Quaternary Zn-Ag-In-Se quantum dots for biomedical optical imaging of RGD-modified micelles

AgInZnS quantum dots as anodic emitters with strong and stable electrochemiluminescence for biosensing application

Quantum dots (QDs) have become promising electrochemiluminescence (ECL) emitters with high quantum yield and size-tunable luminescence. However, most QDs generate strong ECL emission at the cathode, developing anodic ECL-emitting QDs with excellent performance is challenging. In this work, low-toxic quaternary AgInZnS QDs synthesized by a one-step aqueous phase method were used as novel anodic ECL emitters. AgInZnS QDs exhibited strong and stable ECL emission and a low excitation potential, which could avoid the side reaction of oxygen evolution. Furthermore, AgInZnS QDs displayed high ECL efficiency (Φ_ECL) of 5.84, taking the Φ_ECL of Ru(bpy)₃²⁺/tripropylamine (TPrA) ECL system as 1. Compared to AgInS₂ QDs without Zn doping and traditional anode luminescent CdTe QDs, the ECL intensity of AgInZnS QDs was 1.62 times and 3.64 times higher than that of AgInS₂ QDs and CdTe QDs, respectively. As a proof-of-concept, we further designed an "on-off-on" ECL biosensor for detecting microRNA-141 based on a dual isothermal enzyme-free strand displacement reaction (SDR), which not only to achieve the cyclic amplification of the target and ECL signal, but also to construct a switch of the biosensor. The ECL biosensor had a wide linear range from 100 aM to 10 nM with a low detection limit of 33.3 aM. Together, the constructed ECL sensing platform is a promising tool for rapid and accurate diagnosis of clinical diseases.

Design and fabrication of CuInS2/ZnS-based QLED for automotive lighting systems

This work reports the design, manufacturing and numerical simulation approach of a 6-pixel (4.5 mm2/pixel) electroluminescent quantum dot light emitting device (QLED) based on CuInS2/ZnS quantum dots as an active layer. The QLED device was fabricated using a conventional multi-layer thin film deposition. In addition, the electrical I-V curves were measured for each pixel independently, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device, enabled us to create a computational model for the QLED based on the Transfer Hamiltonian approach to calculate the current density J (mA cm-2), the band diagram of the system, and the accumulated charge distribution. Besides, it is worth highlighting that the simulator allows the possibility to study the influence of different parameters of the QLED structure like the junction capacitance between the distinct multilayer set. Specifically, we found that the Anode-HIL interface capacitance has a greater influence in the I-V curve. This junction capacitance plays an important role in the current density increase and the QLED turn-on value when a forward voltage is applied to the device. The simulation enabled that influence could be controlled by the selection of the optimal thickness and transport layers during the experimental fabrication process. This work is remarkable since it achieves to fit simulation and experiment results in an accurate way for electroluminescent QLED devices; particularly the simulation of the device current, which is critical when designing the automotive electronics to control these new nanotechnology lighting devices in the future.

Tailoring Viruslike Mesoporous FeSe2 Hedgehogs for Controlled Drug Delivery and Synergistic Tumor Suppression

To enhance affinity to their hosts, many organisms have evolved to be spiky. This strategy has been inspiring in many fields, but in drug delivery, the feasibility has not yet been extensively explored due to the lack of suitable nanocarriers. Herein, viruslike mesoporous FeSe₂ hedgehogs with exceptional photothermal and catalytic performances have been tailored and explored for synergistic tumor therapy. The viruslike topology makes these hedgehogs highly prone to be internalized by cells. By uploading doxorubicin (Dox) into the hollow spikes and encapsulating the hedgehogs with photothermal-meltable gelatin, controlled surface morphology transition from quasi-spherical to spiky and accompanied Dox release have been achieved, with the assistance of the strong photothermal effect of FeSe₂ hedgehogs. These integrated features allow specific and controlled drug delivery, leading to synergistic tumor suppression and immunogenic tumor cell death. These results provide new insights into the tailoring of drug carriers relying on their intrinsic physical features.

