Near‐Infrared‐Light‐Induced Fast Drug Release Platform: Mesoporous Silica‐Coated Gold Nanoframes for Thermochemotherapy

Development of advanced theranostics for personalized medicine is of great interest. Herein, a multifunctional mesoporous silica‐based drug delivery carrier has been developed for efficient chemo/photothermal therapy. The unique Au nanoframes@mSiO₂ spheres are elaborately prepared by utilizing Ag@mSiO₂ yolk–shell spheres as the template through spatially confined galvanic replacement method. Compared with the Ag@mSiO₂ yolk–shell spheres, the resultant Au nanoframes@mSiO₂ spheres show a strong and broad near‐infrared (NIR) absorbance in the 550–1100 nm region, high surface areas, and good biocompatibility. When irradiated with a NIR laser with a power intensity of 1 W cm^?2 at 808 nm, they can become highly localized heat sources through the photothermal effect. Moreover, the photothermal effect of the Au nanoframes can significantly promote the fast release of doxorubicin. The in vitro studies show obvious synergistic effects combining photothermal therapy and chemotherapy in the Au nanoframes@mSiO₂ spheres against Hela cells. It is believed that the as‐obtained multifunctional vehicles provide a promising platform for the combination of hyperthermia and chemotherapy for cancer treatment application.     

Human‐Serum‐Albumin‐Coated Prussian Blue Nanoparticles as pH‐/Thermotriggered Drug‐Delivery Vehicles for Cancer Thermochemotherapy

Constructing novel multimodal antitumor therapeutic nanoagents has attracted tremendous recent attention. In this work, a new drug‐delivery vehicle based on human‐serum‐albumin (HSA)‐coated Prussian blue nanoparticles (PB NPs) is synthesized. It is demonstrated that doxorubicin (DOX)/HSA is successfully loaded after in situ polymerization of dopamine onto PB NPs, and the PB@PDA/DOX/HSA NPs are highly compatible and stable in various physiological solutions. The NPs possess strong near‐infrared (NIR) absorbance, and excellent capability and stability of photothermal conversion for highly efficient photothermal therapy applications. Furthermore, a bimodal on‐demand drug release sensitively triggered by pH or NIR irradiation has been realized, resulting in a significant chemotherapeutic effect due to the preferential uptake and internalization of the NPs by cancer cells. Importantly, the thermochemotherapy efficacy of the NPs has been examined by a cell viability assay, revealing a remarkably superior synergistic anticancer effect over either monotherapy. Such multifunctional drug‐delivery systems composed of approved materials may have promising biomedical applications for antitumor therapy.     

Core–Shell Bi2Se3@mSiO2‐PEG as a Multifunctional Drug‐Delivery Nanoplatform for Synergistic Thermo‐Chemotherapy with Infrared Thermal Imaging of Cancer Cells

Thermo‐chemotherapy combining photothermal therapy (PTT) with chemotherapy has become a potent approach for antitumor treatment. In this study, a multifunctional drug‐delivery nanoplatform based on polyethylene glycol (PEG)‐modified mesoporous silica‐coated bismuth selenide nanoparticles (referred to as Bi₂Se₃@mSiO₂‐PEG NPs) is developed for synergistic PTT and chemotherapy with infrared thermal (IRT) imaging of cancer cells. The product shows no/low cytotoxicity, strong near‐infrared (NIR) optical absorption, high photothermal conversion capacity, and stability. Utilizing the prominent photothermal effect, high‐contrast IRT imaging and efficient photothermal killing effect on cancer cells are achieved upon NIR laser irradiation. Moreover, the successful mesoporous silica coating of the Bi₂Se₃@mSiO₂‐PEG NPs cannot only largely improve the stability but also endow the NPs high drug loading capacity. As a proof‐of‐concept model, doxorubicin (DOX) is successfully loaded into the NPs with rather high loading capacity (≈50.0%) via the nanoprecipitation method. It is found that the DOX‐loaded NPs exhibit a bimodal on‐demand pH‐ and NIR‐responsive drug release property, and can realize effective intracellular drug delivery for chemotherapy. The synergistic thermo‐chemotherapy results in a significantly higher antitumor efficacy than either PTT or chemotherapy alone. The work reveals the great potential of such core–shell NPs as a multifunctional drug‐delivery nanosystem for thermo‐chemotherapy.     

