Nanostructural Control Enables Optimized Photoacoustic–Fluorescence–Magnetic Resonance Multimodal Imaging and Photothermal Therapy of Brain Tumor

The performance of current multimodal imaging contrast agents is often constrained by the tunability of nanomaterial structural design. Herein, the influence of nanostructure on the overall imaging performance of a composite nanomaterial for multimodal imaging of brain tumors is studied. Newly designed near‐infrared molecules (TC1) are encapsulated into nanocomposites with ultrasmall iron oxide nanoparticles (UIONPs), forming stable nanoagents for multimodal imaging and photothermal therapy (PTT). Through a modified nanoprecipitation method, the synthesis of nanocomposites denoted as HALF is realized, in which UIONPs are restricted to half of the nanosphere. Such a unique nanostructure that physically separates TC1 and UIONPs is found with capabilities of mitigating fluorescence quenching, preserving the good performance of photoacoustic imaging, and enhancing the magnetic resonance imaging signals. Decorated with a peptide ligand cRGD for better brain tumor targeting, HALF‐cRGD is evaluated both in vitro and in vivo as imaging contrast agents and photothermal therapeutic agents. The good imaging performance and PTT effect of HALF‐cRGD in mice models indicate that the rational design and control of nanostructures could optimize multimodal imaging performance using the same components.     

Carbon Quantum Dots Codoped with Nitrogen and Lanthanides for Multimodal Imaging

Nanoparticles are increasingly being used as advantageous alternatives to commonly used contrast agents in bioimaging, not only due to their improved imaging capabilities but also their great potential in theranostics. Herein, carbon quantum dots (CQDs) codoped with nitrogen and lanthanides (i.e., Gd and Yb) are synthesized using a one‐pot microwave‐assisted hydrothermal method and evaluated as improved multimodal contrast agents for imaging purposes. The obtained doped‐CQDs exhibit an intense fluorescence emission with excellent quantum yields (66 ± 7%) along with outstanding magnetic resonance (MR) and computed tomography (CT) contrast properties, without showing appreciable cytotoxicity after their exposure to three different cell lines for 24 and 72 h. Such outstanding features turn these nanoparticles into ideal labels for multimodal imaging. To actually prove such potential, first, these CQDs codoped with N and lanthanides are successfully applied to in vitro fluorescence, and MR and CT cell imaging. In addition, such nanoparticles demonstrate to have great potential as contrast agents for multimodal imaging in vivo as significant MR and CT contrast enhancement is observed in the bladder and kidneys of a mouse after their intravenous injection into the tail vein.     

Ultrastable and Biocompatible NIR‐II Quantum Dots for Functional Bioimaging

Fluorescence bioimaging in the second near‐infrared spectral region (NIR‐II, 1000–1700 nm) can provide advantages of high spatial resolution and large penetration depth, due to low light scattering. However, NIR‐II fluorophores simultaneously possessing high brightness, good stability, and biocompatibility are very rare. Hydrophobic NIR‐II emissive PbS@CdS quantum dots (QDs) are surface‐functionalized, via a silica and amphiphilic polymer (Pluronic F‐127) dual‐layer coating method. The as‐synthesized PbS@CdS@SiO₂@F‐127 nanoparticles (NPs) are aqueously dispersible and possess a quantum yield of ≈5.79%, which is much larger than those of most existing NIR‐II fluorophores. Thanks to the dual‐layer protection, PbS@CdS@SiO₂@F‐127 NPs show excellent chemical stability in a wide range of pH values. The biocompatibility of PbS@CdS@SiO₂@F‐127 NPs is studied, and the results show that the toxicity of the NPs in vivo could be minimal. PbS@CdS@SiO₂@F‐127 NPs are then utilized for in vivo and real‐time NIR‐II fluorescence microscopic imaging of mouse brain. The architecture of blood vessels is visualized and the imaging depth reaches 950 µm. Furthermore, in vivo NIR‐II fluorescence imaging of gastrointestinal tract is achieved, by perfusing PbS@CdS@SiO₂@F‐127 NPs into mice at a rather low dosage. This work illustrates the potential of ultrastable, biocompatible, and bright NIR‐II QDs in biomedical and clinical applications, which require deep tissue imaging.     

