High Near-infrared Absorbance Research Articles

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

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

Blue emission-dominated NaYbF4@NaYF4:2%Ho@NaYF4 upconversion nanoparticles for detecting ascorbic acid.

The blue emission-dominated NaYbF4@NaYF4:2%Ho@NaYF4 (CSS) upconversion nanoparticles (UCNPs) were designed to detect ascorbic acid (AA). The blue emission of CSS was increased, ∼34 and ∼8 times higher than that of NaYF4:2%Ho@NaYbF4@NaYF4 (CSS (I)) and NaYbF4@NaYF4:20%Yb,2%Ho@ NaYF4 (CSS (II)), respectively. The dominant blue emission of CSS might be attributed to three aspects: (1) the protected NaYbF4 core for high near-infrared absorption, (2) the spatial separation of Yb3+ and Ho3+ preventing back energy transfer, and (3) their inert shell inhibiting surface quenching. It is worth noting that the fluorescence resonance energy transfer (FRET) of the CSS (donor) to MnO2 nanosheets (acceptor) was developed to trace AA. The detection limit is 0.75 μM and the detection range is 0.5-100 μM. In summary, our work not only explored the blue emission mechanism of Ho3+, but also constructed a CSS/MnO2-based nanosensing platform for the rapid and sensitive detection of AA. The blue emission of Ho3+ has promising applications in the field of sensing and detection.

UV-C driven reduction of nanographene oxide opens path for new applications in phototherapy

The main challenges associated to the application of graphene-based materials (GBM) in phototherapy are obtaining particles with lateral nanoscale dimensions and water stability that present high near-infrared (NIR) absorption. Nanosized graphene oxide (GOn) is stable in aqueous dispersion, due to the oxygen functionalities on its surface, but possesses low photothermal efficiency in NIR region. GOn total reduction originates reduced nanographene oxide (rGOn) that presents high NIR absorption, but poor water stability. In this work, we produced a partially reduced nanographene oxide (p-rGOn) by GOn photoreduction using ultraviolet radiation (UV-C), yielding nanometric particles that preserve the original water stability, but acquire high light-to-heat conversion efficiency. GOn and p-rGOn presented mean particle sizes of 170 ± 81 nm and 188 ± 99 nm, respectively. 8 h of UV-C irradiation allowed to obtain a p-rGOn stable for up 6 months in water, with a zeta potential of −32.3 ± 1.3 mV. p-rGOn water dispersions have shown to absorb NIR radiation, reaching 52.7 °C (250 µg mL−1) after 30 min NIR irradiation. Chemical characterization of p-rGOn showed a decrease in the number of characteristic oxygen functional groups, confirming GOn partial reduction. Furthermore, p-rGOn (250 µg mL−1) didn’t cause any cytotoxicity (ISO10993–5:2009(E)) towards human skin fibroblasts (HFF-1) and human skin keratinocytes (HaCat), after 24 and 48 h incubation. An innovative custom-built NIR LED-system has been developed and validated for p-rGOn photothermal effect evaluation. Finally, exposure to p-rGOn+NIR-LEDs has caused no cytotoxicity towards HFF-1 or HaCat cells, revealing its potential to be used as a safe therapy.

High temperature near IR spectral absorption of clear SiO2‐based glasses

AbstractExperimental high temperature near infrared (NIR) absorption spectra of different SiO2‐based glasses, including lead silicate crystal glass, clear soda lime silicate (SLS) glass and fused silica with low and high OH content, are compared. The more polarizable the glass, the stronger is the increase in the high temperature NIR absorption at wavelengths < 2 µm, involving a red shift of the optical bandgap edge with increasing temperature. It appears that the modified glassy Urbach's rule provides a framework for describing the temperature red shift of the absorption edge of lead silicate crystal glass, even above Tg. This red shift causes a 4–7 times lower Rosseland thermal radiation conductivity of lead crystal glass melts compared to clear SLS glass melts. Low OH fused silica is practically transparent for NIR thermal radiation, also at high temperatures above Tg. Incorporation of water in fused silica increases the NIR absorption in the spectral region 1.7–3.4 µm, for all temperatures. An upper limit of the diffusion coefficient D of water in fused silica was estimated from the time to measure the high temperature NIR spectra of thin (∼2 mm) samples: D < 4 * 10−10 m2/s at temperatures up to around 2000°C.

