Upconversion nanoparticle-based fluorescence resonance energy transfer sensing of programmed death ligand 1 using sandwich epitope-imprinted polymers.

Programmed death ligand 1 (PD-L1) has been shown to suppress the anti-tumor immune response of some lung cancer patients, and thus PD-L1 expression may be a valuable predictor of the efficacy of anti-PD-1/PD-L1 monoclonal therapy in such patients. In this work, a sandwich approach to fluorescence resonance energy transfer (FRET) was used with green-emitting Yb3+/Ho3+-doped upconversion nanoparticles (UCNPs) and a rhodamine-conjugated conductive polymer as donor and acceptor, respectively. Yb3+/Ho3+-doped UCNPs were synthesized and then coated with poly(ethylene-co-vinyl alcohol), pEVAL, imprinted with PD-L1 peptide. Epitope-imprinted composite nanoparticles were characterized by dynamic light scattering, superconducting quantum interference magnetometry, and atomic force microscopy. Poly(triphenylamine rhodamine-3-acetic acid-co-3,4-ethoxylenedioxythiophene)s copolymers (p(TPAR-co-EDOT)) were imprinted with various epitopes of PD-L1 by in situ electrochemical polymerization. The epitope-imprinted polymer-coated electrodes were then characterized by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Finally, the sandwich sensing of various PD-L1 concentrations with peptide-imprinted p(TPAR-co-EDOT)-coated substrate and UCNP-containing magnetic peptide-imprinted pEVAL nanoparticles by FRET was conducted to measure the concentration of PD-L1 in A549 lung cancer cell lysate.

NIR-Triggered Generation of Reactive Oxygen Species and Photodynamic Therapy Based on Mesoporous Silica-Coated LiYF4 Upconverting Nanoparticles.

To date, the increase in reactive oxygen species (ROS) production for effectual photodynamic therapy (PDT) treatment still remains challenging. In this study, a facile and effective approach is utilized to coat mesoporous silica (mSiO2) shell on the ligand-free upconversion nanoparticles (UCNPs) based on the LiYF4 host material. Two kinds of mesoporous silica-coated UCNPs (UCNP@mSiO2) that display green emission (doped with Ho3+) and red emission (doped with Er3+), respectively, were successfully synthesized and well characterized. Three photosensitizers (PSs), merocyanine 540 (MC 540), rose bengal (RB), and chlorin e6 (Ce6), with the function of absorption of green or red emission, were selected and loaded into the mSiO2 shell of both UCNP@mSiO2 nanomaterials. A comprehensive study for the three UCNP@mSiO2/PS donor/acceptor pairs was performed to investigate the efficacy of fluorescence resonance energy transfer (FRET), ROS generation, and in vitro PDT using a MCF-7 cell line. ROS generation detection showed that as compared to the oleate-capped and ligand-free UCNP/PS pairs, the UCNP@mSiO2/PS nanocarrier system demonstrated more pronounced ROS generation due to the UCNP@mSiO2 nanoparticles in close vicinity to PS molecules and a higher loading capacity of the photosensitizer. As a result, the three LiYF4 UCNP@mSiO2/PS nanoplatforms displayed more prominent therapeutic efficacies in PDT by using in vitro cytotoxicity tests.

Embedded Upconversion Nanoparticles in Magnetic Molecularly Imprinted Polymers for Photodynamic Therapy of Hepatocellular Carcinoma.

In this work, high-temperature pyrolysis was used to prepare both the core and shell of lantha-nide-doped UCNPs with lithium yttrium tetrafluoride (LiYF4) to enhance the green luminescence. Merocyanine 540 (MC540)-grafted magnetic nanoparticles were incorporated in the PD-L1 pep-tide-imprinted poly(ethylene-co-vinyl alcohol) particles, which were formed by precipitation in a non-solvent. UCNPs in the non-solvent bath were thus entrapped in the imprinted particles to generate composite nanoparticles for the targeting and photodynamic therapy of PD-L1 in tumor cells. Finally, the in vitro cytotoxicity of the nanoparticles in HepG2 human liver cancer cells was evaluated with the continuous administration of MC540/MNPs@MIPs/UCNPs under irradiation by an NIR laser. To understand the delivery of the UCNP-embedded molecularly imprinted pol-ymers, the intrinsic and extrinsic pathways were also investigated.

Upconversion Nanoparticles Encapsulated with Molecularly Imprinted Amphiphilic Copolymer as a Fluorescent Probe for Specific Biorecognition.