Bright AIEgen–Protein Hybrid Nanocomposite for Deep and High‐Resolution In Vivo Two‐Photon Brain Imaging

Two‐photon fluorescence imaging allows in vivo study of biological structures and activities in deep tissues, in which bright fluorophores with high photostability and good biocompatibility are highly desirable. Herein, a small‐molecule fluorogen with aggregation‐induced emission (AIEgen) is complexed with fetal bovine serum (FBS) proteins to develop a protein‐sized AIEgen–protein hybrid nanocomposite (TPEPy‐FBS) with bright far‐red/near‐infrared (NIR) emission, excellent photostability, and low phototoxicity for deep and high‐resolution in vivo two‐photon brain vasculature imaging. Upon complexation with FBS, the fluorescence of TPEPy is greatly intensified and a sixfold enhancement is observed with 10% FBS in aqueous media. The yielded TPEPy‐FBS shows good physical stability in aqueous media and the phototoxicity of TPEPy is dramatically inhibited after complexation with FBS. Moreover, TPEPy‐FBS exhibits bright two‐photon fluorescence in far‐red/NIR region and good photostability upon femtosecond laser excitation, which facilitates high performance in vivo imaging. A large imaging depth of 656 µm is obtained in brain vasculature network imaging with a high signal‐to‐background ratio of 234, where a small blood capillary of 1.05 µm can be resolved at an imaging depth of 656 µm. Highlighted is a simple and versatile strategy to develop efficient two‐photon probes for in vivo biological imaging.     

NIR‐II Excitable Conjugated Polymer Dots with Bright NIR‐I Emission for Deep In Vivo Two‐Photon Brain Imaging Through Intact Skull

Methods for noninvasive brain imaging are highly desirable to study brain structures in neuroscience. Two‐photon fluorescence microscopy (2PFM) with near‐infrared (NIR) light excitation is a relatively noninvasive approach commonly used to study brain with high spatial resolution and large imaging depth. However, most of the current studies require cranial window implantation or skull‐thinning methods due to attenuation of excitation light. 2PFM through intact mouse skull is challenging due to strong scattering induced by skull bone. Herein, NIR‐II light excitable single‐chain conjugated polymer dots (CPdots) with bright fluorescence in NIR‐I region (peak at ≈725 nm and quantum yield of 20.6 ± 1.0%) are developed for deep in vivo two‐photon fluorescence (2PF) imaging of intact mouse brain. The synthesized CPdots exhibit good biocompatibility, high photostability, and large two‐photon absorption cross section. The CPdots allow 2PF images acquired upon excitation at 800, 1040 and 1200 nm with the highest signal‐to‐background ratio of 208 demonstrated for 1200 nm excitation. Moreover, a 3D reconstruction of the brain blood vessel network is obtained with a large vertical depth of 400 µm through intact skull. This work demonstrates great potential of bright NIR fluorophores for in vivo deep tissue imaging.     

Perfluorooctyl Bromide Polymeric Capsules as Dual Contrast Agents for Ultrasonography and Magnetic Resonance Imaging

Polymeric capsules with a thick shell made of biodegradable and biocompatible polymer and a liquid core of perfluorooctyl bromide (PFOB) were evaluated for stability as well as for ultrasound and magnetic resonance imaging (MRI) contrast enhancement. The method of preparation allows the mean capsule diameter to be regulated between 70 nm and 25 µm and the capsule thickness‐to‐radius ratio from 0.25 to 0.54. Capsule diameter remains stable at 37 °C in phosphate buffer for at least 4 and 6 h for nanocapsules and microcapsules, respectively. The in vitro ultrasound signal‐to‐noise ratio (SNR) was measured from 40 to 60 MHz for 6 µm and 150 nm capsules: the SNR increases with capsule concentration up to 20–25 mg mL⁻¹, and then reaches a plateau that depends on capsule diameter (13.5 ± 1.5 dB for 6 µm and 6 ± 2 dB for the 150 nm capsules). The ultrasound SNR is stable for up to 20 min for microcapsules and for several hours for nanocapsules. For nanocapsules, the thinner the shell, the larger the SNR and the more compressible the capsules. Nanocapsule suspensions imaged in vitro with a commercial ultrasound imaging system (normal and tissue harmonic imaging modes, 7–14 MHz probe) were detected down to concentrations of 12.5 mg mL⁻¹. Injections of nanocapsules (200 µg ml⁻¹) in mice in vivo reveal that the initial bolus passage presents significant ultrasound enhancement of the blood pool during hepatic imaging (7–14 MHz probe, tissue harmonic imaging mode). ¹⁹F‐MRI images were obtained in vitro at 9.4T using spin‐echo and gradient echo sequences and allow detecting nanocapsules in suspension (50 mg mL⁻¹). In conclusion, these results show initial feasibility for development of these capsules toward a dual‐modality contrast agent.     