Multifunctional poly(3-hydroxybutyrate) composites with MoS2 for food packaging applications

Bacterial poly(3-hydroxybutyrate) (PHB) was reinforced with MoS2 nanosheets for developing multifunctional polymer composites toward active and smart packaging applications. The tensile elastic modulus was drastically increased at low concentrations of filler, even by a factor of 2.0 at only 0.5 wt% of MoS2, barely affecting the elongation at break. The nanoparticles further modified the surface characteristics of the PHB, increasing the wettability at low concentrations and reducing its roughness and topography. Regarding the barrier properties, 0.5 wt% of MoS2 reduced around 65 % of both the oxygen and water vapor permeability, although at higher concentrations these values increase even to higher values than the pure matrix. The MoS2 nanoparticles also increased the biodegradation of PHB, with the fastest degradation observed at 3.0 wt%. The high near-infrared absorption of MoS2 particles further allowed a simple and low-powered route to produce sub-millimetric perforated and breathable PHB films further controlling the UV–vis radiation absorption. Noteworthy, the composites can be used for capacitive humidity sensors through an interdigitated electrode structure with a 100 % increase in the sensitivity arising from their higher dielectric constant. Regarding the antibacterial behavior, while the presence of MoS2 did not affect the viability of gram-negative Salmonella Typhi, the composite with 3.0 wt% of MoS2 reduced the survival of gram-positive Listeria monocytogenes without any external stimulus. These results show that the addition of MoS2 nanosheets into PHB is a proper route to extend the applications of this biodegradable and compositable polymer, specially toward active and smart packaging applications.

Nontoxic silicene photothermal agents with high near-infrared absorption for disassembly of Alzheimer’s amyloid‑β fibrils

The disassembly and eliminating the amyloid-β (Aβ) aggregates has become an effective way to treat Alzheimer’s disease (AD). Herein, for the first time, the near-infrared (NIR) activated silicene nanosheets (SNSs) have been identified as an effective nontoxic photothermal conversion agent for irreversibly disassembly of the Aβ33–42 aggregates. The SNSs synthesized by a combination of mild oxidation method and liquid exfoliation method possess good biocompatibility and biodegradability, and high near-infrared photothermal conversion capabilities. Under NIR light, the SNSs could disassemble the large and dense Aβ33–42 mature fibrils into short fibrils and even form thin films, leading to the degradation rate of 96.47%. The circular dichroism spectrum, fluorescent spectra, and nanostructure were analyzed to monitor the photothermal degradation of mature Aβ33–42 fibrils for elaborating the mechanism beneath. This study might provide a clue for developing potential therapeutic strategy for AD and related neurodegenerative diseases.

Anisotropic Plasmonic Gold Nanorod-Indocyanine Green@Reduced Graphene Oxide-Doxorubicin Nanohybrids for Image-Guided Enhanced Tumor Theranostics.

The unique physicochemical and localized surface plasmon resonance assets of gold nanorods (GNRs) have offered combined cancer treatments with real-time diagnosis by integrating diverse theragnostic modalities into a single nanoplatform. In this work, a unique multifunctional nanohybrid material based on GNRs was designed for in vitro and in vivo tumor imaging along with synergistic and combinatorial therapy of tumor. The hybrid material with size less than 100 nm was achieved by embedding indocyanine green (ICG) on mesoporous silica-coated GNRs with further wrapping of reduced graphene oxide (rGO) and then attached with doxorubicin (DOX) and polyethylene glycol. The nanohybrid unveiled noteworthy stability and competently protected the embedded ICG from further aggregation, photobleaching, and nucleophilic attack by encapsulation of GNRs-ICG with rGO. Such combination of GNRs-ICG with rGO and DOX served as a real-time near-infrared (NIR) contrast imaging agent for cancer diagnosis. The hybrid material exhibits high NIR absorption property along with three destined capabilities, such as, nanozymatic activity, photothermal activity, and an excellent drug carrier for drug delivery. The integrated properties of the nanohybrid were then utilized for the triple mode of combined therapeutics of tumor cells, through synergistic catalytic therapy and chemotherapy with combinatorial photothermal therapy to achieve the maximum cancer killing efficiency. It is assumed that the assimilated multimodal imaging and therapeutic capability in single nanoparticle platform is advantageous for future practical applications in cancer diagnosis, therapy, and molecular imaging.

