Solid‐Phase Synthesis of Molecularly Imprinted Polymer Nanoparticles with a Reusable Template–“Plastic Antibodies”

Molecularly imprinted polymers (MIPs) are generic alternatives to antibodies in sensors, diagnostics, and separations. To displace biomolecules without radical changes in infrastructure in device manufacture, MIPs should share their characteristics (solubility, size, specificity and affinity, localized binding domain) whilst maintaining the advantages of MIPs (low‐cost, short development time, and high stability) hence the interest in MIP nanoparticles. Herein, a reusable solid‐phase template approach is reported (fully compatible with automation) for the synthesis of MIP nanoparticles and their precise manufacture using a prototype automated UV photochemical reactor. Batches of nanoparticles (30–400 nm) with narrow size distributions imprinted with: melamine (d = 60 nm, K_d = 6.3 × 10^?8 M ), vancomycin (d = 250 nm, K_d = 3.4 × 10^?9 M ), a peptide (d = 350 nm, K_d = 4.8 × 10^?8 M ) and proteins have been produced. The instrument uses a column packed with glass beads, bearing the template. Process parameters are under computer control, requiring minimal manual intervention. For the first time, the reliable re‐use of molecular templates is demonstrated in the synthesis of MIPs (≥30 batches of nanoMIPs without loss of performance). NanoMIPs are produced template‐free and the solid‐phase acts both as template and affinity separation medium.     

The Fabrication of a Photoresponsive Molecularly Imprinted Polymer for the Photoregulated Uptake and Release of Caffeine

A photoresponsive molecularly imprinted polymer (MIP) material is successfully fabricated from an azobenzene‐based functional monomer, 4‐[(4‐methacryloyloxy)phenylazo]benzoic acid (MPABA), using caffeine as a molecular template. The trans–cis photoisomerization properties of MPABA are retained after incorporation into the rigid 3D crosslinked polymer matrix. Substrate affinity of the MIP receptor sites is photoswitchable. This can be attributed to the photoisomerization of azobenzene chromophores within the MIP receptors, resulting in the alteration of their geometry and the spatial arrangement of their binding functionalities. The favorable binding constant of the MIP receptors for caffeine is 5.48 × 10⁴ M ^–1 in dimethylsulfoxide. The density of the caffeine‐specific receptor sites in the MIP material is 0.95 μmol (g MIP)^–1. Upon irradiation at 365 nm, 58.3 % of receptor‐bound caffeine is released from the MIP material. Subsequent irradiation at 440 nm causes 96.4 % of the released caffeine to be rebound by the MIP material. This near‐quantitative uptake of the released caffeine is evidence of the reversibility of the receptor‐site configuration and substrate affinity during the photoswitching of the azobenzene chromophores. Although the photoregulated substrate release and uptake processes are generally repeatable, a gradual reduction in the extent of substrate release and rebinding is observed. This may be caused by the slow deformation of MIP receptors during the course of repetitive photoswitching. The results of this work demonstrate the potential of stimuli‐responsive MIP materials as smart chemicals and as drug‐delivery systems.     

Zn(II)‐Protoporphyrin IX‐Based Photosensitizer‐Imprinted Au‐Nanoparticle‐Modified Electrodes for Photoelectrochemical Applications

The electropolymerization of thioaniline‐modified Au nanoparticles (NPs) on thioaniline monolayer‐functionalized electrodes in the presence of Zn(II)‐protoporphyrin IX yields bis aniline‐crosslinked Au NPs matrices that include molecular imprinted sites for binding the Zn(II)‐protoporphyrin IX photosensitizer. The binding of the photosensitizer yields photoelectrochemically active electrodes that produce anodic photocurrents in the presence of the electron donor benzohydroquinone. The efficient photocurrents formed in the presence of the imprinted electrode are attributed to the high‐affinity binding of the photosensitizer to the imprinted sites, K_a = 3.2 × 10⁶ m ^?1, and to the effective transport of the photoejected electrons to the bulk electrode via the bridged Au NPs matrix. Similarly, a N,N′‐dialkyl‐4,4′‐bipyridinium‐modified Zn(II)‐protoporphyrin IX photosensitizer‐electron acceptor dyad is imprinted in the bis aniline‐crosslinked Au NPs matrix. The photocurrent generated by the imprinted matrix is approximately twofold higher as compared to the photocurrent generated by the Zn(II)‐protoporphyrin IX‐imprinted Au NPs matrix. The efficient photocurrents generated in the presence of the bipyridinium‐modified Zn(II)‐protoporphyrin IX‐imprinted matrix are attributed to the effective primary charge separation of the electron–hole species in the dyad structure, followed by the effective transport of the photoejected electrons to the electrode via the bis aniline‐crosslinked Au NPs matrix.     

