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Active packaging films have emerged as alternatives to replace petroleum-based packaging materials. In this work, poly(vinyl alcohol) (PVA)/starch/ethyl lauroyl arginate (LAE) films possessing enhanced properties were prepared. Scanning electron microscopy (SEM) showed that PVA and starch were compatible, the concentrations of LAE greatly affected the structural integrity. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction showed that the inclusion of LAE did not significantly affect the intermolecular interactions and crystal structures of the polymer matrix. With an increase of the LAE content, the tensile strength (TS) was slightly decreased due to the altered microstructures, the elongation at break (EB) significantly increased ascribed to the synergistic effect of acetic acid, glycerol and LAE. The values of TS and EB were 17.25 MPa and 586.08%, respectively when LAE was 10%. Active films showed good barrier properties from UV while retaining the transmittance in the visible light region. The films containing 1% of LAE exhibited antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the inhibition zone of bacterial growth gradually expanded with increasing LAE content. This study demonstrates the potential of using LAE as the antibacterial agent for synthesizing natural-based polymeric films for active packaging applications.

This review is intended to provide an overview of the design and fabrication of ionic liquid-based ionic electroactive polymer (IL-iEAP) transducers for advanced applications in biological and electronic fields. The iEAP is a class of smart materials that can perform sensing or actuating functions by controlling the movement of cations and anions in the active layer. This type of material can deform under low voltage stimulation and generate electrical signals when undergoing mechanical deformation because of ion redistribution. Numerous research attention has been focused on studying the deformation mechanisms and the potential for actuation, sensing, and energy harvesting applications. Compared to the traditional water-based iEAP, the non-volatile IL-iEAP delivers a wider electrochemical window and a more stable actuation performance. In this paper, the classification of iEAP with different actuation mechanisms is first outlined, followed by introducing various preparation methods including nanotechnology for IL-iEAPs, and discussing the key factors governing their actuation performance. In addition, the advanced functions of IL-iEAP in actuating and sensing, especially self-sensing in bionics and electromechanical equipment applications, are reviewed. Finally, novel nanotechnologies used for fabricating IL-iEAPs and the prospects of their microelectromechanical system (MEMS) applications are discussed.

UV protection and coatings for plastics are important in many applications. The cladding of low microwave (MW) absorption composite coatings on high MW transparent plastic substrates is a challenge due to their disparate dielectric properties. Moreover, an uneven heat energy conversion within the composite creates an additional hurdle in producing a coating with good surface integrity. In this study, a protocol was developed to overcome these difficulties based on a hybrid approach. The adverse effect of temperature mismatch between the coating and substrate was reduced through a two-way susceptor-aided heating mechanism. Low MW absorbing sol–gel derived composite coatings consisting of silicon dioxide (SiO2) and titanium dioxide (TiO2) were successfully cladded on the surface of MW and visual light transparent polycarbonate to produce a clear protective coating with UV-resistance. Nanoindentation tests were conducted to assess the effectiveness of the proposed protocol. Significant enhancement in the surface elastic modulus and hardness were achieved.

Open in a separate window Size- and shape-dependent features of plasmonic nanocrystals govern the development of their applications. In the past decades, gold nanostructures, such as gold nanorods and nanoshells, have been well studied and applied for sensing, bioimaging, and photothermal generation. However, knowledge of copper chalcogenide, a new generation of plasmonic nanomaterials, is limited, especially about their preparation and size- and shape-dependent photothermal properties. In this work, controllable size and shape Cu2–xS nanocrystals (NCs) are synthesized by a facile aqueous route. Using low-molecular-weight polyethylenimine (PEI) as the reducing and capping agents, the size and shape of Cu2–xS NCs can be controlled with lengths from 6.5 to 46.5 nm and the aspect ratio from 2.2 to 7.5 by adjusting the concentration of PEI. The plasmonic peak of Cu2–xS experiences a redshift (from 1145 to 1369 nm) when the length increases from 6.5 to 44.5 nm. Under the irradiation of 1064 nm laser with 1.33 W/cm2, an excellent photothermal conversion rate (from 34.9 to 49.0%) is obtained. The characterization of Cu2–xS NCs is conducted with a UV–vis spectrometer, transmission electron microscopy, powder X-ray diffraction measurements, and 1064 nm laser.

Four-dimensional (4D) printable light-powered materials have emerged as a new generation of materials for the development of functional devices. The design of these types of materials is mostly based on the trans-cis transformation of azobenzene moieties in a liquid crystalline elastomer (LCE) matrix, in which the motion is triggered by ultraviolet (UV) irradiation. In this paper, we first report on a direct laser printable photoresist for producing light-powered 4D structures with enhanced mechanical properties and near-infrared (NIR) responsive mechanical deformation. The reported nanocomposite design is based on the photothermal effects of gold nanorods (AuNRs), which can induce the nematic-to-isotropic transition of LCE upon exposure to NIR irradiation. The miscibility between AuNRs and LCE is enhanced by thiol functionalization. Appropriate printing parameters are determined, and nanocomposites containing 0-3 wt % of AuNR loading are fabricated via femtosecond two-photon direct laser writing. The effects of the AuNR loading fraction and laser power on the light-powered actuating performance are evaluated. It is found that the nanocomposite with AuNR loading of 3 wt % demonstrates the maximum percentage (20%) of elongation under an NIR laser power of 2 W. An increase in laser power can lead to faster deformation but slower restoration. The nanocomposites demonstrate relatively good stability. Even after 300 actuation cycles, 80% of the elongation magnitude can be retained. In addition, an improvement of 80% in the complex modulus of the nanocomposites, due to the inclusion of AuNRs, is observed.