Update on the development of molecular imaging and nanomedicine in China: Optical imaging

Molecular imaging has received increased attention worldwide, including in China, because it offers noninvasive characterization of widely diverse clinically significant pathologies. To achieve these goals, nanomedicine has evolved into a broad interdisciplinary field with flexible designs to accommodate and concentrate imaging and therapeutic payloads into pathological cells through selective binding to disease specific cell membrane biomarkers. This concept of personalized medicine reflects the vision of "magic bullets" proposed by German biochemist Paul Ehrlich over 100 years ago. As happening worldwide, Chinese scientists are contributing to this tsunami of science and technologies through impactful national programs and international research collaborations. This review provides a comprehensive update of Chinese innovations to address intractable unmet medical need in China and worldwide in the optical sciences. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

One-Pot Synthesis of High-Quality AgGaS2/ZnS-based Photoluminescent Nanocrystals with Widely Tunable Band Gap

Herein, we present a facile colloidal method to synthesize the high-quality AgGaS₂ nanocrystals (NCs) within 2 min via exploiting the high-reactivity S precursor and then extend this synthetic strategy to the preparation of AgGaS₂/ZnS core-shell NCs by a one-pot method without prior purification of AgGaS₂ core. The as-synthesized samples were structurally characterized to confrim the formation of AgGaS₂/ZnS core-shell NCs. The energy band gap of the AgGaS₂/ZnS NCs can be effectively tunable from 2.98 to 2.83 eV by the control of their nonstoichiometry and further continuously decreases to 1.90 eV by the preparation of alloyed AgGa_xIn_1-xS₂/ZnS NCs (1 ≤ x ≤ 0). Benefitting from the efficient band gap modulations, the photoluminescence (PL) colors of the AgGaS₂-based NCs can cover almost the whole visible region from blue (460 nm) to red (671 nm). Our work demonstrates the one-pot synthesis of AgGaS₂/ZnS core-shell NCs and their band gap engineering, which is of crucial in scalability toward industrial application and in tailoring optical characteristics of I-III-VI₂ materials.

Ultra-small aqueous glutathione-capped Ag–In–Se quantum dots: luminescence and vibrational properties

A direct aqueous synthesis, composition- and size-dependent absorption, photoluminescence, and vibrational properties of ultra-small glutathione-capped Ag-deficient Ag–In–Se quantum dots are reported.

cRGD functionalized 2,1,3-benzothiadiazole (BTD)-containing two-photon absorbing red-emitter-conjugated amphiphilic poly(ethylene glycol)-block-poly(ε-caprolactone) for targeted bioimaging

A two-photon absorbing (2PA) red emitter group was chemically conjugated onto amphiphilic poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) copolymers, and further grafted with cyclo(Arg-Gly-Asp) (cRGD) peptide to form micelle 1. Micelle 1 with cRGD targeting groups were used for targeted bioimaging. For comparison, micelle 2 without the cRGD targeting groups were also prepared and investigated. The micelles were characterized using dynamic light scattering (DLS), showing average diameters of around 77 nm. The cRGD targeting group is known to bind specifically with α_vβ₃ integrin in cancer cells. In this study, α_vβ₃ integrin overexpressed human glioblastoma U87MG cell line and α_vβ₃ integrin deficient human cervical cancer HeLa cell line were chosen. Results showed that the cRGD targeting group enhanced the cellular uptake efficiency of the micelles significantly in α_vβ₃ integrin rich U87MG cells. Higher temperature (37 °C versus 4 °C) and calcium ions (with 3 M calcium chloride in the cell culture medium versus no addition of calcium ions) enhanced the cellular uptake efficiency, suggesting that the uptake of the micelles is through the endocytosis pathway in cells. A 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assay was used to evaluate the cytotoxicity of the micelles and no significant cytotoxicity was observed. The BTD-containing two-photon absorbing emitter in the micelles showed a two-photon absorbing cross-section of 236 GM (1 GM = 1 × 10⁻⁵⁰ cm⁴ s per photonper molecule) at 820 nm, which is among the highest values reported for red 2PA emitters. Because of the two-photon absorbing characteristics, micelle 1 was successfully used for two-photon fluorescence imaging targeted to U87MG cells under a two-photon fluorescence microscope. This study is the first report regarding the targeted imaging of a specific cancer cell line (herein, U87MG) using the BTD-conjugated-fluorophore-containing block copolymers.

A two-photon absorbing (2PA) red emitter group was chemically conjugated onto amphiphilic poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) copolymers, and further grafted with cyclo(Arg-Gly-Asp) (cRGD) peptide to form micelle 1.