Fluorescence Quenching upon Binding of Copper Ions in Dye‐Doped and Ligand‐Capped Polymer Nanoparticles: A Simple Way to Probe the Dye Accessibility in Nano‐Sized Templates

The synthesis and properties of well‐defined core–shell type fluorescent metal‐chelating polymer nanoparticles NP, in the 15 nm diameter range, with a fluorophore (9,10‐diphenylanthracene: DPA) entrapped in the particle core and a selective ligand (1,4,8,11‐tetraazacyclotetradecane: Cyclam), grafted onto the surface are presented. NPs with different number of dye‐per‐particle are readily obtained by entrapment of the fluorophore within the polymer core. The ligand‐coated NPs exhibit a high affinity for Cu²⁺ ions in aqueous solution and quenching of the DPA fluorescence is observed upon binding of copper. The quenching of fluorescence arises through energy transfer (FRET) from the dye to the copper‐cyclam complexes that form at the NP surface with an operating distance (d) in the 2 nm range. A simple core–shell model accounts for the steady‐state and time‐resolved fluorescence titration experiments: dye molecules located in the outer sphere (thickness d) of the NPs are quenched while the fluorescence of dyes embedded more deeply is not affected by the binding of copper ions. The observed high quenching efficiency (60–65 %), which is tightly correlated to the volumic and microstructural features of the NPs, shed light on the enhanced accessibility inherent in nano‐sized templates. The response towards different metal ions was investigated and this confirmed the selectivity of the nanoparticle template‐assembled sensor for cupric ions.     

Synthesis of Gadolinium‐Labeled Shell‐Crosslinked Nanoparticles for Magnetic Resonance Imaging Applications

Shell‐crosslinked knedel‐like nanoparticles (SCKs; “knedel” is a Polish term for dumplings) were derivatized with gadolinium chelates and studied as robust magnetic‐resonance‐imaging‐active structures with hydrodynamic diameters of 40 ± 3 nm. SCKs possessing an amphiphilic core–shell morphology were produced from the aqueous assembly of diblock copolymers of poly‐(acrylic acid) (PAA) and poly(methyl acrylate) (PMA), PAA₅₂–b–PMA₁₂₈, and subsequent covalent crosslinking by amidation upon reaction with 2,2′‐(ethylenedioxy)bis(ethylamine) throughout the shell layer. The properties of these materials, including non‐toxicity towards mammalian cells, non‐immunogenicity within mice, and capability for polyvalent targeting, make them ideal candidates for utilization within biological systems. The synthesis of SCKs derivatized with Gd^III and designed for potential use as a unique nanometer‐scale contrast agent for MRI applications is described herein. Utilization of an amino‐functionalized diethylenetriaminepentaacetic acid–Gd analogue allowed for direct covalent conjugation throughout the hydrophilic shell layer of the SCKs and served to increase the rotational correlation lifetime of the Gd. In addition, the highly hydrated nature of the shell layer in which the Gd was located allowed for rapid water exchange; thus, the resulting material demonstrated large ionic relaxivities (39 s^–1 mM^–1) in an applied magnetic field of 0.47 T at 40 °C and, as a result of the large loading capacity of the material, also demonstrated high molecular relaxivities (20 000 s^–1 mM^–1).     