Synthesis of Liquid Gallium@Reduced Graphene Oxide Core-Shell Nanoparticles with Enhanced Photoacoustic and Photothermal Performance.

This report presents nanoparticles composed of a liquid gallium core with a reduced graphene oxide (RGO) shell (Ga@RGO) of tunable thickness. The particles are produced by a simple, one-pot nanoprobe sonication method. The high near-infrared absorption of RGO results in a photothermal energy conversion of light to heat of 42.4%. This efficient photothermal conversion, combined with the large intrinsic thermal expansion coefficient of liquid gallium, allows the particles to be used for photoacoustic imaging, that is, conversion of light into vibrations that are useful for imaging. The Ga@RGO results in fivefold and twofold enhancement in photoacoustic signals compared with bare gallium nanoparticles and gold nanorods (a commonly used photoacoustic contrast agent), respectively. A theoretical model further reveals the intrinsic factors that affect the photothermal and photoacoustic performance of Ga@RGO. These core-shell Ga@RGO nanoparticles not only can serve as photoacoustic imaging contrast agents but also pave a new way to rationally design liquid metal-based nanomaterials with specific multi-functionality for biomedical applications.

Ultrasmall zirconium carbide nanodots for synergistic photothermal-radiotherapy of glioma.

Glioma is characterized by highly invasive, progressive, and lethal features. In addition, conventional treatments have been poorly effective in treating glioma. To overcome this challenge, synergistic therapies combining radiotherapy (RT) with photothermal therapy (PTT) have been proposed and extensively explored as a highly feasible cancer treatment strategy. Herein, ultrasmall zirconium carbide (ZrC) nanodots were successfully synthesized with high near-infrared absorption and strong photon attenuation for synergistic PTT-RT of glioma. ZrC-PVP nanodots with an average size of approximately 4.36 nm were prepared by the liquid exfoliation method and modified with the surfactant polyvinylpyrrolidone (PVP), with a satisfactory absorption and photothermal conversion efficiency (53.4%) in the near-infrared region. Furthermore, ZrC-PVP nanodots can also act as radiosensitizers to kill residual tumor cells after mild PTT due to their excellent photon attenuating ability, thus achieving a significant synergistic therapeutic effect by combining RT and PTT. Most importantly, both in vitro and in vivo experimental results further validate the high biosafety of ZrC-PVP NDs at the injected dose. This work systematically evaluates the feasibility of ZrC-PVP NDs for glioma treatment and provides evidence of the application of zirconium-based nanomaterials in photothermal radiotherapy.

Size-controllable covalent organic frameworks with high NIR absorption for targeted delivery of glucose oxidase

Targeted delivery of glucose oxidase (GOx) by covalent organic frameworks (COFs) has long been a great challenge due to their hydrophobic surface and large size. Herein, an effective strategy to synthesize COFs with well-controlled size and good water-dispersiblity was reported. The surface of COFs was further modified with biomolecule, which not only endowed COFs with good biocompatibility and selectivity towards cancer cells, but also made the system especially responsive to near infrared (NIR) light. The strong Vander Waals force and hydrogen interactions between COFs and GOx quenched the fluorescence of GOx, allowed high loading capacity and finally resulted into an excellent synergetic photothermal and starvation therapy mode, which fundamentally kill cancer cells and inhibit migration without using any chemical drugs or photothermal regents. This work provides a new prospect for synthesis and modification of COFs with controllable property, and sheds insight into designing new photothermal and starvation therapy to achieve much better therapeutic effect with negligible side effects.

Cesium polytungstate in sputtered solar control films. II. Electronic structure and water-induced defects

The origin of low conductivity and high near-infrared absorption observed in sputtered Cs-polytungstate (CPT) thin films was studied using x-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS), and first-principles calculations. The film's resistivity was directly correlated with the intensity of XPS W5+4f peaks, and the mobility of the conduction band (CB) electrons was evaluated as 1.27 × 10−7 cm2 V−1 s−1, both implying the dominance of W5+-trapped electrons in the CB. The presence of H2O residue in the films was detected from XPS O 1s and TDS spectra, suggesting that the incorporation of water upon film deposition induced numerous W/Cs defects reported in Part I. The two representative types of optical profiles were reproduced by first-principles calculations with W-deficient CPT and H2O-incorporated pyrochlore, respectively. We conclude that water-induced W/Cs defects annihilated free electrons in the films, causing loss of conductance and plasma reflection, whereas W5+-trapped electrons generated by O and W vacancies underwent polaronic excitations that generated large near-infrared absorption.