With the ever-growing demand in fresh water supply, great efforts have been devoted to developing sustainable systems which could generate fresh water continuously. Solar vapor generation is one of the promising strategies which comprise an unlimited energy source and efficient solar-to-heat generators for overcoming fresh water scarcity. However, current solar vapor generation systems suffer either from inefficient utilization of solar energy or an expensive fabrication process. In this paper, we introduced a nano-plasmonic approach, i.e., a floatable nanocompoiste where copper sulfide nanorods (Cu2-xS NRs) are embedded in a polyvinyl alcohol (PVA) matrix, for solar-to-vapor generation. A high solar vapor generation efficiency of ~87% and water evaporation rate of 1.270 kg m&minus, 2 h&minus, 1 were achieved under simulated solar irradiation of 1 sun. With the illumination of natural daylight, seawater was purified using Cu2-xS NRs-PVA gel, with high purity, as distilled drinking water. The plasmonic nanocomposites demonstrated here are easy to fabricate and highly efficient for solar vapor generation, illustrating a potential solution for future seawater desalination.

In this study, dual-responsive polymeric nanocapsules, in which the state (swelling or collapse) can be repeatedly controlled by external stimuli (i.e., temperature and light), have been designed and prepared through distillation–precipitation polymerization. Temperature sensitive monomers of N-isopropylacrylamide are cross-linked by photoresponsive bis(methacryloylamino) onto a silica nanospherical template to form a core–shell (SiO2–PNIPAM/Azo) structure. The silica core is then removed by hydrofluoric acid to produce PNIPAM/Azo nanocapsules (P/ANCs) of diameter ∼238 nm at ∼25 °C. The size of the nanocapsule is temperature responsive and, as such, its diameter could be reduced to ∼182 nm on increasing the temperature to 40 °C. In addition, the permeability of nanocapsules can be adjusted by UV irradiation. The cis–trans transformation of modified azobenzene allowed us to perform both the encapsulation and controlled release of molecules. Rhodamine B (RhB) was successfully encapsulated using the photomec...

Pickering emulsion, in which the oil–water emulsion interface is stabilised by colloids, has emerged as a promising approach for the preparation of drug delivery systems in the biomedical field. In this study, Pickering emulsion and solvent evaporation were incorporated with high-intensity ultrasonication to successfully fabricate biodegradable poly(lactic-co-glycolic acid) (PLGA)–chitosan core-shell nanocomposites (PLGA-CS) with a narrow size distribution. Our strategy was based on using aqueous-phase chitosan colloids to stabilise the hydrophobic PLGA core without the addition of molecular surfactants or chemical cross-linkers. The use of high-intensity ultrasonication was found to facilitate the efficient dispersion of emulsion droplets so that the particle size of PLGA-CS (255.1–824.8 nm) could be controlled with the application of different amplitudes. A low amplitude (20% of total power) enables the formation of drug-loaded PLGA-CS with a small diameter (255.1 nm) and a high level of monodispersity (polydispersity index, 0.078). The PLGA core allows hydrophobic drugs to be loaded and is encapsulated in a chitosan shell that offers two functions: (i) dispersion of PLGA in an aqueous solution and (ii) modulation of in vitro drug release. Our results reveal that the modified strategy shows promise for the design and preparation of monodisperse polymer-based drug carriers.

In this paper, a miniature fluidic synthesis platform utilizing millimeter dimension channels for the synthesis of cadmium sulfide (CdS) quantum dots and nanocrystals is demonstrated. Traditional nanoparticle synthesis techniques involve macroscopic flasks where reaction conditions may vary at different positions inside the vessel. Therefore challenges in terms of batch reproducibility for large scale production are of great concern. Here, we show that it is possible to replicate reaction conditions so as to produce nanoparticles with similar optical characteristics across different batches using the same reaction parameters. Particle size control was established by varying the flow rate of the precursors, yielding gradually increasing nanocrystal sizes from 2.4 nm to 3.7 nm with increasing residence time. The as-synthesized CdS nanoparticles exhibited tunable photoluminescence by adjusting the molar ratio of the cadmium and sulfur precursors, giving rise to greenish-blue and orange-red emissions under ultraviolet light illumination. The particles were then studied and characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) absorbance, photoluminescence, X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques. Lastly, bioimaging of RAW264.7 mice macrophage cells using ligand exchanged CdS nanoparticles is presented.