Facile Formation of Uniform Shell‐Crosslinked Nanoparticles with Built‐in Functionalities from N‐Hydroxysuccinimide‐Activated Amphiphilic Block Copolymers

An amphiphilic block copolymer, poly(methylacrylate)₈₂‐block‐poly(N‐(acryloyloxy)succinimide_0.29‐co‐(N‐acryloylmorpholine)_0.71)₁₅₅ (PMA₈₂‐b‐P(NAS_0.29‐co‐NAM_0.71)₁₅₅), was synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization and then was supramolecularly assembled into micelles in aqueous solution, followed by chemical crosslinking throughout the shell region upon the introduction of 2,2′‐(ethylenedioxy)‐bis(ethylamine) as a crosslinker to afford well‐defined shell crosslinked nanoparticles (SCKs). The number‐averaged hydrodynamic diameters of the micelles and SCKs were (17 ± 4) nm and (16 ± 3) nm, respectively, by dynamic light scattering (DLS), and (15 ± 2) nm and (13 ± 2) nm, respectively, by transmission electron microscopy (TEM). In an attempt to narrow the particle size distributions, the dodecyl trithiocarbonate chain end of the block copolymer was replaced by a 2‐cyanoisopropyl moiety. Each nanoparticle system was characterized by DLS, electrophoretic light scattering (ELS), TEM, and small‐angle X‐ray scattering (SAXS). SAXS was of particular importance, as it provided definitive observation and quantification of shell contraction and densification upon shell crosslinking. The direct incorporation of NAS into the block copolymers during their preparation allowed for unique crosslinking chemistry to proceed with added diamino crosslinkers. The primary advantages of this system include the ability to conduct in situ synthesis of SCKs that are crosslinked directly and derivatized easily by adding nucleophilic ligands before, during, or after the crosslinking.     

Cover Picture: Synthesis of Gadolinium‐Labeled Shell‐Crosslinked Nanoparticles for Magnetic Resonance Imaging Applications (Adv. Funct. Mater. 8/2005)

Robust, amphiphilic core–shell nanoparticles that are selectively labeled with gadolinium in the hydrophilic and water‐swollen shell layer are depicted in the cover picture. These well‐defined nanostructured materials exhibit high relaxivity, a large loading capacity, and are based upon a biocompatible platform for ultimate function in magnetic resonance imaging (MRI) applications, as reported by Wooley and co‐workers on p. 1248. Shell‐crosslinked knedel‐like nanoparticles (SCKs; “knedel” is a Polish term for dumplings) were derivatized with gadolinium chelates and studied as robust magnetic‐resonance‐imaging‐active structures with hydrodynamic diameters of 40 ± 3 nm. SCKs possessing an amphiphilic core–shell morphology were produced from the aqueous assembly of diblock copolymers of poly‐(acrylic acid) (PAA) and poly(methyl acrylate) (PMA), PAA₅₂–b–PMA₁₂₈, and subsequent covalent crosslinking by amidation upon reaction with 2,2′‐(ethylenedioxy)bis(ethylamine) throughout the shell layer. The properties of these materials, including non‐toxicity towards mammalian cells, non‐immunogenicity within mice, and capability for polyvalent targeting, make them ideal candidates for utilization within biological systems. The synthesis of SCKs derivatized with Gd^III and designed for potential use as a unique nanometer‐scale contrast agent for MRI applications is described herein. Utilization of an amino‐functionalized diethylenetriaminepentaacetic acid–Gd analogue allowed for direct covalent conjugation throughout the hydrophilic shell layer of the SCKs and served to increase the rotational correlation lifetime of the Gd. In addition, the highly hydrated nature of the shell layer in which the Gd was located allowed for rapid water exchange; thus, the resulting material demonstrated large ionic relaxivities (39 s^–1 mM^–1) in an applied magnetic field of 0.47 T at 40 °C and, as a result of the large loading capacity of the material, also demonstrated high molecular relaxivities (20 000 s^–1 mM^–1).     