Cesium polytungstate in sputtered solar control films. I. Microstructure and optical properties

Sputtered thin films with strong near-infrared absorption and high visible transmission and electrical resistivity (≥102 Ω cm) have been obtained using highly conductive cesium tungsten bronze targets. The origin of the low electrical conductivity and high near-infrared absorption of the films has been investigated by focusing on internal defects and reported in two parts. In Paper I, the optical and electrical properties of the films and their microstructural characterization using x-ray diffraction and high-resolution transmission electron microscopy are presented. Abundant planar W and Cs defects were found on hexagonal prismatic planes that locally expanded the defect plane and triggered the hexagonal-to-orthorhombic crystallographic transition. These cationic defects diminished conduction electrons and suppressed electrical conduction, whereas oxygen vacancies generated W5+-trapped electrons to activate polaronic excitations for strong near-infrared absorption.

Metabolizable pH/H2O2 dual-responsive conductive polymer nanoparticles for safe and precise chemo-photothermal therapy

Conductive polymers with high near-infrared absorbance, have attracted considerable attention in the design of intelligent nanomedicines for cancer therapy, especially chemo-photothermal therapy. However, the unknown long-term biosafety of conductive polymers in vivo due to non-degradability hinders their clinic application. Herein, a H2O2-triggered degradable conductive polymer, polyacrylic acid (PAA) stabilized poly(pyrrole-3-COOH) (PAA@PPyCOOH), is fabricated to form nanoparticles with doxorubicin (DOX) for safe and precise chemo-phototherapy. The PAA@PPyCOOH was found to be an ideal photothermal nano-agent with good dispersity, excellent biocompatibility and high photothermal conversion efficiency (56%). After further loading of doxorubicin (DOX), PAA@PPyCOOH@DOX demonstrates outstanding photothermal performance, as well as pH/H2O2 dual-responsive release of DOX in tumors with an acidic and overexpressed H2O2 microenvironment, resulting in superior chemo-photothermal therapeutic effects. The degradation mechanism of PAA@PPyCOOH is proposed to be the ring-opening reaction between the pyrrole-3-COOH unit and H2O2. More importantly, the nanoparticles can be specifically degraded by excess H2O2 in tumor, and the degradation products were confirmed to be excreted via urine and feces. In vivo therapeutic evaluation of chemo-photothermal therapy reveals tumor growth of 4T1 breast cancer model is drastically inhibited and no apparent side-effect is detected, thus indicating substantial potential in clinic application.

NIR-driven intracellular photocatalytic oxygen-supply on metallic molybdenum carbide@N-carbon for hypoxic tumor therapy

The intracellular O2-supply not only can relieve tumor hypoxia but also enhance the effects of photodynamic therapy (PDT). In this work, metallic Mo2C@N-carbon@PEG nanoparticles were constructed to reveal the near infrared (NIR)-photocatalytic O2 generation and promote photodynamic therapy (PDT). Here, (NH4)6Mo7O24·4H2O nanorods and urea were adopted as resources that were calcined to obtain Mo2C@N-carbon nanoparticles (20 nm). All samples displayed high NIR absorption as well as photothermal conversion efficiency of up to 52.7 % (Mo2C@N-Carbon-3@PEG). The density functional theory calculations demonstrated the metallic characteristic of Mo2C and that the consecutive interband/intraband charge-transition was responsible for the high NIR harvest and redox ability of electron-hole pairs, making the NIR-photocatalytic O2 and reactive oxygen species (ROS) generation. In comparison with the pure Mo2C, the heterostructure displayed twice the performance due to the enhanced charge-segregation between Mo2C and N-carbon. Given the high X-ray absorption coefficient and photothermal ability, the nanocomposite could be used in novel computer tomography and photothermal imaging contrast. Furthermore, the novel biodegradation and metabolism behaviors of nanocomposites were investigated, which were reflected as elimination from the body (mouse) via feces and urine within 14 days. The as-synthesized Mo2C@N-Carbon@PEG nanocomposites integrated the dual-model imaging, intracellular O2-supply, and phototherapy into one nanoplatform, revealing its potential for anti-cancer therapy.