Progress in the Development of Chitosan-Based Biomaterials for Tissue Engineering and Regenerative Medicine

Over the last few decades, chitosan has become a good candidate for tissue engineering applications. Derived from chitin, chitosan is a unique natural polysaccharide with outstanding properties in line with excellent biodegradability, biocompatibility, and antimicrobial activity. Due to the presence of free amine groups in its backbone chain, chitosan could be further chemically modified to possess additional functional properties useful for the development of different biomaterials in regenerative medicine. In the current review, we will highlight the progress made in the development of chitosan-containing bioscaffolds, such as gels, sponges, films, and fibers, and their possible applications in tissue repair and regeneration, as well as the use of chitosan as a component for drug delivery applications.

Optical Properties, Synthesis, and Potential Applications of Cu-Based Ternary or Quaternary Anisotropic Quantum Dots, Polytypic Nanocrystals, and Core/Shell Heterostructures

This review summaries the optical properties, recent progress in synthesis, and a range of applications of luminescent Cu-based ternary or quaternary quantum dots (QDs). We first present the unique optical properties of the Cu-based multicomponent QDs, regarding their emission mechanism, high photoluminescent quantum yields (PLQYs), size-dependent bandgap, composition-dependent bandgap, broad emission range, large Stokes’ shift, and long photoluminescent (PL) lifetimes. Huge progress has taken place in this area over the past years, via detailed experimenting and modelling, giving a much more complete understanding of these nanomaterials and enabling the means to control and therefore take full advantage of their important properties. We then fully explore the techniques to prepare the various types of Cu-based ternary or quaternary QDs (including anisotropic nanocrystals (NCs), polytypic NCs, and spherical, nanorod and tetrapod core/shell heterostructures) are introduced in subsequent sections. To date, various strategies have been employed to understand and control the QDs distinct and new morphologies, with the recent development of Cu-based nanorod and tetrapod structure synthesis highlighted. Next, we summarize a series of applications of these luminescent Cu-based anisotropic and core/shell heterostructures, covering luminescent solar concentrators (LSCs), bioimaging and light emitting diodes (LEDs). Finally, we provide perspectives on the overall current status, challenges, and future directions in this field. The confluence of advances in the synthesis, properties, and applications of these Cu-based QDs presents an important opportunity to a wide-range of fields and this piece gives the reader the knowledge to grasp these exciting developments.

Wavelength-Tunable Band-Edge Photoluminescence of Nonstoichiometric Ag-In-S Nanoparticles via Ga3+ Doping

The nonstoichiometry of I-III-VI semiconductor nanoparticles, especially the ratio of group I to group III elements, has been utilized to control their physicochemical properties. We report the solution-phase synthesis of nonstoichiometric Ag-In-S and Ag-In-Ga-S nanoparticles and results of the investigation of their photoluminescence (PL) properties in relation to their chemical compositions. While stoichiometric AgInS₂ nanoparticles simply exhibited only a broad PL band originating from defect sites in the particles, a narrow band edge PL peak newly appeared with a decrease in the Ag fraction in the nonstoichiometric Ag-In-S nanoparticles. The relative PL intensity of this band edge emission with respect to the defect-site emission was optimal at a Ag/(Ag + In) value of ca. 0.4. The peak wavelength of the band edge emission was tunable from 610 to 500 nm by increased doping with Ga³⁺ into Ag-In-S nanoparticles due to an increase of the energy gap. Furthermore, surface coating of Ga³⁺-doped Ag-In-S nanoparticles, that is, Ag-In-Ga-S nanoparticles, with a GaS _x shell drastically and selectively suppressed the broad defect-site PL peak and, at the same time, led to an increase in the PL quantum yield (QY) of the band edge emission peak. The optimal PL QY was 28% for Ag-In-Ga-S@GaS _x core-shell particles, with green band-edge emission at 530 nm and a full width at half-maximum of 181 meV (41 nm). The observed wavelength tunability of the band-edge PL peak will facilitate possible use of these toxic-element-free I-III-VI-based nanoparticles in a wide area of applications.