A fluorescent probe for specific biorecognition was prepared by a facile method in which amphiphilic random copolymers were encapsulated with hydrophobic upconversion nanoparticles (UCNPs). This method quickly converted the hydrophobic UCNPs to hydrophilic UNCPs. Moreover, the self-folding ability of the amphiphilic copolymers allowed the formation of molecular imprinting polymers with template-shaped cavities. LiYF4:Yb3+/Tm3+@LiYF4:Yb3+ UCNP with up-conversion emission in the visible light region was prepared; this step was followed by the synthesis of an amphiphilic random copolymer, poly(methacrylate acid-co-octadecene) (poly(MAA-co-OD)). Combining the UCNPs and poly(MAA-co-OD) with the templates afforded a micelle-like structure. After removing the templates, UCNPs encapsulated with the molecularly imprinted polymer (MIP) (UCNPs@MIP) were obtained. The adsorption capacities of UCNPs@MIP bound with albumin and hemoglobin, respectively, were compared. The results showed that albumin was more easily bound to UCNPs@MIP than to hemoglobin because of the effect of protein conformation. The feasibility of using UCNPs@MIP as a fluorescent probe was also studied. The results showed that the fluorescence was quenched when hemoglobin was adsorbed on UCNPs@MIP; however, this was not observed for albumin. This fluorescence quenching is attributed to Förster resonance energy transfer (FRET) and overlap of the absorption spectrum of hemoglobin with the fluorescence spectrum of UCNPs@MIP. To our knowledge, the encapsulation approach for fabricating the UCNPs@MIP nanocomposite, which was further used as a fluorescent probe, might be the first report on specific biorecognition.

Synthesis of Multifunctional Nanoparticles for the Combination of Photodynamic Therapy and Immunotherapy.

Programmed death-ligand 1 protein (PD-L1) has been posited to have a major role in suppressing the immune system during pregnancy, tissue allografts, autoimmune disease and other diseases, such as hepatitis. Photodynamic therapy uses light and a photosensitizer to generate singlet oxygen, which causes cell death (phototoxicity). In this work, photosensitizers (such as merocyanine) were immobilized on the surface of magnetic nanoparticles. One peptide sequence from PD-L1 was used as the template and imprinted onto poly(ethylene-co-vinyl alcohol) to generate magnetic composite nanoparticles for the targeting of PD-L1 on tumor cells. These nanoparticles were characterized using dynamic light scattering, high-performance liquid chromatography, Brunauer-Emmett-Teller analysis and superconducting quantum interference magnetometry. Natural killer-92 cells were added to these composite nanoparticles, which were then incubated with human hepatoma (HepG2) cells and illuminated with visible light for various periods. The viability and apoptosis pathway of HepG2 were examined using a cell counting kit-8 and quantitative real-time polymerase chain reaction. Finally, treatment with composite nanoparticles and irradiation of light was performed using an animal xenograft model.

Synthesis, Optical Properties, and Sensing Applications of LaF3:Yb3+/Er3+/Ho3+/Tm3+ Upconversion Nanoparticles.

Herein, we successfully synthesized a series of LaF3:Yb3+/Er3+/Ho3+/Tm3+ upconversion nanoparticles (UCNPs) and LaF3:Yb3+0.20, Er3+0.02@LaF3:Yb3+0.20 core/shell UCNPs by modifying the amount of NaOH and the reaction time. Hexagonal LaF3 nanocrystals with uniform particle sizes and bright UC emissions were obtained. The crystal structures of the lanthanide-doped LaF3 UCNPs were investigated using wide-angle X-ray diffraction. The morphologies and particle sizes of the nanocrystals were determined using transmission electron microscopy. The photoluminescence (PL) spectra of the LaF3 nanocrystals could be tuned by altering the doping ratio of Er3+, Ho3+, and Tm3+. In addition, the PL intensities increased after coating the UCNP cores with an active shell. The fluorescence intensities of the UCNPs synthesized via a one-hour reaction with the addition of 2.5 or 5 mmol NaOH increased by up to 17 times compared with the sample prepared without the addition of NaOH. By modifying the doping ratio of Yb/Tm, UV-emissive LaF3 nanocrystals were obtained. After surface modification by ligand exchange, the hydrophobic LaF3:Yb3+0.20, Er3+0.02@LaF3:Yb3+0.20 core/shell UCNPs became water-dispersible. These colloid UCNPs could be utilized as a fluorescent probe for the detection of Hg2+ ions under 980 nm near-infrared irradiation.