Near-Infrared-Light-Responsive Copper Oxide Nanoparticles as Efficient Theranostic Nanoagents for Photothermal Tumor Ablation.

A theranostic nanoagent exhibits great promise to improve diagnostic accuracy and therapy efficacy. Herein, a kind of theranostic nanoagent based on poly(vinylpyrrolidone) (PVP)-protected ultrasmall Cu1.2O nanoparticles (Cu1.2O NPs) is developed by a facile liquid reduction method. Attributed to high near-infrared absorbance and good biocompatibility, Cu1.2O NPs have shown significant potential for photothermal therapy. Moreover, Cu1.2O NPs with a satisfactory T1 relaxivity coefficient (r1) can be well applied as outstanding MRI contrast agents and exhibit excellent magnetic resonance imaging (MRI) ability. In vivo treatments further demonstrate that Cu1.2O NPs could be well used as multifunctional theranostic nanoagents, which achieve precise MRI and a high photothermal antitumor effect. It is expected to further promote the research and application of copper-based nanoparticles as theranostic nanoagents for cancer therapy.

Remote Optical Modulation of Cellular Electrical Activity Using Two-Dimensional Ti3C2 MXene

The ability to probe and manipulate electrophysiology at the cellular level is crucial for understanding cellular communications and enabling new therapeutics for neurological and psychiatric disorders. Nanomaterial-facilitated photothermal stimulation is a non-invasive technique to manipulate cellular electrophysiology with high spatial precision and rapid response time without the need of genetic modifications. Although recently reported Si-, Au-, and C-based nanomaterials are promising candidates for photothermal stimulation of electrically active cells and tissues, they exhibit limited photothermal conversion efficiency in the near-infrared (NIR) window or have complicated synthesis protocols that prevents direct scale-up. Two-dimensional (2D) Ti3C2 MXene is a promising candidate for optical stimulation due to its high NIR absorption and photothermal energy conversion efficiency. Here, we report an approach for optical modulation of neuronal activity using Ti3C2 MXene flakes. Under illumination with 1 ms pulses of 10 mW NIR laser (λ = 808 nm), the local temperature rise induced by single Ti3C2 MXene flakes was measured to be 3.1 ± 0.7 K. MXene films (25 µg/cm2) and dispersed MXene flakes (100 µg/mL) were evaluated to be biocompatible with dorsal root ganglia (DRG) neurons. Both MXene films and flakes enabled photothermal stimulation of DRG neurons (and DRG networks) with incident energies in the micro-joule regime. Optical stimulation of DRG neurons using Ti3C2 MXene flakes is safe and does not generate cellular stress. Due to its straightforward and large-scale synthesis, MXene can enable neuronal modulation at various scales and dimensions, thus is a powerful tool for future remote, non-genetic biological interfaces.

BioinspiredCamellia japonicacarbon dots with high near-infrared absorbance for efficient photothermal cancer therapy

Since carbon dots (CDs) exhibit excellent biocompatibility, low cytotoxicity, near-infrared (NIR) absorbance, and superior photostability, many types of CDs are considered as powerful candidates for photothermal therapy (PTT) applications. However, the development of a desirable CD is still difficult due to insufficient photothermal conversion, thus resulting in the use of high laser power densities at a high dose of CDs for the PTT effect. Herein, bioinspired sulfur-doped CDs (S-CDs) with strong NIR absorbance were prepared from Camellia japonica flowers via a facile hydrothermal method for enhancing the photothermal conversion efficiency. The as-prepared S-CDs exhibited various advantages including cost-effective preparation, good water-solubility, high biocompatibility, intense NIR absorption, and excellent photothermal effect with robust photostability. Most importantly, the optimal low dose of S-CDs (45 μg mL-1) successfully led to efficient PTT performance with a high photothermal conversion efficiency (55.4%) under moderate laser power (808 nm, 1.1 W cm-2) for safe and effective cancer therapy.