Geopolymers have emerged as a promising alternative to ordinary cement due to their attractive physical and thermal properties. The typical compressive strength of geopolymers and their composites is usually limited to around 80 MPa, therefore they should be further strengthened for wider applications, such as ultrahigh strength concrete and bone replacement. This paper presents a facile method for enhancing the compressive strength by incorporating silicon carbide particles (SiCp) and silicon carbide whiskers (SiCw) into a geopolymer matrix via the geopolymerization of metakaolin (MK). The effects of the reinforcement of SiCp and SiCw on the microstructure, thermal properties and compressive properties of the composites were investigated. The SEM images showed that both SiCp and SiCw were well dispersed in the geopolymer matrix. Due to the bridging effect among the SiCw particles, the silicon carbide whisker/geopolymer (SiCw/GP) composites possessed higher porosity and lower density, and thus lower thermal stability and thermal conductivity as compared with the silicon carbide particle/geopolymer (SiCp/GP). The mechanical tests showed that the compressive strength of SiCp/GP composites increased with the increase of SiCp concentration. With an optimum concentration of 10 wt % of SiCp, the compressive strength of the composite was enhanced to 155 MPa, corresponding to a 100% increase as compared with the unfilled geopolymer.

In the past, plasmonics were always referred to as the collective oscillation of free electrons on metal surfaces such as gold (Au) and silver (Ag). This changed when plasmonic behaviour was experimentally demonstrated in semiconductors, i.e. self-doped copper sulfur, nanocrystals (Cu2−xS NCs) in 2009. In fact, Cu2−xS NC possesses different plasmonic behaviour than Au and Ag, in which the resonant condition is governed by another regime (free holes as the carriers) and its sensing capability has not yet been fully explored. In this contribution, the as-prepared (organic phase) Cu2−xS NCs were transferred in water and were tested with glycerin-water mixtures and anions. The results showed that Cu2−xS NC is very sensitive to the variation of refractive index in the surrounding environment. Furthermore, it was found that the plasmonic properties of these NCs are also very sensitive to the presence of anions. By taking the advantages of this “additional” effect, Cu2−xS NC can be used as a potential su...

Remarkable progress has been made on the use of polymer electrolyte membranes (PEMs) for renewable-energy-related research. In particular, carbon nanotubes (CNTs) have emerged as versatile nanomaterials to modify PEMs. However, the inert ionic conduction ability and possible short-circuiting risk are the two major obstacles to their further development. In this work, CNTs are firstly functionalized with an inorganic proton conductor, boron phosphate (BPO 4 ), using a facile polydopamine-assisted sol-gel method to yield BPO 4 @CNTs. This new additive is then used to modify sulfonated poly(ether ether ketone) (SPEEK). Polydopamine coating layer can act as an extraordinary glue to homogeneously adhere BPO 4 nanoparticles on CNTs, thereby not only reducing the risk of short-circuiting, but also fabricating new proton-conducting pathways in the composite membranes. A comprehensive characterization reveals that the thermal stability, tensile properties, and dimensional stability of PEMs are significantly improved. Compared with pure SPEEK, the proton conductivity of SPEEK/BPO 4 @CNTs-2 is improved by 45% and 150% at 20 °C and at 80 °C, respectively. Furthermore, the H 2 /O 2 cell performance of SPEEK/BPO 4 @CNTs-2 membrane exhibits a peak power density of 340.7 mW cm −2 at 70 °C, which is significantly better than that of pure SPEEK (254.2 mW cm −2 ), demonstrating the great potential of proton conductors-functionalized CNTs in PEMs.

Microwave irradiation has been proven to be an effective heating source in synthetic chemistry, and can accelerate the reaction rate, provide more uniform heating and help in developing better synthetic routes for the fabrication of bone-grafting implant materials. In this study, a new technique, which comprises microwave heating and powder metallurgy for in situ synthesis of Ti/CaP composites by using Ti powders, calcium carbonate (CaCO 3 ) powders and dicalcium phosphate dihydrate (CaHPO 4 ·2H 2 O) powders, has been developed. Three different compositions of Ti:CaCO 3 :CaHPO 4 ·2H 2 O powdered mixture were employed to investigate the effect of the starting atomic ratio of the CaCO 3 to CaHPO 4 ·2H 2 O on the phase, microstructural formation and compressive properties of the microwave synthesized composites. When the starting atomic ratio reaches 1.67, composites containing mainly alpha-titanium ( α -Ti), hydroxyapatite (HA), beta-tricalcium phosphate ( β -TCP) and calcium titanate (CaTiO 3 ) with porosity of 26%, pore size up to 152 μm, compressive strength of 212 MPa and compressive modulus of 12 GPa were formed. The in vitro apatite-forming capability of the composite was evaluated by immersing the composite into a simulated body fluid (SBF) for up to 14 days. The results showed that biodissolution occurred, followed by apatite precipitation after immersion in the SBF, suggesting that the composites are suitable for bone implant applications as apatite is an essential intermediate layer for bone cells attachment. The quantity and size of the apatite globules increased over the immersion time. After 14 days of immersion, the composite surface was fully covered by an apatite layer with a Ca/P atomic ratio approximately of 1.68, which is similar to the bone-like apatite appearing in human hard tissue. The results suggested that the microwave assisted- in situ synthesis technique can be used as an alternative to traditional powder metallurgy for the fabrication of Ti/CaP biocomposites.