Engineering of Multifunctional Nano‐Micelles for Combined Photothermal and Photodynamic Therapy Under the Guidance of Multimodal Imaging

The integration of diagnostic and therapeutic functionalities on a single theranostic nano‐system holds great promise to enhance the accuracy of diagnosis and improve the efficacy of therapy. Herein, a multifunctional polymeric nano‐micelle system that contains a photosensitizer chlorin e6 (Ce6) is successfully fabricated, at the same time serving as a chelating agent for Gd³⁺, together with a near‐infrared (NIR) dye, IR825. With a r₁ relativity 7 times higher than that of the commercial agent Magnevist, strong fluorescence offered by Ce6, and high NIR absorbance attributed to IR825, these theranostic micelles can be utilized as a contrast agent for triple modal magnetic resonance (MR), fluorescence, and photoacoustic imaging of tumors in a mouse model. The combined photothermal and photodynamic therapy is then carried out, achieving a synergistic anti‐tumor effect both in vitro and in vivo. Different from single photo treatment modalities which only affect the superficial region of the tumor under mild doses, the combination therapy at the same dose using this agent is able to induce significant damage to both superficial and deep parts of the tumor. Therefore, this work presents a polymer based theranostic platform with great potential in multimodal imaging and combination therapy of cancer.     

Multicore Liquid Perfluorocarbon‐Loaded Multimodal Nanoparticles for Stable Ultrasound and 19F MRI Applied to In Vivo Cell Tracking

Ultrasound is the most commonly used clinical imaging modality. However, in applications requiring cell‐labeling, the large size and short active lifetime of ultrasound contrast agents limit their longitudinal use. Here, 100 nm radius, clinically applicable, polymeric nanoparticles containing a liquid perfluorocarbon, which enhance ultrasound contrast during repeated ultrasound imaging over the course of at least 48 h, are described. The perfluorocarbon enables monitoring the nanoparticles with quantitative ¹⁹F magnetic resonance imaging, making these particles effective multimodal imaging agents. Unlike typical core–shell perfluorocarbon‐based ultrasound contrast agents, these nanoparticles have an atypical fractal internal structure. The nonvaporizing highly hydrophobic perfluorocarbon forms multiple cores within the polymeric matrix and is, surprisingly, hydrated with water, as determined from small‐angle neutron scattering and nuclear magnetic resonance spectroscopy. Finally, the nanoparticles are used to image therapeutic dendritic cells with ultrasound in vivo, as well as with ¹⁹F MRI and fluorescence imaging, demonstrating their potential for long‐term in vivo multimodal imaging.     

Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability

This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence microscopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characterizations and a state‐of‐the‐art image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a log‐lormal length distribution and that their mean length can be robustly tuned in the 5–50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics.     

All‐in‐One Phototheranostics: Single Laser Triggers NIR‐II Fluorescence/Photoacoustic Imaging Guided Photothermal/Photodynamic/Chemo Combination Therapy

Development of single near‐infrared (NIR) laser triggered phototheranostics for multimodal imaging guided combination therapy is highly desirable but is still a big challenge. Herein, a novel small‐molecule dye DPP‐BT is designed and synthesized, which shows strong absorption in the first NIR window (NIR‐I) and fluorescence emission in the second NIR region (NIR‐II). Such a dye not only acts as a dual‐modal contrast agent for NIR‐II fluorescence and photoacoustic (PA) imaging, but also serves as a combined therapeutic agent for photothermal therapy (PTT) and photodynamic therapy (PDT). The single NIR laser triggered all‐in‐one phototheranostic nanoparticles are constructed by encapsulating the dye DPP‐BT, chemotherapy drug DOX, and natural phase‐change materials with a folic acid functionalized amphiphile. Notably, under NIR laser irradiation, DOX can effectively release from such nanoparticles via NIR‐induced hyperthermia of DPP‐BT. By intravenous injection of such nanoparticles into Hela tumor‐bearing mice, the tumor size and location can be accurately observed via NIR‐II fluorescence/PA dual‐modal imaging. From in vitro and in vivo therapy results, such nanoparticles simultaneously present remarkable antitumor efficacy by PTT/PDT/chemo combination therapy, which is triggered by a single NIR laser. Overall, this work provides an innovative strategy to design and construct all‐in‐one nanoplatforms for clinical phototheranostics.     