A New Insight of the Photothermal Effect on the Highly Efficient Visible‐Light‐Driven Photocatalytic Performance of Novel‐Designed TiO2 Rambutan‐Like Microspheres Decorated by Au Nanorods

Photocatalyst‐assisted degradation of organic pollutants, which exhibits a novel strategy for solar‐energy utilization, possesses enormous potential in various applications. Extending the light‐absorption range in the spectrum of sunlight and improving light‐conversion efficiency are always primary issues to enhance the catalytic performance of these photocatalysts. Herein, a new structure of gold‐nanorod‐decorated TiO₂ rambutan‐like microspheres is designed, which exhibits superior photocatalytic ability toward Rhodamine B in the range of visible light due to the 3D distribution of the TiO₂ branches on the surface of the microspheres, which prompts the multireflection of photons. The absorption rate of photons is thereby tremendously enhanced. This is beneficial for the generation of hot electrons originating from the localized surface plasmonic resonance of Au nanorods, which can be used to both initiate the reaction and produce the photothermal effect. Hot electrons generated by a single Au nanorod in microspheres to initiate the degradation reaction can be as high as 2.5 times of those in the nanowires' counterpart. Moreover, the heating power of a single Au nanorod in microspheres reaches up to 4.4 times higher than that in nanowires, which further accelerates the degradation rate. The reaction pathway of visible‐light‐assisted RhB degradation catalyzed by Au/TiO₂ microspheres goes through an initial N‐deethylation process instead of the complete cycloreversion catalyzed by pure TiO₂ microspheres under UV irradiation. This strategy of structure design for improved photon absorption, which achieves high degradation rate and photothermal effect, is promising for the development of novel photocatalysts.     

Photothermally Responsive Inks for Inkjet‐Printing Secure Information

2D patterns of photothermally responsive near‐infrared (NIR) absorbing gold nanostars (GNS), coated with multiple charged polymer layers, are inkjet‐printed on a glass surface. The shape of the localized surface plasmon resonance (LSPR) NIR absorption bands in the printed patterns loses its peaked form due to plasmon coupling, unless GNS are enveloped in multiple coating layers, keeping the inter‐GNS distance sufficiently large. In the latter case, the photothermal temperature increase (ΔT) induced by the NIR laser irradiation follows a ΔT versus irradiation wavelength (λ_irr) profile with the same sharply peaked shape of the LSPR bands of the liquid ink. With this result, a new paradigm for inkjet‐writing secure information is introduced, as an alternative to the current methods based on direct visual inspection of printed patterns. While the printed ink patterns of GNS with different coatings are visually indistinguishable despite their different NIR absorption spectrum, their photothermal response changes dramatically with λ_irr. This allows either to write and read simple information using a single λ_irr (YES answer for ΔT > threshold) or to use multiple λ_irr to write and read complex information like thermal bar codes and anti‐counterfeit signatures.     

Highly Ligand‐Directed and Size‐Dependent Photothermal Properties of Magnetite Particles