Understanding the Host–Guest Interaction Between Responsive Core‐Crosslinked Hybrid Nanoparticles of Hyperbranched Poly(ether amine) and Dyes: The Selective Adsorption and Smart Separation of Dyes in Water

The host–guest interaction between polymer nanoparticles and guest molecules plays a key role in fields such as controlled drug delivery, separation, and nanosensors. To understand this host–guest interaction, a series of hybrid polymer nanoparticles (SiO_1.5‐hPEA NPs) are designed and prepared based on hyperbranched poly(ether amine) (hPEA) with the different hydrophobicity and functional groups. Their adsorption behavior to twelve hydrophilic dyes in aqueous solution is studied. The core‐crosslinked hybrid nanoparticles (SiO_1.5‐hPEA NPs) are prepared by direct dispersion of hPEA containing trimethoxysilyl moieties (TMS‐hPEA) in aqueous solution, which exhibit sharp multiresponse to temperature, pH, and ionic strength in aqueous solution. The effect of molecular structure of TMS‐hPEA on the host–guest interaction between SiO_1.5‐hPEA NPs and hydrophilic dyes is investigated in detail. The obtained SiO_1.5‐hPEA NPs interact selectively with different hydrophilic dyes in aqueous solution. The distribution coefficient (K) for partitioning of dyes between SiO_1.5‐hPEA NPs and water is proposed to define the strength of the host‐guest interaction between the nanoparticles and dyes. K increases with the increasing hydrophobicity of the hPEA backbone regardless of their charge states of SiO_1.5‐hPEA NPs and dyes. A methodology is demonstrated for the smart separation of a mixture of dyes in water using SiO_1.5‐hPEA NPs.     

A Molecularly Imprinted Copolymer Designed for Enantioselective Recognition of Glutamic Acid

A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element to fabricate a capacitive sensor for enantioselective recognition of glutamic acid (Glu). The MIP with a well‐defined structure was synthesized on a gold electrode in one step by electrochemical copolymerization of o‐phenylenediamine (o‐PD) and dopamine (DA) in the presence of template molecule Glu. The resulting MIP material was characterized with a potentiostatic frequency scan method, cyclic voltammetry, capacitance measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy. The structure and recognition behaviour of the copolymer film to template molecule depended on its composition. The optimal composition was at the o‐PD to DA molar ratio of 3:2. With a potentiostatic time scan method the copolymer displayed high enantioselectivity and sensitivity to the stereoselective rebinding of L ‐ or D ‐Glu to their corresponding artificial receptor due to the exact definition of the imprint cavity. The capacitance response of the sensor for L ‐Glu or D ‐Glu was proportional to their concentration in the range of 16.7 to 250 μM . The enantiometric selectivity coefficients for L ‐Glu and D ‐Glu imprinted films against their respective enantiomers are 24 and 15, respectively. The resulting MIP capacitive sensors showed good reproducibility, stability and repeatability. This strategy opened a convenient way for preparation of enantioselective MIPs and recognition of enantiotropic molecules.     

Magnetic Molecularly Imprinted Polymer Nanocomposites via Surface‐Initiated RAFT Polymerization

A general protocol to synthesize superparamagnetic molecularly imprinted polymer particles, using a RAFT‐mediated approach, is described. S‐ propranolol‐imprinted composites were obtained by functionalizing commercially available amino‐modified Fe₃O₄ nanoparticles with a trithiocarbonate agent and subsequently by polymerizing thin molecularly imprinted layers. Different parameters were optimized and their effect on both nanomorphology and imprinting behaviour was studied. Optimum conditions allowed the synthesis of 40 nm composite particles with a 7 nm MIP shell, exhibiting superparamagnetic properties and specific molecular recognition of S‐ propranolol. The possibility of fine‐tuning the surface properties of the particles is demonstrated by using the “living” nature of active RAFT fragments present on the surface of the composites to further functionalize the particles with ethylene glycol methacrylate phosphate polymer brushes.     