Nitrogen‐Doped Carbon Quantum Dot Stabilized Magnetic Iron Oxide Nanoprobe for Fluorescence,Magnetic Resonance,and Computed Tomography Triple‐Modal In Vivo Bioimaging

Multimodal imaging, which combines complementary information of two or more imaging modalities, offers huge advantages. In this paper, the synthesis, characterization, and application of superparamagnetic nitrogen‐doped carbon‐iron oxide hybrid quantum dots (C‐Fe₃O₄ QDs) is reported for triple‐modal bioimaging through fluorescence/magnetic resonance/computed tomography (FL/MR/CT). Especially, C‐Fe₃O₄ QDs are synthesized by using poly (γ‐glutamic acid) as a precursor and stabilizer via a green and facile one‐pot hydrothermal approach. The as‐prepared C‐Fe₃O₄ QDs exhibit excellent water dispersibility, wavelength‐tunable FL property with high quantum yield of about 21.6%, good photostability, strong superparamagnetic property as well as favorable biocompatibility. Meanwhile, these C‐Fe₃O₄ QDs also show a transverse relaxivity value (r ₂) of 154.10 mm ^?1 s^?1 for T₂‐weighted MR imaging mode and an observable X‐ray attenuation effect for CT imaging mode. Moreover, the in vivo bioimaging of tumor‐bearing nude mice by combining FL, MR, and CT images further demonstrates that the as‐prepared C‐Fe₃O₄ QDs can be readily and efficiently used in FL/MR/CT triple‐modal tumor imaging. Hence, the new and facile one‐pot synthesis strategy for preparing multifunctional C‐Fe₃O₄ QDs nanoprobes provides a convenient way for achieving an effective and versatile agent for tumorous bioimaging/or diagnostics.     

Tracking of Transplanted Human Mesenchymal Stem Cells in Living Mice using Near‐Infrared Ag2S Quantum Dots

Stem cell therapeutics has emerged as a novel regenerative therapy for tissue repair in the last decade. However, dynamically tracking the transplanted stem cells in vivo remains a grand challenge for stem cell‐based regeneration medicine in full understanding the function and the fate of the stem cells. Herein, Ag₂S quantum dots (QDs) in the second near‐infrared window (NIR‐II, 1.0–1.4 μm) are employed for dynamically tracking of human mesenchymal stem cells (hMSCs) in vivo with high sensitivity and high spatial and temporal resolution. As few as 1000 Ag₂S QDs‐labeled hMSCs are detectable in vivo and their fluorescence intensity can maintain up to 30 days. The in situ translocation and dynamic distribution of transplanted hMSCs in the lung and liver can be monitored up to 14 days with a temporal resolution of 100 ms. The in vivo high‐resolution imaging indicates the heparin‐facilitated translocation of hMSCs from lung to liver as well as the long‐term retention of hMSCs in the liver contribute to the treatment of liver failure. The novel NIR‐II imaging offers a possibility of tracking stem cells in living animals with both high spatial and temporal resolution, and encourages the future clinical applications in imaging‐guided cell therapies.     

CoTe2量子点的制备、结构及光学性质研究（特邀）

近年来,过渡金属碲化物（TMTs）以其独特的晶体结构和优异的物化特性引起了科学界的广泛关注和研究。本文采用超声法制备CoTe₂量子点（QDs）,通过TEM、AFM、EDS、XPS、XRD、FTIR等技术手段对制备的CoTe₂ QDs进行了形貌和结构的表征,同时使用分光光度计(UV-Vis)、光致发光谱(PL)和光致发光激发光谱(PLE)研究了CoTe₂ QDs的光学性质。结果表明,制备得到的CoTe₂ QDs分散性良好、粒径均匀、呈现球形形貌,晶粒的平均直径约为3.1 nm,平均高度约为2.9 nm;CoTe₂ QDs在红外波段存在明显的吸收,吸收值随稀释浓度的增加而降低;当激发光波长和发射光波长依次增加时,PL和PLE峰出现红移,具有明显的Stokes位移效应,表明CoTe₂ QDs的光致发光具有激发波长依赖性;CoTe₂ QDs具有光致多色发光特性,不同激发光波长可发出不同颜色的光;荧光量子产率可达62.6%。CoTe₂ QDs优异的光学特性尤其是在红外波段的吸收和发光特性,表明其在红外探测、激光防护涂层、荧光成像、多色发光和纳米光子器件等研究领域中具有重要的潜在应用价值,有望成为一种新型红外探测材料。     

