania nanotubes would be expected to enable the continued use of the photothermal therapy of gold nanorods and extend the limited use of titania showing photocatalytic activity only within the ultraviolet-to-near-infrared region.

Near-Infrared Activated Release of Doxorubicin from Plasmon Resonant Liposomes

Precise control of drug release from nanoparticles can improve efficacy and reduce systemic toxicity associated with administration of certain medications. Here, we combined two phenomena, photothermal conversion in plasmon resonant gold coating and thermal sensitivity of liposome compositions, to achieve a drug delivery system that rapidly releases doxorubicin in response to external stimulus.

Methods: Thermosensitive liposomes were loaded with doxorubicin and gold-coated to produce plasmon resonant drug delivery system. Plasmon resonance facilitates release of contents upon near-infrared laser illumination, thus providing spatial and temporal control of the process. This controlled delivery system was compared to thermosensitive liposomes without gold coating and to the FDA-approved Doxil that was gold-coated to create a plasmon resonant coating. Release of doxorubicin from the gold-coated thermosensitive liposomes was further confirmed by tests of cell viability.

Results: Upon laser illumination at 760 nm and 88 mW/cm² power density, permeability of plasmon resonant liposomes increased by three orders of magnitude, from 70×10^-12 to 60,000x10^-12 cm/s. In control experiments, mild hyperthermia (42°C) increased permeability of these thermosensitive liposomes to just 3,700×10^-12 cm/s. Neither hyperthermia nor laser illumination elicit content release from Doxil or plasmon resonant Doxil obtained by gold coating. Laser-induced release of doxorubicin from plasmon resonant thermosensitive liposomes resulted in the loss of cell viability significantly greater than in any of the control groups.

Conclusion: Combination of thermosensitive liposomes with plasmon resonant coating enables rapid, controlled release, not currently available in pharmaceutical formulations of anticancer drugs.

Preparation of Stable Silver Nanoparticles Having Wide Red-To-Near-Infrared Extinction

The synthesis of silver nanoparticles (AgNPs) within the interlayer space of transparent layered titania nanosheet (TNS) films is investigated. A considerable number of silver ions (≈70% against the cation exchange capacity of the TNS) are intercalated in the TNS films using methyl-viologen-containing TNSs as a precursor. The silver ion (Ag+)-containing TNS films are treated with aqueous sodium tetrahydroborate (NaBH4), resulting in a gradual color change to bright blue. Various structural analyses clearly show that crystalline AgNPs are generated within the interlayer space of the TNSs. The NaBH4-treated films show intense and characteristic near-infrared (NIR) extinction spectra up to 1800 nm. The stability of the AgNPs within the TNS against oxygen and moisture is also investigated, and 96% and 82% of the AgNPs remain after standing in air for 1 month and 1 year, respectively. The NIR extinctions of the AgNP-containing TNS films are further extended by employing different preparation procedures, for example, using sintered TNS films as starting materials and irradiating the Ag+-containing TNSs with ultraviolet (UV) light. The obtained AgNP-containing TNS films exhibit photochemical activities in the production of hydrogen from ammonia borane under visible-light irradiation and the decomposition of nitrogen monoxide under UV-light irradiation.

Fucoidan-coated CuS nanoparticles for chemo-and photothermal therapy against cancer

In advanced cancer therapy, the combinational therapeutic effect of photothermal therapy (PTT) using near-infrared (NIR) light-responsive nanoparticles (NPs) and anti-cancer drug delivery-mediated chemotherapy has been widely applied. In the present study, using a facile, low-cost, and solution-based method, we developed and synthesized fucoidan, a natural polymer isolated from seaweed that has demonstrated anti-cancer effect, and coated NPs with it as an ideal candidate in chemo-photothermal therapy against cancer cells. Fucoidan-coated copper sulfide nanoparticles (F-CuS) act not only as a nanocarrier to enhance the intracellular delivery of fucoidan but also as a photothermal agent to effectively ablate different cancer cells (e.g., HeLa, A549, and K562), both in vitro and in vivo, with the induction of apoptosis under 808 nm diode laser irradiation. These results point to the potential usage of F-CuS in treating human cancer.