Stretchable conductive hydrogels have received significant attention due to their possibility of being utilized in wearable electronics and healthcare devices. In this work, a semi-interpenetrating polymer network (SIPN) strategy was employed to fabricate a set of flexible, stretchable and conductive composite hydrogels composed of polyvinyl alcohol (PVA) in the presence of glutaraldehyde as the crosslinker, HCl as the catalyst and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) as the conductive medium. The results from FTIR, Raman, SEM and TGA indicate that a chemical crosslinking network and interactions of PVA and PEDOT:PSS exist in the SIPN hydrogels. The swelling ratio of hydrogels decreased with increasing content of PEDOT:PSS. Due to the chemical crosslinking network and interactions of PVA and PEDOT:PSS, PVA networks semi-interpenetrated with PEDOT:PSS exhibited excellent tensile and compression properties. The tensile strength and elongation at breakage of the composite hydrogels with 0.14 wt% PEDOT:PSS were 70 KPa and 239%, respectively. The compression stress of the composite hydrogels with 0.14 wt% PEDOT:PSS at a strain of 50% was about 216 KPa. The electrical conductivity of the hydrogels increased with increasing PEDOT:PSS content. The flexible, stretchable and conductive properties endow the composite hydrogel sensor with a superior gauge factor of up to 4.4 (strain: 100%). Coupling the strain sensing capability to the flexibility, good mechanical properties and high electrical conductivity, we consider that the designed PVA/PEDOT:PSS composite hydrogels have promising applications in wearable devices, such as flexible electronic skin and sensitive strain sensors.

The extrudate swell ratios of polypropylene (PP) composite melts filled with graphene nano-platelets (GNPs) were measured using a capillary rheometer within a temperature range of 180–230 °C and apparent shear rate varying from 100 to 4000 s−1 in order to identify the effects of the filler content and test conditions on the melt die-swell behavior. It was found that the values of the extrudate swell ratio of the composites increased with increasing apparent shear rate, with the correlation between them obeying a power law relationship, while the values of the extrudate swell ratio decreased almost linearly with rise in temperature. The values of the melt extrudate swell ratio increased approximately linearly with increasing shear stress, and decreased roughly linearly with an increase of the GNP weight fraction. In addition, the extrudate swell mechanisms are discussed from the observation of the fracture surface of the extrudate using scanning electronic microscopy. This study provides a basis for further development of graphene reinforced polymer composites with desirable mechanical performance and good damage resistance.

In this paper, a new method for preparing hyaluronic acid-quantum dot (HA-QD) nanohybrids, which are highly monodispersed, colloidally stable, glutathione (GSH)-responsive and size tunable from 80-500 nm, is reported. Due to the fact that HA is a naturally exist polymer and many types of cancer cells are overexpressed with HA receptors on their surfaces, HA has become one of the promising materials to prepare nanocarriers for theranostics applications. Our design is based on the disulfide chemical structure of cystamine dihydrochloride which has been served as the crosslinker. HA-QDs were synthesized in the nano-cavities created by the microemulsion system. The prepared HA-QDs are GSH-responsive. In the presence of GSH, the disulfide bonds can be cleaved and it leads to the degradation of HA-QDs into smaller fragments. Our in vitro studies show that the HA-QDs are highly specific to the pancreatic and cervix cancer cells and no toxicity was detected in the cell proliferation (MTS) assays, revealing the great potentials to use HA-based nanohybrids for cancer imaging and therapy.

To achieve high precision and efficacy in disease treatment, biodegradability and environmental responsivity are highly desired in drug delivery systems. Having a polylactide (PLA)-based biodegradable scaffold conjugated with doxorubicin (DOX) moieties via pH-responsive linkages, a brush polymer–drug conjugate (BPDC) was synthesized and studied. The biodegradable scaffold, PLA-graft-aldehyde/polyethylene glycol (PLA-g-ALD/PEG), was prepared via a copper-catalyzed alkyne–azide click reaction. Subsequently, the BPDC was obtained by conjugating doxorubicin with the scaffold through an acid-sensitive Schiff base linkage. The well-controlled structures of the resulting BPDC and its precursors were verified by proton nuclear magnetic resonance and gel permeation chromatography characterization. As revealed by dynamic light scattering and transmission electron microscopy, the BPDC had a well-defined nanostructure with the size of 10–30 nm. A drug release study of the BPDC demonstrated a much faster release of DOX at the pH of 5.5 than at the pH of 7.4. Both cell internalization and cytotoxicity studies of the BPDC in MCF-7 breast cancer cells indicated its significant potential for application as a novel anticancer nanomedicine.

The development of shape memory polymers (SMPs) has gained remarkable attention due to their wide range of applications, from biomedical to electromechanical. In this work, we have developed and optimized an electroactive SMP based on polyvinyl alcohol/multi-walled carbon nanotubes (PVA/MWNTs) composites. When a constant voltage of 60 V was applied to the optimized sample, the polymer shape could be recovered to the original form within 35 s. Different weight fractions of MWNT/PVA composites were prepared by using a simple solution blending and transitional solution casting method, and their microstructures, electrical conductivities, thermal conductivities, and electroactive shape memory properties were investigated. According to our systematic analysis, the enhanced performance can be attributed to the reinforcement of MWNTs that led to the improved electrical and thermal conductivities of the PVA matrix.