Gadolinium‐Doped Persistent Nanophosphors as Versatile Tool for Multimodal In Vivo Imaging

Recent breakthroughs in the rational development of multifunctional nanocarriers have highlightened the advantage of combining the complementary forces of several imaging modalities into one single nanotool fully dedicated to the biomedical field and diagnosis applications. A novel multimodal optical‐magnetic resonance imaging nanoprobe is introduced. Designed on the basis of a spinel zinc gallate structure doped with trivalent chromium and gadolinium, this nanocrystal bears the ability to serve as both a highly sensitive persistent luminescence nanoprobe for optical imaging, and a negative contrast agent for highly resolved magnetic resonance imaging (MRI). Additional proof is given that surface coverage can be modified in order to obtain stealth nanoparticles highly suitable for real‐time in vivo application in mice, showing delayed reticulo‐endothelial uptake and longer circulation time after systemic injection.     

PbS/CdS/ZnS Quantum Dots: A Multifunctional Platform for In Vivo Near‐Infrared Low‐Dose Fluorescence Imaging

Over the past decade, near‐infrared (NIR)‐emitting nanoparticles have increasingly been investigated in biomedical research for use as fluorescent imaging probes. Here, high‐quality water‐dispersible core/shell/shell PbS/CdS/ZnS quantum dots (hereafter QDs) as NIR imaging probes fabricated through a rapid, cost‐effective microwave‐assisted cation exchange procedure are reported. These QDs have proven to be water dispersible, stable, and are expected to be nontoxic, resulting from the growth of an outer ZnS shell and the simultaneous surface functionalization with mercaptopropionic acid ligands. Care is taken to design the emission wavelength of the QDs probe lying within the second biological window (1000–1350 nm), which leads to higher penetration depths because of the low extinction coefficient of biological tissues in this spectral range. Furthermore, their intense fluorescence emission enables to follow the real‐time evolution of QD biodistribution among different organs of living mice, after low‐dose intravenous administration. In this paper, QD platform has proven to be capable (ex vivo and in vitro) of high‐resolution thermal sensing in the physiological temperature range. The investigation, together with the lack of noticeable toxicity from these PbS/CdS/ZnS QDs after preliminary studies, paves the way for their use as outstanding multifunctional probes both for in vitro and in vivo applications in biomedicine.     

Molecular Engineering of NIR-II AIE Luminogen Excited at 1700 nm for Ultradeep Intravital Brain Two-Photon Fluorescence Imaging

The limited tissue penetration depth and spatial resolution are the major bottlenecks for deep-brain imaging. In this study, molecular engineering by tailoring electron donors is conducted to develop for the first time an NIR-II (second near-infrared) emissive fluorescence probe, namely DCTBT, for effective deep-brain two-photon fluorescence imaging. Benefiting from its good biocompatibility, high photostability, bright NIR-II emission as aggregates and large two-photon fluorescence action cross section at the 1700 nm excitation window, DCTBT offers the imaging depths of 2180 and 1135 µm in mouse brain with removed and intact skull, respectively. These results are the record depths for brain imaging, compared to all kinds of fluorescent probes and all modalities of multiphoton microscopy at all demonstrated excitation wavelengths. Moreover, with DCTBT labeling, hemodynamic imaging of blood flow in mouse brain vessels down to a depth of 714 µm with the intact skull is achieved. Multiphoton fluorescence imaging with the NIR-II probe DCTBT excited at the 1700 nm window may readily provide methodology for deep-brain structural and hemodynamic research.     