Interaction of LiYF4:Yb3+/Er3+/Ho3+/Tm3+@LiYF4:Yb3+ upconversion nanoparticles, molecularly imprinted polymers, and templates.

In this work, LiYF4:Yb0.25 3+/Er0.01 3+/Tm0.01 3+/Ho0.01 3+@LiYF4:Yb0.2 3+ upconverting nanoparticles (UCNP) were used as luminescent materials for the preparation of molecular imprinting polymer nanocomposites. Three luminescent molecularly imprinted polymer (MIP) nanocomposites were prepared by in situ polymerization. The relationship between the functional monomers, templates, and upconversion nanoparticles was investigated. Two hydrophilic monomers (acrylic acid (AA) and acrylamide (AAm)) and one hydrophobic monomer (N-tert-butylacrylamide (TBAm)) were employed as functional monomers, while one amino acid (cysteine) and two proteins (albumin and hemoglobin) were employed as the templates to investigate the effect of their interaction with LiYF4:Yb3+/Er3+/Ho3+/Tm3+@LiYF4:Yb3+ core/shell UCNPs on the polymerization process, luminescence properties, and adsorption capacity. The results showed that the UCNPs were embedded in the polymeric matrix to form an irregular quasimicrospherical UCNPs@MIP with diameters ranging from several hundred nanometers to several micrometers depending on the functional monomer. The quenching effect was more pronounced for the adsorption of hemoglobin with UCNPs@MIP compared to cysteine and albumin. In addition, the adsorption capacities of the AA- and AAm-made UCNPs@MIP were greater than those of TBAm-made UCNPs@MIP. The rebinding of the templates onto UCNPs@MIP was very fast and approached equilibrium within 30 min, indicating that the synthesized UCNPs@MIP can be employed as fluorescent probes to offer rapid detection of molecules.

Quantum Dot-Acrylic Acrylate Oligomer Hybrid Films for Stable White Light-Emitting Diodes.

White light-emitting diodes (LEDs) have been achieved using photopolymerization. Red and green CdSe/ZnS core-shell quantum dots (QDs) are dispersed in photopolymerized aliphatic acrylic acrylate resins, cured by using 36 W UV light for 1.5 min producing QD-acrylate nanocomposites, and then a hybrid LED device is achieved using the QD-acrylate nanocomposite with two emission wavelengths excited by using a blue InGaN LED chip. The cured QD-acrylate nanocomposite films are characterized by using ultraviolet-visible, fluorescence, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis measurements. Photopolymerization is conveniently employed to adjust several parameters of the CIE-1931 coordinate (x, y), color temperature, and color rending index (CRI). Good white balance of the red-green hybrid device achieves a luminance of 7976 lm/m2 at a 30 mA working current. The light emission efficiency, CRI, and color temperature of 14%, 47, and 11 204 K, respectively, are attained at this working current.

Dual Stimuli-Responsive Block Copolymers for Controlled Release Triggered by Upconversion Luminescence or Temperature Variation.

An amphiphilic block copolymer (BCP) which contains both photoresponsive and thermoresponsive blocks was synthesized by the atom transfer radical polymerization approach. Meanwhile, a new core/shell type of the upconversion nanoparticle (UCNP) LiYF4:Yb3+ 0.25,Tm3+ 0.01@LiYF4:Yb3+ 0.2 was successfully synthesized. By encapsulating UCNPs inside the micelles of the BCP and incorporating Nile red (NR) into the UCNP@BCP hybrid nanoparticles as a model drug, controlled release of the drug by the dual-stimuli BCP could be studied. After exposing the UCNP-loaded micellar solution to near-infrared (NIR) light, it was found that the UV light pumped from UCNPs could disrupt the polymer micelles and the fluorescence intensity of NR decreased with the increase of the irradiation time of the NIR light. The thermoresponsive study indicated that the fluorescence intensity of NR decreased with the increase of temperature of the micellar solution because of the release of NR into water arising from the contraction of the amphiphilic BCP.

Enhanced Supercapacitor Performance Using Electropolymerization of Self-Doped Polyaniline on Carbon Film.

In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid (SAN) comonomers in solution. Here, SAN acts in dual roles of a self-doped monomer while it also provides an acidic environment which is suitable for electropolymerization. The performance of SPANI-CNP-based supercapacitors significantly depends upon the mole ratio of AN/SAN. Supercapacitor performance was investigated by using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). The optimal performance of SPANI-CNP-based supercapacitor exists at AN/SAN ratio of 1.0, having the specific capacitance of 273.3 Fg-1 at the charging current density of 0.5 Ag-1.