Infectious diseases are a worldwide health concern. For some infections, a common feature is the intracellular residence of the pathogen and evasion of the host immune response. In the case of tuberculosis (TB), Mycobacterium tuberculosis evades clearance within macrophages through suppression of intracellular reactive oxygen and nitrogen species (ROS/RNS) and pro-inflammatory cytokines. We propose new nanoparticle designs for infectious diseases, functionalized with ligands able to modulate the cellular immune response and concurrently deliver drug. We have designed 1,3-β-glucan functionalized chitosan shell, poly(lactide)co-glycolide core nanoparticles to stimulate ROS/RNS, pro-inflammatory cytokine secretion, and delivery of rifampicin inside human alveolar like macrophages (ALM). Nanoparticles significantly enhanced ALM secretion of IL-12p70 (2.9-fold), TNF-α (16-fold) and INF-γ (23-fold) compared to controls over 24h, and doubled ROS/RNS generation over 6h. Nanoparticles could deliver 4-fold greater rifampicin into ALM compared to rifampicin solution. These results provide proof-of-concept of multimodal nanoparticles and support their further development. From the Clinical Editor In this paper, a new nanoparticle design is proposed to address hard to treat infectious diseases such as TB, through the use of nanoparticles functionalized with ligands that are able to concurrently modulate the cellular immune response and deliver a drug. The authors have designed 1,3-β-glucan functionalized chitosan shell - poly(lactide)co-glycolide core nanoparticles to stimulate reactive oxygen and nitrogen species production, pro-inflammatory cytokine secretion, and delivery of rifampicin inside human alveolar-like macrophages.

Nanoparticles (NPs) with high drug loading and pH-responsivity were prepared by nanoprecipitation of a hydrophobic polymer-drug conjugate (PDC). The PDC, polylactide-graft-doxorubicin (PLA-g-DOX), was synthesized by azide-alkyne click reaction to transform acetylene-functionalized PLA into PLA-graft-aldehyde (PLA-g-ALD), followed by DOX conjugation to form acid-sensitive Schiff base linkage between drug moieties and polymer scaffold. The DOX loading amount in PLA-g-DOX PDC was determined to be 32 wt % by (1)H NMR and UV-vis spectroscopies. PLA-g-DOX PDC was further used to prepare NPs with precisely controlled drug loading by nanoprecipitation in the presence of a PEGylated surfactant. The effects of organic solvent, PLA-g-DOX PDC concentration and PLA-g-DOX/surfactant mass ratio on size and size distribution of NPs were systematically examined based on analysis by dynamic light scattering (DLS) and transmission electron microscopy (TEM). NPs prepared under the optimal conditions exhibited well-defined spherical morphology with volume-average hydrodynamic diameter (Dh) around 100 nm. Due to the Schiff base conjugation linkage in PLA-g-DOX PDC, acid-sensitive drug release behavior of the NPs was observed. In vitro studies against MCF-7 breast cancer cells showed that the NPs can be readily taken up and result in enhanced therapeutic efficiency as compared to DOX·HCl, indicating their promising potential applications as anticancer nanomedicines.

We present a magnetoplasmonic nanoplatform combining gold nanorods (GNR) and iron-oxide nanoparticles within phospholipid-based polymeric nanomicelles (PGRFe). The gold nanorods exhibit plasmon resonance absorbance at near infrared wavelengths to enable photoacoustic imaging and photothermal therapy, while the Fe 3 O 4 nanoparticles enable magnetophoretic control of the nanoformulation. The fabricated nanoformulation can be directed and concentrated by an external magnetic field, which provides enhancement of a photoacoustic signal. Application of an external field also leads to enhanced uptake of the magnetoplasmonic formulation by cancer cells in vitro. Under laser irradiation at the wavelength of the GNR absorption peak, the PGRFe formulation efficiently generates plasmonic nanobubbles within cancer cells, as visualized by confocal microscopy, causing cell destruction. The combined magnetic and plasmonic functionalities of the nanoplatform enable magnetic field-directed, imaging-guided, enhanced photo-induced cancer therapy. From the Clinical Editor In this study, a nano-formulation of gold nanorods and iron oxide nanoparticles is presented using a phospholipid micelle-based delivery system for magnetic field-directed and imaging-guided photo-induced cancer therapy. The gold nanorods enable photoacoustic imaging and photothermal therapy, while the Fe 3 O 4 nanoparticles enable magnetophoretic control of the formulation. This and similar systems could enable more precise and efficient cancer therapy, hopefully in the near future, after additional testing.