Biomimetic Natural Killer Membrane Camouflaged Polymeric Nanoparticle for Targeted Bioimaging

In the present study, a biomimetic nanoconstruct (BNc) with a multimodal imaging system is engineered using tumor homing natural killer cell membrane (NKM), near‐infrared (NIR) fluorescent dye, and gadolinium (Gd) conjugate‐based magnetic resonance imaging contrast agent onto the surface of a polymeric nanoparticle. The engineered BNc is 110 ± 20 nm in size and showed successful retention of NKM proteins. The magnetic properties of the BNc are found to be tunable from 2.1 ± 0.17 to 5.3 ± 0.5 mm ^?1 s^?1 under 14.1 T, by adjusting the concentration of Gd‐lipid conjugate onto the surface of the BNc. Confocal imaging and cell sorting analysis reveal a distinguishable cellular interaction of the BNc with MCF‐7 cells in comparison to that of bare polymeric nanoparticles suggesting the tumor homing properties of NKM camouflage system. The in vitro cellular interaction results are further confirmed by in vivo NIR fluorescent tumor imaging and ex vivo MR imaging, respectively. Pharmacokinetics and biodistribution analysis of the BNc show longer circulation half‐life (≈9.5 h) and higher tumor accumulation (10% of injected dose) in MCF‐7 induced tumor‐bearing immunodeficient NU/NU nude mice. Owing to the proven immunosurveillance potential of NK‐cell in the field of immunotherapy, the BNc engineered herein would hold promises in the design consideration of nanomedicine engineering.     

Photoacoustic Imaging of Embryonic Stem Cell‐Derived Cardiomyocytes in Living Hearts with Ultrasensitive Semiconducting Polymer Nanoparticles

Human embryonic stem cell‐derived cardiomyocytes (hESC‐CMs) have become promising tools to repair injured hearts. To achieve optimal outcomes, advanced molecular imaging methods are essential to accurately track these transplanted cells in the heart. In this study, it is demonstrated for the first time that a class of photoacoustic nanoparticles (PANPs) incorporating semiconducting polymers (SPs) as contrast agents can be used in the photoacoustic imaging (PAI) of transplanted hESC‐CMs in living mouse hearts. This is achieved by virtue of two benefits of PANPs. First, strong photoacoustic (PA) signals and specific spectral features of SPs allow PAI to sensitively detect and distinguish a small number of PANP‐labeled cells (2000) from background tissues. Second, the PANPs show a high efficiency for hESC‐CM labeling without adverse effects on cell structure, function, and gene expression. Assisted by ultrasound imaging, the delivery and engraftment of hESC‐CMs in living mouse hearts can be assessed by PANP‐based PAI with high spatial resolution (≈100 µm). In summary, this study explores and validates a novel application of SPs as a PA contrast agent to track labeled cells with high sensitivity and accuracy in vivo, highlighting the advantages of integrating PAI and PANPs to advance cardiac regenerative therapies.     

InGaP@ZnS‐Enriched Chitosan Nanoparticles: A Versatile Fluorescent Probe for Deep‐Tissue Imaging

InGaP QDs overcoated with several monolayers of ZnS are covalently bound to chitosan to address the challenges of developing highly biologically stable and fluorescent nanoparticle probes for deep‐tissue imaging. Transmission electron microscopy images reveal that the average diameter of these luminescent nanoparticles is approximately 29 nm, and they contain multiple InGaP@ZnS QDs that have an average diameter between 4 and 5 nm. These new InGaP@ZnS–chitosan nanoparticles emit near the near IR region at 670 nm and are able to penetrate three times deeper into tissue (e.g., even through a mouse skull) while revealing a higher uptake efficiency into PC12 cells with a robust signal. Additionally, a cell viability assay demonstrates that these new fluorescent nanoparticles have good biocompatibility and stability with PC12 cells and neural cells. As a result, these near‐IR‐emitting nanoparticles can be used for real‐time and deep‐tissue examination of diverse specimens, such as lymphatic organs, kidneys, hearts, and brains, while leaving the tissue intact.     

Spiky Fe3O4@Au Supraparticles for Multimodal In Vivo Imaging

Nanomaterials with high biocompatibility and efficient photothermal conversion have drawn tremendous attention for tumor diagnosis and treatment. In this study, spiky Fe₃O₄@Au supraparticles (SPs) are used as phototherapy and multimodal imaging agents. The SPs show excellent photothermal and photodynamic therapeutic effects, with a photothermal conversion efficiency of 31%, and allow tumor‐targeted imaging, including computed tomographic, photoacoustic, and magnetic resonance imaging. The SPs show excellent biocompatibility both in vitro and in vivo. Furthermore, because of their remarkable absorption at near‐infrared region, the SPs obliterate a tumor under 808 nm irradiation. With their capacity for highly integrated multimodal imaging and multiple therapeutic functions, SPs are a promising agent for application to clinical practice.