Selective Artificial Receptors Based on Micropatterned Surface‐Imprinted Polymers for Label‐Free Detection of Proteins by SPR Imaging

A novel concept to generate micropatterned surface‐imprinted polymers (SIPs) for protein recognition by using standard photolithographic technology is introduced. Avidin‐imprinted poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) conducting polymer microbands are prepared directly on surface plasmon resonance (SPR) chips, which enable convenient label‐free monitoring of the binding events. The novel surface‐imprinted microstructures bind avidin, the template protein, with dissociation constants in the submicromolar range (125 nM ). The SIPs have an avidin binding capacity approximately one order of magnitude higher than the corresponding nonimprinted polymers and are able to discriminate among functional homologues of avidin, i.e., neutravidin, extravidin, and streptavidin.     

Preparation and Characterization of Molecularly Imprinted Polymeric Nanoparticles for Atrial Natriuretic Peptide (ANP)

Natriuretic peptide receptor A (NPRA), the receptor for the cardiac hormone atrial natriuretic peptide (ANP), is expressed abundantly on cancer cells and disruption of ANP‐NPRA signaling inhibits tumor burden and metastasis. Since antagonists of NPRA signaling have not provided reproducible results, we reason that a synthetic neutralizing antibody to ANP, which has high selectivity and affinity for ANP, can be used to regulate ANP levels and attenuate NPRA signaling. In this study, we prepare molecularly imprinted polymeric nanoparticles (MIPNPs) for ANP using a short peptide of ANP as the template and determine their binding affinity and selectivity. The MIPNPs are prepared by precipitation polymerization using NH₂–SLRRSS–CONH₂, which is a short peptide from ANP, as a template, methacrylic acid and N‐isopropylacrylamide as functional monomers, and bis‐acrylamide as a crosslinker. The average diameters of the MIPNPs and of non‐imprinted nanoparticles (NIPNPs) in water are 215.8 ± 4.6 nm and 197.7 ± 3.1 nm respectively. The binding‐isotherm analysis shows that the MIPNPs have a much‐higher binding affinity for the template peptide and ANP than the NIPNPs. Scatchard analysis gives an equilibrium dissociation constant, K_d, of 7.3 × 10^?6 M with a binding capacity of 106.7 μmol g^?1 for the template peptide and a K_d of 7.9 × 10^?6 M with a binding capacity of 36.0 μmol g^?1 for the ANP. Measurements of the binding kinetics reveal that MIPNPs reach protein‐adsorption equilibrium in 30 min. The MIPNPs are found to have a high specificity for ANP with little affinity for BSA or scrambled ANP peptide. The MIPNPs also recognize and adsorb ANP in cell‐culture medium spiked with ANP and in human plasma. Taken together, these results indicate that the MIPNPs have a high affinity and selectivity for ANP and can be used as a synthetic antibody for modulating ANP‐NPRA signaling in cancers.     

PbSe/PbS and PbSe/PbSexS1–x Core/Shell Nanocrystals

The synthesis of PbSe/PbS and PbSe/PbSe_xS_1–x core/shell nanocrystals (NCs) with luminescence quantum efficiencies of 45–55 % is reported. PbSe/PbS NCs are prepared via a two‐stage process, while the PbSe/PbSe_xS_1–x NCs are formed in a single‐stage procedure. The core/shell NCs exhibit an energy tuning of the exciton transitions, with respect to that of the core NC, that is dependent on the core diameter, shell thickness, and composition.     

Gel–Liposome‐Mediated Co‐Delivery of Anticancer Membrane‐Associated Proteins and Small‐Molecule Drugs for Enhanced Therapeutic Efficacy