Quantum Dots-Based Multifunctional Nano-Prodrug Fabricated by Ingenious Self-Assembly Strategies for Tumor Theranostic

The rapid developments of quantum dots (QDs)-based nanoagents for imaging tumor and tracking drug delivery have been proven to be reliable nanodiagnostic techniques. Although abundant types of QD nanoagents have been developed for fighting against cancer, it still is a challenge to control their quality and achieve prefect repetition due to the complicated synthetic steps. The precise intermolecular self-assembly (SA) may afford a facile and low-cost strategy for this challenge. Herein, a pH and H₂O₂ dual-sensitive Sb-cyclodextrin (CD)-doxorubicin (DOX) molecule was designed to construct a QD-based theranostic prodrug (named as Sb-CD-DOX-ZAISe/ZnS) via host-guest strategy (1st SA strategy), in which QDs water-transfer and drug-uploading were integrated well. That is, the nano-prodrug (NPD) inherited highly luminescent properties from "host" QDs for bioimaging, as well as environment sensitivities from "guest" Sb-CD-DOX for drug release. Experimental results indicate that the Sb-CD-DOX-ZAISe/ZnS exhibited effectively passive tumor-targeting and could provide clear imaging for malignant tumors in metaphase or advanced stages; meanwhile, after coating with folic acid (FA) through electric attraction (2nd SA strategy), the final Sb-CD-DOX-ZAISe/ZnS@FA NPD showed expected pH-controlled negative-to-positive charge reversal ability and a better curative effect compared with free DOX. Hence, fabricating nanocomposites by highly efficient self-assembly strategies is favorable toward inorganic nanoparticles-based prodrug delivery system for tumor-targeting theranostic.

TEMPO-oxidized starch nanoassemblies of negligible toxicity compared with polyacrylic acids for high performance anti-cancer therapy

There is an urgent need for developing nanocarrier of excellent biocompatibility which can selectively release drugs at desired locations that can increase intratumoral drug concentration and reduce side effects. Herein, we developed a highly biocompatible nanocarrier made of oxidized starch in delivering doxorubicin (DOX) for enhanced anti-cancer therapy. The 30% oxidized starch can spontaneously self-assemble into 30-50 nm spherical nanoassemblies under physiological concentrations. DO30 nanoassemblies possessed negligible toxicity in several cell lines and ICR mice, in contrast to severe toxicity of synthetic polyacrylic acid (PAA), both of which are carboxyl-abundant polymers. The biocompatible DO30 was further decorated with cyclic RGD (Arg-Gly-Asp-Phe-Cys) peptides via PEG linker to target αvβ3 integrin overexpressed on HepG2 cells. RGD-PEG-DO30/DOX demonstrated an enhanced tumor-targeting ability and anti-cancer property in vitro and in vivo. In general, RGD-oxidized starch nanoassemblies showed a great potential as a new type of safe and effective nanocarrier for anti-cancer therapy.

Peptide-based nanoprobes for molecular imaging and disease diagnostics

Pathological changes in a diseased site are often accompanied by abnormal activities of various biomolecules in and around the involved cells. Identifying the location and expression levels of these biomolecules could enable early-stage diagnosis of the related disease, the design of an appropriate treatment strategy, and the accurate assessment of the treatment outcomes. Over the past two decades, a great diversity of peptide-based nanoprobes (PBNs) have been developed, aiming to improve the in vitro and in vivo performances of water-soluble molecular probes through engineering of their primary chemical structures as well as the physicochemical properties of their resultant assemblies. In this review, we introduce strategies and approaches adopted for the identification of functional peptides in the context of molecular imaging and disease diagnostics, and then focus our discussion on the design and construction of PBNs capable of navigating through physiological barriers for targeted delivery and improved specificity and sensitivity in recognizing target biomolecules. We highlight the biological and structural roles that low-molecular-weight peptides play in PBN design and provide our perspectives on the future development of PBNs for clinical translation.

Water-Solubilizing Hydrophobic ZnAgInSe/ZnS QDs with Tumor-Targeted cRGD-Sulfobetaine-PIMA-Histamine Ligands via a Self-Assembly Strategy for Bioimaging

Exploring the organic-to-aqueous phase transfer of quantum dots (QDs) is significant for achieving their versatile applications in biomedical fields. In this thematic issue, surface modification, size control, and biocompatibility of QDs and QDs-based nanocomposites are core problems. Herein, the new highly fluorescent tumor-targeted QDs-clusters consisting of ZnAgInSe/ZnS (ZAISe/ZnS) QDs and sulfobetaine-PIMA-histamine (SPH) polymer with the α_νβ₃ integrin receptor cyclic RGD (c-RGD) were developed via ligand exchange and an accompanying self-assembly process. It was found that the structure of RGD-SPH QDs-clusters was propitious to reduce the capture of reticulo-endothelial system (RES) in virtue of external stealth ligands, and benefit to selectively accumulate at the tumor site after intravenous injection via active tumor targeting cooperated with the enhanced permeability and retention (EPR) effect. In the meantime, those clusters also recognized and enriched the cell surface when cocultured with the α_νβ₃ integrin receptor overexpressed malignant cells (U87MG tumor). On the basis of the results, fabricating mutil-functional nanocomposites integrated with the long-term circulation and dual-targeting effects should be an interesting strategy for imaging cancer in vitro and in vivo.