The development of cancer photothermal therapies, many of which rely on photothermal agents, has received significant attention in recent years. In this work, various ligands‐stabilized magnetite (Fe₃O₄) particles are fabricated and utilized as a photothermal agents for in vivo tumor‐imaging‐guided photothermal therapy. Fe₃O₄ particles stabilized by macromolecular ligands as, e.g. polyethylene glycol (PEG), exhibit a superior and more stable photothermal effect compared to Fe₃O₄ particles stabilized by small molecules like citrate, due to their stronger ability of antioxidation. In addition, the photothermal effect of Fe₃O₄ particles is revealed to increase with size, which is attributed to the redshift of Vis‐NIR spectra. Fe₃O₄ particles injected intravenously into mice can be accumulated in the tumor by the application of an external magnetic field, as revealed by magnetic resonance imaging. In vivo photothermal therapy test of PEG‐stabilized Fe₃O₄ further achieves better tumor ablation effect. Overall, this study demonstrates efficient imaging‐guided photothermal therapy of cancer that is based on Fe₃O₄ particles of optimized size and with optimized ligands. It is expected that the ligand‐directed and size‐dependent photothermal effect will provide more approaches in the design of novel materials.     

Synergistic Effect of Photothermal Therapy and Chemotherapy Using Camptothecin‐Conjugated Gold Nanorods

A combinatorial treatment comprising thermal therapy and chemotherapy offers synergistic effects by inducing localized heat to targeted tumor sites and simultaneously delivering anticancer drugs to minimize systemic side effects and enhance the cytotoxic effect. In this study, a novel platform is developed for combining photothermal therapy and chemotherapy using drug‐conjugated gold nanorods (GNRs). Camptothecin (CPT), a model anticancer drug, is chemically conjugated onto GNRs through hydrolytic ester bonding. Upon near‐infrared (NIR) irradiation, localized heat from GNRs in target areas starts to destroy tissues and cells via photothermal therapy, and the elevated temperature accelerates hydrolysis of ester linkage, rapidly releasing drugs for chemotherapy. This combined NIR triggered thermal therapy and chemotherapy with CPT‐functionalized GNRs (CPT‐GNRs) presents a synergistic effect that has high efficacy in in vitro tests, thus providing a robust platform for efficient cancer treatments.     

Enhanced Photoelectric and Photothermal Responses on Silicon Platform by Plasmonic Absorber and Omni‐Schottky Junction

Recent progresses in plasmon‐induced hot electrons open up the possibility to achieve photon harvesting beyond the fundamental limit imposed by band‐to‐band transitions in semiconductors. To obtain high efficiency, both the optical absorption and electron emission/collection are crucial factors that need to be addressed in the design of hot electron devices. Here, we demonstrate a photoresponse as high as 3.3mA/W at 1500nm on a silicon platform by plasmonic absorber (PA) and omni‐Schottky junction integrated photodetector, reverse biased at 5V and illuminated with 10mW. The PA fabricated on silicon consists of a monolayer of random Au nanoparticles (NPs), a wide‐band gap semiconductor (TiO₂) and an optically thick Au electrode, resulting in broadband near‐infrared (NIR) absorption and efficient hot‐electron transfer via an all‐around Schottky emission path. Meanwhile, time and spectral‐resolved photoresponse measurements reveal that embedded NPs with superior absorption resembling plasmonic local heating sources can transfer their energy to electricity via the photothermal mechanism, which until now has not been adequately assessed or rigorously differentiated from the photoelectric process in plasmon‐mediated photon harvesting nano‐systems.     

Photothermal/Photodynamic Therapy with Immune‐Adjuvant Liposomal Complexes for Effective Gastric Cancer Therapy

A diagnosis and therapeutic strategy for gastric cancer is developed herein by combining thermosensitive liposomal (TSL)‐based photothermal/photodynamics therapy (PTT/PDT) with chemotherapy and adjuvant immunotherapy. IR820, a photothermal agent, paclitaxel (PTX), an antitumor drug, and imiquimod (R837), a Toll‐like‐receptor‐7 agonist, are coencapsulated into a TSL drug delivery system. These formed PTX‐R837‐IR820@TSL complexes exhibit excellent optical properties, good dispersibility, and stability. Under NIR light irradiation, the measurement of singlet oxygen production and thermal efficiency indicate promising potential of PTX‐R837‐IR820@TSL complexes for PTT and PDT. Confocal microscopy and small animal NIR imaging demonstrate tumor targeting ability of the liposomal complexes to gastric cancer cells. In vitro cell viability assays and in vivo animal experiments show prominent antitumor efficiency of PTX‐R837‐IR820@TSL complexes upon NIR light irradiation. This excellent therapeutic efficacy is attributed to the simultaneous chemotherapy and PTT/PDT. Furthermore, the liposomal complexes under NIR irradiation would ablate tumors to generate a pool of tumor‐associated antigens, which is able to promote strong antitumor immune responses in the presence of those R837‐containing liposomal complexes acted as adjuvant. These results indicate that the multifunctional liposomal complexes could realize a remarkable synergistic therapeutic outcome in gastric carcinoma.     