Systematic study of the structure-property relationship of a series of near-infrared absorbing push-pull heptamethine chromophores for electro-optics

This study reports the facile synthesis, characterization and quantitative structure-property relationship analysis of molecular and material properties of tricyanofuran-based (TCF) dipolar heptamethines with different electron donors of indoline ( F1 ), benzo[ e ]- indoline ( F2 ), benz[ cd ]indoline ( F3 ), and Michler’s base derivatives ( M1 and M2 ). The linear and nonlinear optical (NLO) properties of these chromophores have been thoroughly investigated, and the relationship between molecular and bulk response has been analyzed and compared with dipolar tetraene AJLZ53 as one of the best chromophores for electro-optic (EO) devices. In particular, we provide responsible data collection and analysis of optical and EO properties for poled thin films using a widely-recognized and accredited methodology of prism coupling system with the help of rigid oriented gas model. We found that these push-pull heptamethines with synthetic efficacy exhibit high near-infrared absorption, excellent chemical stability and large hyperpolarizabilities ( β ) varied from 1,023×10−30 esu for F1 , 3,047×10−30 esu for M1 , and 3,547×10−30 esu for F3 at 1,304 nm in poled films, respectively. The β values of these molecules are among the highest ones for TCF-based dipolar chromophores, and also agree well with reported analytical results in the solutions. In poled polymers with a modest chromophoric loading density of 1.3× 1020 cm−3, M1 and M2 give a high poled-induced noncentrosymmetric order and relatively large r 33 values around 40 pm V−1 at 1,304 nm, indicative of large μβ values and suitable structural modification for high poling efficiency. Furthermore, a binary EO polymer based on the co-loading of M1 and AJLZ53 achieve a large r 33 value of 143.3 pm V−1 at 1,304 nm. Our studies suggest that concise synthesis and molecular design of push-pull polymethines can be well guided by the tabulation of their linear and NLO properties in bulk materials, and streamline future development of high performance organic EO materials for photonic applications.

On-demand drug release nanoplatform based on fluorinated aza-BODIPY for imaging-guided chemo-phototherapy

Intelligent drug delivery systems (DDS), integrating with multi-modal imaging guidance and controlled drug release, have practical significance in enhancing the therapeutic efficiency of tumors. Herein, fluorinated aza-boron-dipyrromethene (NBF) with high near-infrared absorption is synthesized by introducing nonadecafluorodecanoic acid into aza-BODIPY via the amide bond. Through the co-precipitation methods, nanoparticles (NPs) based on NBF are fabricated and the obtained NBF NPs can not only load with DOX with a high loading efficiency (25%, DNBF NPs), but also absorb PFC droplets (1H-perfluoropentane) with bp of 42 °C because of the fluorinated chains inside NBF NPs (PDNBF NPs). Under 808-nm laser irradiation, the hyperthermia effect of NBF could induce the liquid-gas phase transition of PFC droplets, triggering the burst release of DOX and enhancing echo signals for ultrasound imaging as well. With efficient enrichment of PDNBF NPs at tumor site as revealed by in vivo ultrasound imaging and photoacoustic imaging, significant improvement in inhibiting tumor growth is achieved with PDNBF NPs under laser irradiation without noticeable side effects. The work presents a multifunctional organic DDS with great biocompatibility, high drug loading efficiency and light-stimuli-responsive drug release, which provides a new strategy for the manufacture of intelligent composite theranostic nanoplatform.

Low-toxicity FePt nanoparticles for the targeted and enhanced diagnosis of breast tumors using few centimeters deep whole-body photoacoustic imaging

A considerable amount of early breast tumors grown at a depth over 2 cm in breast tissues. With high near-infrared absorption of iron-platinum (FePt) nanoparticles, we achieved few centimeters deep photoacoustic (PA) imaging for the diagnosis of breast tumors. The imaging depth can extend over 5 cm in chicken breast tissues at the low laser energy density of 20 mJ/cm2 (≤ ANSI safety limit). After anti-VEGFR conjugation and the tail-vein injection, we validated their targeting on tumor sites by the confocal microscopy and PA imaging. Using a home-made whole-body in vivo PA imaging, we found that the nanoparticles were rapidly cleared away from the site of the tumor and majorly metabolized through the liver. These results validated the clinical potential of the FePt nanoparticles in the low-toxicity PA theragnosis of early breast cancer and showed the capacity of our whole-body PA imaging technique on monitoring the dynamic biodistribution of nanoparticles in the living body.