Cadmium-containing quantum dots: properties, applications, and toxicity

The marriage of biology with nanomaterials has significantly accelerated advancement of biological techniques, profoundly facilitating practical applications in biomedical fields. With unique optical properties (e.g., tunable broad excitation, narrow emission spectra, robust photostability, and high quantum yield), fluorescent quantum dots (QDs) have been reasonably functionalized with controllable interfaces and extensively used as a new class of optical probe in biological researches. In this review, we summarize the recent progress in synthesis and properties of QDs. Moreover, we provide an overview of the outstanding potential of QDs for biomedical research and innovative methods of drug delivery. Specifically, the applications of QDs as novel fluorescent nanomaterials for biomedical sensing and imaging have been detailedly highlighted and discussed. In addition, recent concerns on potential toxicity of QDs are also introduced, ranging from cell researches to animal models.

Synthetic strategies and biomedical applications of I–III–VI ternary quantum dots

In this review, we discuss recent advances of I–III–VI QDs with a major focus on synthesis and biomedical applications; advantages include low toxicity and fluorescent tuning in the biological window.

Design, fabrication, and biomedical applications of bioinspired peptide–inorganic nanomaterial hybrids

We presented the design, composition, and typical biomedical applications of bioinspired peptide–inorganic nanomaterial hybrids.

Organic-to-aqueous phase transfer of Zn–Cu–In–Se/ZnS quantum dots with multifunctional multidentate polymer ligands for biomedical optical imaging

ZnCuInSe/ZnS QDs with widely tunable PL emissions were synthesized and water-solubilized with cRGD modified multifunctional multidentate polymer (cRGD-PME) for bioimaging.

Facile fabrication of poly(acrylic acid) coated chitosan nanoparticles with improved stability in biological environments

Chitosan is one of the most important and commonly used natural polysaccharides in drug delivery for its biocompatible and biodegradable properties. However, poor blood circulation of the chitosan nanoparticles due to their cationic nature is one of the major bottlenecks of chitosan-based drug delivery systems. To address this problem, a versatile platform based on poly(acrylic acid) (PAA) coated ionically cross-linked chitosan/tripolyphosphate nanoparticles (CTS/TPP-PAA NPs), is reported. The zeta potentials of CTS/TPP and CTS/TPP-PAA NPs are approximately 33mV and -25mV, respectively. CTS/TPP NPs quickly aggregate in PBS (phosphate buffered saline) and DMEM (Dulbecco's modified Eagle's medium). Conversely, CTS/TPP-PAA NPs exhibit excellent colloidal stability in plasma solution for more than 24h. The PAA coating also endows CTS/TPP-PAA NPs with decreased protein adsorption capacity and improved buffering capacity. More importantly, the residual carboxyl and amino groups on CTS/TPP-PAA NPs provide abundant reactive sites for further functional modifications. Therefore, the CTS/TPP-PAA NPs reported here may be useful as an alternative drug delivery system.

Facile Synthesis of Cadmium-Free Zn-In-S:Ag/ZnS Nanocrystals for Bio-Imaging

High quality cadmium-free Zn-In-S:Ag doped-nanocrystals (d-NCs) were synthesized via a simple one-step noninjection route using silver nitrate, indium acetate, zinc acetate, oleylamine, S powder and 1-dodecanethiol as starting materials in an organic phase. The size and optical properties can be effectively tailored by controlling the reaction time, reaction temperature, Ag(+) dopant concentration, and the molar ratio of In to Zn. The photoluminescence wavelength of as-prepared Zn-In-S:Ag NCs covered a broad visible range from 458 nm to 603 nm. After being passivated by protective ZnS shell, the photoluminescence quantum yield (PLQY) of Zn-In-S:Ag(+) /ZnS was greatly improved to 43.5%. More importantly, the initial high PLQY of the obtained core/shell d-NCs in organic media can be preserved when being transferred into the aqueous media via ligand exchange. Finally, high quality Zn-In-S:Ag(+) /ZnS d-NCs in aqueous phase were applied as bio-imaging agents for identifying living KB cells.