Mobility Enhancement of P3HT‐Based OTFTs upon Blending with Au Nanorods

The mobility enhancement of organic thin‐film transistors based on poly(3‐hexylthiophene) (P3HT) by incorporating gold nanorods (Au NRs) is reported. Through varying the doping concentration and surface modifier of the Au NRs in P3HT matrix, the P3HT/Au composite with 0.5 mg mL^?1 pyridine‐capped Au NRs exhibits a hole mobility of 0.059 cm² V^?1 s^?1, this value is seven times higher than that of pristine P3HT. This remarkable improvement of mobility originates from the enhanced crystallinity and optimized orientation of P3HT after doping with Au NRs. In addition, the appropriate surface modification can produce more‐efficient hole conduction of Au NRs.     

银纳米链状材料的制备及近红外吸收性质

报道了利用水/油相界面反应,采用湿化学法合成银纳米链状材料的方法,并对这种材料的近红外吸收性质和光热转换性质进行了研究。TEM分析表明,银纳米材料为链状结构,直径约为50nm,长度分布范围较宽,从几十纳米至几百纳米。这种材料具有强的近红外吸收特性,随着还原剂加入量的增加,吸收带逐渐展宽(800～1300nm),而且平坦。这种材料具有优异光热转换性质,一经808nm激光照射,温度迅速提高。该材料优异的近红外吸收和光热转换性质,使其在红外断层成像和近红外热疗等领域具有广阔的应用前景。     

Monodisperse Polypyrrole Nanoparticles Prepared via γ‐Ray Radiolysis of Water: An Efficient Near‐Infrared Photothermal Agent for Cancer Therapy

Biosafe nanoparticles with strong near‐infrared (NIR) light photothermal conversion effect can bring effective hyperthermia as one of the promising approaches in cancer therapy. In this work, a new facile and green preparation method of polypyrrole (PPy) nanoparticles based on ⁶⁰Co γ‐ray radiation on a simple air‐saturated strong acidic aqueous solution of pyrrole (pH ≤ 1) is studied. According to the MCAP‐FACSIMILE simulation on the concentrations of the radiolysis products of water at the presence of H⁺ and O₂, the main strong oxidative radiolysis products · OH and H₂O₂ rapidly induce the polymerization of pyrrole. The size of the prepared PPy nanoparticles is about several tens of nanometers and can be controlled by the pH, the concentration of the stabilizer poly(vinyl alcohol), and the absorbed dose rate (the amount of energy absorbed per unit mass of the irradiated material within per unit of time). The PPy nanoparticles show rapid and remarkable NIR (808 nm) photothermal conversion efficiency up to 40.1% in water. Furthermore, the in vitro and in vivo experiments confirm that the prepared PPy nanoparticles exhibit enough strong NIR photothermal effect in tumor cells (4T1 and HeLa) and show a promising prospect as the NIR photothermal agent for the future cancer therapy.     

金纳米星诊疗剂的光热特性及其在光热治疗和光学相干层析成像中的应用研究

为了开发一种优异的用于光热治疗和光学相干层析成像的金纳米星诊疗剂,对金纳米星的制备、光热特性以及光热治疗和光学相干层析成像中的应用进行研究.利用尖端结构增强金纳米材料的局域表面等离子体共振特性,通过种子介导法制备了多枝化的金纳米星,多尖端的结构使其具有明显的光热效果,并探究了其作为光热治疗的诊疗剂和光学相干层析成像造影...     