To achieve a conjugated drug delivery system with high drug loading but minimal long-term side effects, a degradable brush polymer-drug conjugate (BPDC) was synthesized through azide-alkyne click reaction of acetylene-functionalized polylactide (PLA) with azide-functionalized paclitaxel (PTXL) and poly(ethylene glycol) (PEG). Well-controlled structures of the resulting BPDC and its precursors were verified by (1)H NMR and gel permeation chromatography (GPC) characterizations. With nearly quantitative click efficiency, drug loading amount of the BPDC reached 23.2 wt %. Both dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM) imaging indicated that the BPDC had a nanoscopic size around 10-30 nm. The significant hydrolytic degradability of the PLA backbone of the BPDC was confirmed by GPC analysis of its incubated solution. Drug release study showed that PTXL moieties can be released through the cleavage of the hydrolyzable conjugation linkage in pH 7.4 at 37 °C, with 50% release in about 22 h. As illustrated by cytotoxicity study, while the polymeric scaffold of the BPDC is nontoxic, the BPDC exhibited higher therapeutic efficacy toward MCF-7 cancer cells than free PTXL at 0.1 and 1 μg/mL. Using Nile red as encapsulated fluorescence probe, cell uptake study showed effective internalization of the BPDC into the cells.

In this paper, a new method for synthesizing non-aqueous copper sulfide nanocrystals with different shapes and sizes using a homemade continuous-flow millifluidic chip is presented. Conventionally, the shape control of nanocrystals was accomplished using a surfactant-controlled approach, where directional growth is facilitated by selective passivation of a particular facet of the nanocrystals using surfactants. We demonstrate a "surfactant-free" approach where different sizes and shapes (i.e. spherical, triangular prism and rod) of plasmonic copper sulfide (Cu(2-x)S) nanocrystals can be fabricated by adjusting the flow rate and precursor concentrations. As continuous-flow synthesis enables uniform heating and easy variation of precursors' stoichiometries, it serves as an excellent incubation platform for nanoparticles due to its simplicity and high reproducibility. Transmission electron microscopy (TEM), fast Fourier transform (FFT) and X-ray diffraction (XRD) techniques were used to characterize the as-synthesized nanocrystals and revealed structures ranging from copper-deficient covellite (CuS), spionkopite (Cu1.39S), roxbyite (Cu1.75S), to copper-rich djurleite (Cu1.94S). The localized surface plasmon resonance (LSPR) peak of the nanocrystals can be tuned from 1115 to 1644 nm by simply varying the copper to sulfur molar ratio and flow rate. Furthermore, photothermal effects of Cu(2-x)S nanocrystals were also demonstrated to annihilate the RAW264.7 cells upon near infra-red laser irradiation.

Light-induced photoluminescence (PL) switching using azobenzene-doped liquid crystal (LC)-dispersed quantum dots (QDs) is demonstrated in a format of LC cell and LC-infiltrated tube. Before light irradiation, excitation photons undergo multiple scattering events before emission out of the LC cell, and PL intensity is high. Upon the light irradiation, the trans-to-cis photoisomerization of azobenzene makes the QD-dispersed LCs highly transparent, thus allowing most excitation photons to pass through LCs and decrease PL intensity. This demonstration may allow a new modulating technique for future development of light-switchable, QD-emission-based display or photonic devices.

We report the use of silver-indium-sulfide (AgInS 2 ) quantum dots (QDs) as heavy metal-free photosensitizer for QDs-sensitized solar cell. For fabricating the TiO 2 /AgInS 2 electrode, the QDs were attached to a mesoporous TiO 2 surface by using bifunctional linker molecules. The fabricated TiO 2 /AgInS 2 electrode exhibits light absorption in the visible region and serves as the photoanode. Upon bandgap excitation, injection of photoexcited electrons from AgInS 2 QDs into the TiO 2 matrix produces photocurrents accordingly. The proof-of-concept AgInS 2 QDs-sensitized solar cell exhibits a short-circuit current of 0.49 mA/cm2 and open-circuit voltage of 0.24 V, under one sun illumination.

Functional polylactide-g-paclitaxel–poly(ethylene glycol), a novel graft polymer–drug conjugate (GPDC) with paclitaxel (PTXL) as the divalent agent to bridge between the degradable polylactide (PLA)-based backbone and hydrophilic poly(ethylene glycol) (PEG) side chains, were prepared by the copper-catalyzed azide–alkyne cycloaddition reaction of acetylene-functionalized polylactide (PLA) with azide-functionalized PTXL–PEG conjugate. The acetylene-functionalized PLA was prepared by ring-opening copolymerization (ROCP) of acetylene-functionalized LA monomer with l-lactide (LA). The azide-functionalized PTXL–PEG conjugate was prepared by multistep organic synthesis. The well-controlled chemical structures of the GPDC and its precursors were verified by 1H NMR and GPC characterizations. DLS analysis indicated that GPDC molecules assembled in water to form nanoparticles with sizes of 8–40 nm. GPC analysis of buffer solutions (pH = 5.5 and 7.4) of the GPDC suggested the occurrence of multiple hydrolysis reactio...