Quaternary alloy quantum dots with widely tunable emission – a versatile system to fabricate dual-emission nanocomposites for bio-imaging

Highly luminescent Zn-I-III-VI-based QDs with widely composition-tuned PL emissions have been synthesized for multiscale biomedical optical imaging.

Phosphine-free synthesis of Ag-In-Se alloy nanocrystals with visible emissions

As promising heavy metal-free emitting materials, Ag-In-Se nanocrystals (NCs) are conventionally synthesized using organic phosphine agents and exhibit near-infrared emissions. In this work, we demonstrate a rapid phosphine-free approach for synthesizing Ag-In-Se alloy NCs with the emissions tunable to the visible region on the basis of the phosphine-free dissolution of Se powder. At room temperature, Se powder is reduced by dodecanethiol and dissolved in oleylamine to produce a Se precursor. The resultant Se precursor is highly active, which permits rapid synthesis at a relatively low temperature, such as at 90 °C for 150 s. By optimizing the size, structure, and composition, the photoluminescence quantum yield of the as-synthesized Ag-In-Se NCs is enhanced to up to 10%. The growth of the Ag-In-Se NCs involves composition and phase transition, which strongly depend on the reaction temperature. The Ag2Se nuclei form first, and the Ag-In-Se NCs are produced by doping In(3+) into the preformed Ag2Se nuclei. Tetragonal phase Ag-In-Se is obtained below 170 °C, while the orthorhombic phase appears over 190 °C. The potential of Ag-In-Se NCs as red emitting phosphors for lighting-emitting diodes is further demonstrated.

Pod-Like Supramicelles with Multicompartment Hydrophobic Cores Prepared by Self-Assembly of Modified Chitosan

In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by self-assembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam) (PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam) (PNVCL-COOH) chains onto N-phthaloylchitosan (PHCS) backbone. ¹H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and pH presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.

Water-soluble Zn–Ag–In–Se quantum dots with bright and widely tunable emission for biomedical optical imaging

In this work, we synthesized water-soluble quaternary cadmium-free Zn–Ag–In–Se quantum dots with bright and widely tunable emission, and explored their potential in tumor-specific imaging in vitro and in vivo.

Theranostic unimolecular micelles based on brush-shaped amphiphilic block copolymers for tumor-targeted drug delivery and positron emission tomography imaging

Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for (64)Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(L-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile and a uniform size distribution. A significantly higher cellular uptake of TRC105-conjugated micelles was observed in CD105-positive human umbilical vein endothelial cells (HUVEC) than nontargeted micelles due to CD105-mediated endocytosis. In contrast, similar and extremely low cellular uptake of both targeted and nontargeted micelles was observed in MCF-7 human breast cancer cells (CD105-negative). The difference between the in vivo tumor accumulation of (64)Cu-labeled TRC105-conjugated micelles and that of nontargeted micelles was studied in 4T1 murine breast tumor-bearing mice, by serial positron emission tomography (PET) imaging and validated by biodistribution studies. These multifunctional unimolecular micelles offer pH-responsive drug release, noninvasive PET imaging capability, together with both passive and active tumor-targeting abilities, thus making them a desirable nanoplatform for cancer theranostics.

A simple solution-phase approach to synthesize high quality ternary AgInSe2 and band gap tunable quaternary AgIn(S1-xSex)2 nanocrystals

A facile solution-phase route for the preparation of AgInSe2 nanocrystals was developed by using silver nitrate, indium stearate, and oleylamine-selenium (OAm-Se) as precursors. The evolution process of the AgInSe2 nanocrystals is discussed in detail and different reaction conditions all have a great impact on the growth and morphology of the nanocrystals. Alloyed AgIn(S1-xSex)2 nanocrystals with controlled composition across the entire range (0 ≤ x ≤ 1) was also successfully prepared by modulating the S/Se reactant mole ratio. X-ray diffraction (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were used to confirm that the alloyed AgIn(S1-xSex)2 nanocrystals are homogeneous. The UV-vis absorption spectra revealed that the band gap energies of the alloyed AgIn(S1-xSex)2 nanocrystals could be continuously tuned by increasing the Se content.