Multivalent Sorbitol Probes for Near-Infrared Photothermal Cancer Therapy

Photothermal therapy (PTT) is a targeted and non-invasive therapeutic strategy for effective cancer treatment. Image-guided PTT based on bifunctional near-infrared (NIR) fluorophores has received significant attention recently and the development of NIR fluorophores is advised for targeted imaging and precise cancer therapy. In this study, a multivalent sorbitol-conjugated NIR fluorophore (4Sorbitol-800) is used as a photothermal therapeutic agent for in vivo cancer imaging and therapy because of the high tumor-targetability of the sorbitol moieties and excellent photothermal properties of the NIR heptamethine cyanine core. This NIR fluorophore demonstrates an excellent photothermal effect, which increases the temperature of the tumor by 57.4 °C upon NIR laser irradiation (1.1 W cm⁻²) for 5 min. The volumes of HT-29 tumors targeted by 4Sorbitol-800 significantly decrease over 7 days after photothermal treatment. The 4Sorbitol-800 developed in this study exhibits good in vivo safety and a highly efficient antitumor capability. Therefore, 4Sorbitol-800 in combination with NIR laser irradiation has promising potential for future clinical applications with targeted photothermal cancer therapy.     

Near-Infrared-Absorbing Diketopyrrolopyrrole-Based Semiconducting Polymer Nanoparticles for Photothermal Therapy

Photothermal therapy, an excellent therapeutic approach, has received much attention in recent years. Herein, a novel diketopyrrolopyrrole polymer (DPP-BDP) is prepared, which shows intense near-infrared (NIR) optical absorption and admirable photothermal conversion efficacy. Impressively, after assembly into nanoparticles (DB-FA), the as-prepared conjugated polymer demonstrates a uniformly distributed size around 200 nm with remarkable NIR absorption at 808 nm. Additionally, it displays high biocompatibility and photostability. More interestingly, the obtained DB-FA NPs are uptaken by cancer cells and present excellent anticancer in vitro and in vivo under 0.8 W cm⁻² or 1 W cm⁻² NIR laser irradiation, respectively. Hence, this work is expected to pave the way for using conjugated-polymer nanoparticles as a powerful photothermal agents for anticancer applications.     

Rapid synthesis and characterization of ultra‐thin shell Au@SiO2 nanorods with tunable SPR for shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS)

The recently reported shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) is considered as the next generation of advanced spectroscopy for its surface and molecular generality. With the aim to utilize the virtues of shell‐isolated strategy and advance the SHINERS technique, we introduce a silane‐based rapid synthesis method of silica‐coating Au nanorods (Au@SiO₂ NRs) with manoeuvrable ultra‐thin shell and tunable SPR. The results demonstrate that the SPR of Au NRs could be optimized to obtain large Raman enhancement using either 633 nm or 785 nm laser. Differing from previously reported Au@SiO₂ NRs synthesis method, we can tune the silica shell thickness within several nanometers to maximize the Raman signal while effectively eliminating the exterior interference. And this advanced synthesis method has also significantly reduced the silica‐coating time from one day to ca. 1 h. This method as a new development of SHINERS technique has successfully got enhanced signal in solution Raman tests of malachite green, giving a great potential to be extended to in‐situ measurement for daily life detection. Copyright © 2013 John Wiley & Sons, Ltd.     