We report the use of biocompatible gold nano- rods (GNRs) as multimodal (plasmonic and magnetic) probes for cancer cell labeling in vitro. These multifunc- tional and multimodal bioconjugates were prepared by replacing cetyltrimethylammonium bromide with a mixture of functionalized PEGylation molecules so that a variety of functionalities (e.g., magnetic resonance imaging agent gadolinium (Gd) and biorecognition molecule transferrin (Tf)) can be easily integrated using simple chemistry. It was shown that Gd incorporation did not interfere with the plasmonic properties of the GNRs and a strong T1 relaxivity was estimated (10.0 mM �1 s �1 ), which is more than twice that of the clinical MRI agent Gd-DTPA. The large observed T1 relaxivity was possibly due to the huge surface to volume ratio of GNR, which allowed huge amount of amine-terminated molecule to anchor on the surface, coupled with Gd (III) ions for the enhanced relaxation of water protons. Pancreatic cancer cell over- expressing the transferring receptor was served as the in vitro model, and the Tf-mediated uptake was demonstrated and confirmed by dark-field imaging and transmission electron microscopy. More importantly, cell viability (MTS) assay did not reveal any sign of toxicity in these treated cells, suggesting that PEGylated GNRs can serve as a biocompatible, multifunctional, and multimodal platform for variable bio-applications.

Luminescent silicon quantum dots (SiQDs) are gaining momentum in bioimaging applications, based on their unique combination of optical properties and biocompatibility. Here, we report the development of a multimodal probe that combines the optical properties of silicon quantum dots with the superparamagnetic properties of iron oxide nanoparticles to create biocompatible magnetofluorescent nanoprobes. Multiple nanoparticles of each type are coencapsulated within the hydrophobic core of biocompatible phospholipid-polyethyleneglycol (DSPE-PEG) micelles. The size distribution and composition of the magnetofluorescent nanoprobes were characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Enhanced cellular uptake of these probes in the presence of a magnetic field was demonstrated in vitro. Their luminescence stability in a prostate cancer tumor model microenvironment was demonstrated in vivo. This paves the way for multimodal silicon quantum-dot-based nanoplatforms for a variety of imaging and delivery applications.

We report here solution-phase synthesis of multifunctional nanoprobes for imaging live cancer cells. More specifically, quantum dots (QDs) and magnetite (Fe3O4) nanoparticles were coencapsulated wi...

Using the 3(rd) generation Grubbs' catalyst as the initiator, diblock brush polymer drug conjugates (BPDCs) were synthesized by sequential ring-opening metathesis polymerization (ROMP) of a hydrophilic poly(ethylene glycol) (PEG)-based norbornene (NB)-functionalized macromonomer and a hydrophobic paclitaxel (PTXL)-based NB-functionalized monomer. These amphiphilic diblock BPDCs had well-defined structures, with narrow molecular weight distributions (Mw/Mn = 1.10-1.16). They self-assembled into multi-molecular nanostructures in aqueous solutions. Although the PTXL moieties were connected to the backbone with cycloacetal-based conjugation linkages, the cleavage of these linkages from the assemblies of diblock BPDCs was relatively slow and exhibited limited acid-sensitivity, indicating a significant influence of the macromolecular structure and assembly of BPDCs on their drug release behaviour. The cytotoxicity study not only showed that the diblock BPDCs are therapeutically effective against cancer cells, but also revealed a correlation between cytotoxicity and grafting structures of BPDCs. In summary, the results obtained in this work provide new insight into the structure-dependent properties of brush polymer-based drug delivery systems.

In this work, a surfactant-free emulsion polymerization method was utilized to synthesize poly(styrene-ran-methyl acrylate) (PSMA) at a styrene/(methyl acrylate) mole ratio of 75/25 with the aim to compatibilize high impact polystyrene (HIPS)/poly(lactic acid) (PLA) interface. HIPS/PLA blends with different PSMA contents were prepared. Their phase morphologies, mechanical properties, and rheological and crystallization behaviors were investigated using scanning electron microscopy, tensile tests, rotational rheometry, and differential scanning calorimetry. The rheological results showed that the complex viscosity, storage moduli, and loss moduli of PLA/HIPS blends were enhanced with increasing PSMA content. A decrease in the degree of crystallinity of PLA in PLA/HIPS blends with the addition of PSMA was observed in the differential scanning calorimetry results. It was also revealed that the addition of a small amount of PSMA can effectively improve the compatibility and thus the interfacial adhesion of the PLA/HIPS blends, thereby reducing the size of the HIPS dispersion phase. When 1 wt % of PSMA was used, compared with the PLA/HIPS blends without PSMA, the tensile strength and notched Charpy impact strength of PLA/HIPS blends were improved by 95.3% and 104.8%, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45799.

Correction for ‘Millifluidic synthesis of cadmium sulfide nanoparticles and their application in bioimaging’ by Liying Hong, Tai-Lok Cheung et al., RSC Adv., 2017, 7, 36819–36832.