A programmed drug‐delivery system that can transport different anticancer therapeutics to their distinct targets holds vast promise for cancer treatment. Herein, a core–shell‐based “nanodepot” consisting of a liposomal core and a crosslinked‐gel shell (designated Gelipo) is developed for the sequential and site‐specific delivery (SSSD) of tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) and doxorubicin (Dox). As a small‐molecule drug intercalating the nuclear DNA, Dox is loaded in the aqueous core of the liposome, while TRAIL, acting on the death receptor (DR) on the plasma membrane, is encapsulated in the outer shell made of crosslinked hyaluronic acid (HA). The degradation of the HA shell by HAase that is concentrated in the tumor environment results in the rapid extracellular release of TRAIL and subsequent internalization of the liposomes. The parallel activity of TRAIL and Dox show synergistic anticancer efficacy. The half‐maximal inhibitory concentration (IC₅₀) of TRAIL and Dox co‐loaded Gelipo (TRAIL/Dox‐Gelipo) toward human breast cancer (MDA‐MB‐231) cells is 83 ng mL^–1 (Dox concentration), which presents a 5.9‐fold increase in the cytotoxicity compared to 569 ng mL^–1 of Dox‐loaded Gelipo (Dox‐Gelipo). Moreover, with the programmed choreography, Gelipo significantly improves the inhibition of the tumor growth in the MDA‐MB‐231 xenograft tumor animal model.     

Entangled Azobenzene‐Containing Polymers with Photoinduced Reversible Solid‐to‐Liquid Transitions for Healable and Reprocessable Photoactuators

Photoactuators based on liquid crystal elastomers or networks are smart materials that show photoinduced motions. However, their crosslinked networks make their repair or reprocessing difficult. Here, a healable and reprocessable photoactuator is fabricated using entangled high‐molecular‐weight azobenzene‐containing polymers (azopolymers) that are non‐crosslinked. A series of linear liquid crystal azopolymers with different molecular weights are synthesized. The low‐molecular‐weight azopolymers (5–53 kg mol^?1) cannot form freestanding photoactuators because their polymer chains lack entanglements, which makes them hard and brittle. In contrast, flexible and stretchable actuators are fabricated using high‐molecular‐weight azopolymers (80–100 kg mol^?1) that exhibit good processability because of the polymer chain entanglements. The azopolymer photoactuators show photoinduced bending based on photoinduced trans–cis isomerization of the azopolymers on the irradiated side. The experiments show not only photoinduced phase transitions or changes in the order parameters but also photoinduced solid‐to‐liquid transition of the azopolymers resulting in shape changes and mechanical responses. Thus, photoinduced solid‐to‐liquid transition is a new mechanism for the design of photoactuators. Moreover, the azopolymer photoactuators are healable and reprocessable via solution processing or light irradiation. Healability and reprocessability prolong lifetimes of photoactuators are important for materials reusage and recycling, and represent a new strategy for the preparation of smart materials.     

Synthesis of Dumbbell‐Like Gold–Metal Sulfide Core–Shell Nanorods with Largely Enhanced Transverse Plasmon Resonance in Visible Region and Efficiently Improved Photocatalytic Activity

The metallic nanostructures with unique properties of tunable plasmon resonance and large field enhancement have been cooperated with semiconductor to construct hetero‐nanostructures for various applications. Herein, a general and facile approach to synthesize uniform dumbbell‐like gold–sulfide core–shell hetero‐nanostructures is reported. The transformation from Au nanorods (NRs) to dumbbell‐like Au NRs and coating of metal sulfide shells (including Bi₂S₃, CdS, Cu_xS, and ZnS) are achieved in a one‐pot reaction. Due to the reshaping of Au core and the deposition of sulfide shell, the plasmon resonances of Au NRs are highly enhanced, especially the about 2 times enhancement for the visible transverse plasmon resonance compared with the initial Au NRs. Owing to the highly enhanced visible light absorption and strong local electric field, we find the photocatalytic activity of dumbbell‐like Au–Bi₂S₃ NRs is largely enhanced compared with pure Bi₂S₃ and normal Au–Bi₂S₃ NRs by testing the photodegradation rate of Rhodamine B (RhB). Moreover, the second‐layer sulfide can be coated and the double‐shell Au–Bi₂S₃–CdS hetero‐nanostructures show further improved photodegradation rate, especially about 2 times than that of Degussa P25 TiO₂ (P25) ascribing to the optimum band arrangement and then the prolonged lifetime of photo‐generated carriers.     