Crosslinked Polymer Ionic Liquid/Ionic Liquid Blends Prepared by Photopolymerization as Solid-State Electrolytes in Supercapacitors.

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br- in PIL-M-(Br) and TFSI- in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br- and TFSI-, respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g-¹, 40 and 48 kW·kg-¹, and 107 and 59.9 Wh·kg-¹ were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively.

Synthesis and characterization of CdS x Se1-x alloy quantum dots with composition-dependent band gaps and paramagnetic properties.

Ternary CdS x Se1-x alloy quantum dots (QDs) and CdS x Se1-x /ZnS core/shell nanocrystals exhibiting composition dependent band gaps have been successfully synthesized. The ZnS shell was doped with 0.1% and 5% of paramagnetic manganese ions so as to be used as a fluorescent/paramagnetic bi-functional probe. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of Cd, S, and Se in CdS x Se1-x nanocrystals with the atomic ratios of Cd, S, and Se which are well consistent with our synthetic ratios. Wide angle X-ray diffraction (WAXD) indicated that the crystal structures of the CdS x Se1-x core QDs and CdS x Se1-x /ZnS core/shell QDs were zinc blende phases. Both dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that the as-synthesized nanocrystals had a narrow size distribution and high crystallinity. The band gaps of CdS x Se1-x nanocrystals were adjustable by varying the ratio of S:Se in the CdS x Se1-x core and were in the range of 1.96 eV to 2.32 eV. Hence, when composition x was changed from 0 to 1, the fluorescence color of the nanocrystals varied from red to green. After shell coverage, the ternary alloy QDs exhibited a superior photoluminescence (PL) quantum yield up to 57%. In comparison with the alloy core QDs, the PL emission peaks of the CdS x Se1-x /ZnS core/shell QDs displayed a small redshift. Electron paramagnetic resonance (EPR) measurements for manganese-doped CdS x Se1-x /ZnS nanocrystals revealed paramagnetic properties for both low and high Mn2+ doping levels.

High Refractive Organic-Inorganic Hybrid Films Prepared by Low Water Sol-Gel and UV-Irradiation Processes.

Organic-inorganic hybrid sols (Ti-O-Si precursor) were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti-O-Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA) to perform photo-polymerization by ultraviolet (UV) irradiation. Results show that the film transparency of poly(Ti-O-Si precursor-co-OPPEA) film is higher than that of a pure poly(Ti-O-Si precursor) film, and that this poly(Ti-O-Si precursor-co-OPPEA) hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n) of 1.83 corresponding to a thickness of 2.59 µm.

Sonochemical synthesis and shape change of colloidal CdSe nanocrystals by high-intensity ultrasound.

In this article, we have developed the synthesis of CdSe nanocrystals by the introduction of high-intensity ultrasound combined with an anionic surfactant (sodium dodecyl sulfate, SDS). TEM, XRD, and SEM EDS confirmed the successful synthesis of CdSe nanoparticles with zinc blende crystal phase. UV, PL, and TEM revealed that large particles settled to the bottom of the reaction flask. In the lower part precipitate, nanorods of different aspect ratios were also observed. The CdSe nanorods were formed by self-assembly due to the SDS surfactant and high-intensity ultrasound. A three-stage mechanism for the synthesis of CdSe nanorods was proposed. The effect of SDS concentration on the shape of nanorods was also investigated. At medium concentrations of SDS (0.2 M), one-dimensional CdSe nanorods with different aspect ratios were obtained. When using low concentrations of SDS (0.1 M), two-dimensional square-like crystals were observed due to all growth crystal faces having roughly the same surface energy.

Synthesis of CdSe-Poly(N-vinylcarbazole) Nanocomposite by Atom Transfer Radical Polymerization for Potential Optoelectronic Applications.

A hybrid inorganic-polymer nanocomposite using CdSe nanocrystals with high electron mobility has been successfully synthesized by atom transfer radical polymerization (ATRP). First the hydroxyl-coated CdSe nanoparticles (i.e., CdSe-OH) were prepared via a wet chemical route. A polymerization initiator was then prepared for ATRP of N-vinylcarbazole. FT-IR, (1) H NMR, and XRD analyses confirmed the successful synthesis of CdSe-poly(N-vinylcarbazole) (PVK) nanohybrid. UV-Vis spectra and photoluminescence data revealed that grafting of PVK onto the surface of CdSe nanocrystals would reduce the band gap of PVK and cause the red shift of emission peak. TEM and SEM micrographs exhibited CdSe nanoparticles that were well-coated with PVK polymer.