Well-defined chitosan nanocapsules (CSNCs) with tunable sizes were synthesized through the interfacial cross-linking of N-maleoyl-functionalized chitosan (MCS) in miniemulsions, and their application in the delivery of doxorubicin (Dox) was investigated. MCS was prepared by the amidation reaction of CS with maleic anhydride in water/DMSO at 65 °C for 20 h. Subsequently, thiol-ene cross-linking was conducted in oil-in-water miniemulsions at room temperature under UV irradiation for 1 h, using MCS as both a surfactant and precursor polymer, 1,4-butanediol bis(3-mercapto-propionate) as a cross-linker, and D-α-tocopheryl poly(ethylene glycol) 1000 succinate as a cosurfactant. With the increase in cosurfactant concentration in the reaction systems, the sizes of the resulting CSNCs decreased steadily. Dox-loaded CSNCs were readily prepared by in situ encapsulation of Dox during miniemulsion cross-linking. With acid-labile β-thiopropionate cross-linkages, the Dox-loaded CSNCs demonstrated a faster release rate under acidic conditions. Relative to free Dox, Dox-loaded CSNCs exhibited enhanced cytotoxicity toward MCF-7 breast cancer cells without any noticeable cytotoxicity from empty CSNCs. The effective delivery of Dox to MCF-7 breast cancer cells via Dox-loaded CSNCs was also observed.

Cadmium-based quantum dots (QDs) have been extensively used for biomedical applications for the last decade. They have also been researched for drug and gene delivery. For this reason, efforts have been placed on evaluating their toxicity at in vivo level. The most widely used quantum dots are CdSe QDs and thus it is important for one to investigate the potential toxicity in vivo. In this contribution, we systematically study the effect of phospholipid micelle-encapsulated CdSe/CdS/ZnS QDs on the long term in vivo toxicity in Kunming mice. The biodistribution, animal survival, animal weight, hematology, blood biochemistry, and organ histology and their respective fluorescent images were determined at an overdose (50 mg kg−1) of phospholipid micelle-encapsulated QDs over 112 days (16 weeks) period. The results show that the phospholipid micelle-encapsulated QDs formulation did not result in noticeable toxicity. Serum analysis has shown no changes in the treated mice when compared to mice treated with PBS buffer solution. Histological analysis of tissues from major organs indicated that there are no acute toxic effects of the QDs in vivo. Fluorescent images indicated that the majority of the QDs accumulated in the liver and spleen. Due to the widespread use of Cd-based QDs and the potential for clinical use, these results are necessary and confirm the minimal health risk to use QDs as optical contrast agents and therapeutic carriers.

Surface modification and functionalization of bioconjugated quantum dots (QDs) has drawn great attention for the past few years due to their wide applications in biomedical research. In this contribution, we demonstrate the use of PEGylated phospholipid micelles to encapsulate near infrared emitting ultra-small lead sulfide (PbS) QDs for in vitro and in vivo imaging. The cytotoxicity of the micelle-encapsulated QDs formulation was evaluated using MTS assay and histological analysis studies. We have found that upon encapsulating the QDs with phospholipid micelle, the toxicity of the PbS QDs is reduced, from which we envision that the PEGylated phospholipid micelle-encapsulated PbS QDs formulation can be used as theranostics probes for some selected applications in cell imaging and small animals study. Published Version

In this study, we have developed a novel carrier, micelle-type bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles (NPs), for the detection and treatment of pancreatic cancer. These NPs contained 4-arm-PEG as corona, and PLGA as core, the particle surface was conjugated with cyclo(arginine-glycine-aspartate) (cRGD) as ligand for in vivo tumor targeting. The hydrodynamic size of the NPs was determined to be 150-180 nm and the critical micellar concentration (CMC) was estimated to be 10.5 mg l( - 1). Our in vitro study shows that these NPs by themselves had negligible cytotoxicity to human pancreatic cancer (Panc-1) and human glioblastoma (U87) cell lines. Near infrared (NIR) microscopy and flow cytometry demonstrated that the cRGD conjugated PLGA-4-arm-PEG polymeric NPs were taken up more efficiently by U87MG glioma cells, over-expressing the α(v)β(3) integrin, when compared with the non-targeted NPs. Whole body imaging showed that the cRGD conjugated PLGA-4-arm-PEG branched polymeric NPs had the highest accumulation in the pancreatic tumor site of mice at 48 h post-injection. Physical, hematological, and pathological assays indicated low in vivo toxicity of this NP formulation. These studies on the ability of these bioconjugated PLGA-4-arm-PEG polymeric NPs suggest that the prepared polymeric NPs may serve as a promising platform for detection and targeted drug delivery for pancreatic cancer.

In this paper, we report the successful use of non-cadmium based quantum dots (QDs) as highly efficient and non-toxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulphide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in non-aqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjugation with pancreatic cancer specific monoclonal antibodies, such as anti-claudin 4 and anti-prostate stem cell antigen (anti-PSCA), to the functionalized InP/ZnS QDs, allowed specific in vitro targeting of pancreatic cancer cell lines (both immortalized and low passage ones). The receptor mediated delivery of the bioconjugates was further confirmed by the observation of poor in vitro targeting in non-pancreatic cancer based cell lines which are negative for the claudin-4-receptor. These observations suggest the immense potential of InP/ZnS QDs as non-cadmium based safe and efficient optical imaging nanoprobes in diagnostic imaging, particularly for early detection of cancer.