Highly Stable Colloidal “Giant” Quantum Dots Sensitized Solar Cells

Colloidal quantum dots (QDs) are widely studied due to their promising optoelectronic properties. This study explores the application of specially designed and synthesized “giant” core/shell CdSe/(CdS)_x QDs with variable CdS shell thickness, while keeping the core size at 1.65 nm, as a highly efficient and stable light harvester for QD sensitized solar cells (QDSCs). The comparative study demonstrates that the photovoltaic performance of QDSCs can be significantly enhanced by optimizing the CdS shell thickness. The highest photoconversion efficiency (PCE) of 3.01% is obtained at optimum CdS shell thickness ≈1.96 nm. To further improve the PCE and fully highlight the effect of core/shell QDs interface engineering, a CdSe_x S_1?x interfacial alloyed layer is introduced between CdSe core and CdS shell. The resulting alloyed CdSe/(CdSe_x S_1?x )₅/(CdS)₁ core/shell QD‐based QDSCs yield a maximum PCE of 6.86%, thanks to favorable stepwise electronic band alignment and improved electron transfer rate with the incorporation of CdSe_x S_1?x interfacial layer with respect to CdSe/(CdS)₆ core/shell. In addition, QDSCs based on “giant” core/CdS‐shell or alloyed core/shell QDs exhibit excellent long‐term stability with respect to bare CdSe‐based QDSCs. The giant core/shell QDs interface engineering methodology offers a new path to improve PCE and the long‐term stability of liquid junction QDSCs.     

Synthesis of Inorganic and Organic–Inorganic Hybrid Hollow Particles Using a Cationic Surfactant with a Partially Fluorinated Tail

A new partially fluorinated cationic surfactant, 1‐(10‐perfluorooctyldecyl)pyridinium bromide monohydrate, is synthesized and used as the template for mesoporous ceramic and inorganic–organic hybrid particles. Several hydrolyzed alkoxide precursors are shown to co‐assemble with this surfactant to form hollow vesicle‐like particles, and the effect of changing the alkoxide chemical structure on the formation of these particles is examined. Tetramethoxysilane produces cubic or columnar particles without hollow cavities, but all other tetra‐n‐alkoxysilanes tested up to the n‐butoxide produce hollow particles. As the alkoxide length increases, the shell structure changes from multilayered (with Si(OC₂H₅)₄) to a single thin layer (with Si(OC₃H₇)₄) to a single thick layer (with Si(OC₄H₉)₄). The stability of the fluorocarbon bilayers allows similar vesicular structures to be obtained in organic–inorganic hybrids prepared with bridged alkoxysilanes. Ethylene‐bridged silanes display similar structures to tetraalkoxysilanes. However, the hollow structures appear to partially collapse when the bridging chain is too long (octylene) and no hollow particles are formed with bis(trialkoxysilylpropyl)amines.     

A Low‐Toxic Multifunctional Nanoplatform Based on Cu9S5@mSiO2 Core‐Shell Nanocomposites: Combining Photothermal‐ and Chemotherapies with Infrared Thermal Imaging for Cancer Treatment

Copper chalcogenides have been demonstrated to be a promising photothermal agent due to their high photothermal conversion efficiency, synthetic simplicity, and low cost. However, the hydrophobic and less biocompatible characteristics associated with their synthetic processes hamper widely biological applications. An alternative strategy for improving hydrophilicity and biocompatibility is to coat the copper chalcogenide nanomaterials with silica shell. Herein, the rational preparation design results in successful coating mesoporous silica (mSiO₂) on as‐synthesized Cu₉S₅ nanocrystals, forming Cu₉S₅@mSiO₂‐PEG core‐shell nanostructures. As‐prepared Cu₉S₅@mSiO₂‐PEG core‐shell nanostructures show low cytotoxicity and excellent blood compatibility, and are effectively employed for photothermal ablation of cancer cells and infrared thermal imaging. Moreover, anticancer drug of doxorubicin (DOX)‐loaded Cu₉S₅@mSiO₂‐PEG core‐shell nanostructures show pH sensitive release profile and are therefore beneficial to delivery of DOX into cancer cells for chemotherapy. Importantly, the combination of photothermal‐ and chemotherapies demonstrates better effects of therapy on cancer treatment than individual therapy approaches in vitro and in vivo.