Au/TiO2 nanorod‐based Schottky‐type UV photodetectors

TiO₂ nanorods (NRs) were synthesized on fluorine‐doped tin oxide (FTO) pre‐coated glass substrates using hydrothermal growth technique. Scanning electron microscopy studies have revealed the formation of vertically‐aligned TiO₂ NRs with length of ～2 µm and diameter of 110–128 nm, homogenously distributed over the substrate surface. 130 nm thick Au contacts using thermal evaporation were deposited on the n‐type TiO₂ NRs at room temperature for the fabrication of NR‐based Schottky‐type UV photodetectors. The fabricated Schottky devices functioned as highly sensitive UV photodetectors with a peak responsivity of 134.8 A/W (λ = 350 nm) measured under 3 V reverse bias. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Temperature–Light Dual‐Responsive Au@PNIPAm Core‐Shell Microgel‐Based Optical Devices

Au nanoparticle (AuNP) core particles coated with a poly(N‐isopropylacrylamide) (pNIPAm) shell (Au@pNIPAm) are synthesized by seed mediated free radical polymerization. Subsequently, a temperature–light‐responsive photonic device is fabricated by sandwiching the Au@pNIPAm particles between two thin layers of Au. The optical device exhibits visual color and characteristic multipeak reflectance spectra, where peak position is primarily determined by the distance between two Au layers. Dual responsivities of the photonic device are achieved by combining the photothermal effect of AuNPs core (localized surface plasmon resonance (LSPR) effect) and the temperature responsivity of the pNIPAm shell. That is, the pNIPAm shell collapses as the temperature is increased above pNIPAm's lower critical solution temperature, either by direct heat input or heat generated by AuNPs' LSPR effect. To investigate the effect of AuNPs distribution in the microgels on the devices' photothermal responsivity, the Au@pNIPAm microgel‐based etalon devices are compared with that fabricated by AuNP‐doped pNIPAm‐based microgels; in terms of response kinetics and optical spectrum homogeneity. The uniform Au@pNIPAm microgel‐based devices show a fast response and exhibit a comparatively homogeneous spectrum over the whole slide. These materials can potentially find use in drug delivery systems, active optics, and soft robotics.     

Fabrication of NIR‐Excitable SERS‐Active Composite Particles Composed of Densely Packed Au Nanoparticles on Polymer Microparticles

A simple fabrication method is demonstrated for surface‐enhanced Raman scattering (SERS)‐active plasmonic nanoballs, which consisted of Au nanoparticles (NPs) and core–shell polystyrene and amino‐terminated poly(butadiene) particles, by heterocoagulation and Au NP diffusion. The amount of Au NPs introduced into the core–shell particles increases with the concentration of Au NPs added to the aqueous dispersion of the core–shell particles. When the amount of Au NPs increases, closely packed, three‐dimensionally arranged and close‐packed Au NPs arrays are formed in the shells. Strong SERS signals from para‐mercaptophenol adsorbed onto composite particles with multilayered Au NPs arrays are obtained by near‐infrared (NIR) light illumination.     

Drop‐cast and dye‐sensitized ZnO nanorod‐based visible‐light photodetectors

We report the facile fabrication of metal–semiconductor–metal (MSM) photodetectors with dye‐sensitized ZnO nanorods (NRs) operating at wavelengths of ～405–638 nm by a simple drop casting method. The ZnO NRs were synthesized by the hydrothermal synthesis method at 75 °C. The droplet of ethanol solution containing ZnO NRs was dropped between two metal electrodes and dried at 65 °C, which allows the ZnO NRs to be adhered and contacted to both metal electrodes. When a violet light of 405 nm was illuminated into the MSM ZnO NRs‐based photodetector, the photocurrent gain was obtained as ～3.9 × 10³ at the applied bias voltage of 5 V. By increasing the bias voltage from 10 V to 15 V, the device exhibited good recovery performance with a largely reduced reset time from 85.68 s to 2.47 s and an increased on–off ratio from 17.9 to 77.4. To extend the photodetection range towards the long visible spectral region, the ZnO NRs were sensitized by the N719 dye and then drop‐cast. The dye‐sensitized ZnO NRs‐based photodetector also exhibited good photocurrent switching under 638 nm of light illumination. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)