Core-shell Polymeric Nanoparticles Research Articles

In situ PET-RAFT polymerization to prepare guanidine-and-carbohydrate modified ZnO nanoparticles

ZnO–polymer core–shell nanoparticles were successfully prepared using a simple in situ open-to-air PET-RAFT method.

All-solid-state lithium-sulfur batteries enabled by single-ion conducting binary nanoparticle electrolytes.

We designed solid-state hybrid electrolytes with single-ion conducting properties by co-assembling binary core-shell polymer nanoparticles. By controlling the nanoparticle size and number, we created superlattices that optimized the Li+ concentration and transport. The electrolytes exhibited a remarkable ionic conductivity (10-4 S cm-1), lithium transference number (0.94), electrochemical stability (up to 6 V), and modulus (0.12 GPa) at 25 °C. The mechanical strength of these electrolytes depended minimally on temperature at 25-150 °C because of the robustness of the cores. When implemented in Li-S batteries with no liquids, they demonstrated an initial discharge capacity of 1090 mA h g-1 at 0.05C, a cycle life of over 200 cycles, and a rate capability with a discharge capacity of 627 mA h g-1 at 3C.

Controlling the Formation of Polyelectrolyte Complex Nanoparticles Using Programmable pH Reactions.

Enabling complexation of weak polyelectrolytes, in the presence of a programmable pH-modulation, offers a means to achieve temporal control over polyelectrolyte coassembly. Here, by mixing oppositely charged poly(allylamine hydrochloride) and poly(sodium methacrylate) in a (bi)sulfite buffer, nanoscopic complex coacervates are formed. Addition of formaldehyde initiates the formaldehyde-sulfite clock reaction, affecting the polyelectrolyte assembly in two ways. First, the abrupt pH increase from the reaction changes the charge density of the polyelectrolytes and thus the ratio of cationic and anionic species. Simultaneously, reactions between the polyamine and formaldehyde lead to chemical modifications on the polymer. Interestingly, core-shell polymeric nanoparticles are produced, which remain colloidally stable for months. Contrastingly, in the same system, in the absence of the clock reaction, aggregation and phase separation occur within minutes to days after mixing. Introducing an acid-producing reaction enables further temporal control over the coassembly, generating transient nanoparticles with nanoscopic dimensions and an adjustable lifetime of tens of minutes.

Core-shell Pluronic F127/chitosan based nanoparticles for effective delivery of methotrexate in the management of rheumatoid arthritis

This study was designed to improve oral bioavailability of the methotrexate (MTX) by sustaining its release profile and integration into core-shell polymeric nanoparticles. The self-micellization and ionotropic gelation technique was employed which resulted into spherical shaped nanoparticles (181-417 nm) with encapsulation efficiency of 80.14% to 85.54%. Furthermore, Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry analyses were carried out to investigate physicochemical and thermal stability of the produced engineered core shell nanoparticles of the methotrexate. . Entrapment of drug in polymeric core was confirmed by X-ray diffraction analysis. In-vitro sustained release behavior of nanoparticles was observed at pH 6.8 for 48 h while low drug release was observed at pH 1.2 due to pH-responsive nature of Pluronic F127. Acute toxicity study confirmed safety and biocompatible profile of nanoparticles. MTX loaded polymeric nanoparticles ameliorated the pharmacokinetic profile (8 folds greater half-life, 6.26 folds higher AUC0−t and 3.48 folds higher mean residence time). In vivo study conducted in rat model depicted the improved therapeutic efficacy and healing of arthritis through MTX loaded polymeric nanoparticles, preferentially attributable to high accretion of MTX in the inflamed site. In conclusion, MTX loaded polymeric nanoparticles is an attractive drug delivery strategy for an effective management and treatment of rheumatoid arthritis.

A simplified reinforcement and fracture mechanism analysis model of epoxy nanocomposites based on finite element simulation

Understanding the reinforcement and fracture mechanism of polymer matrix nanocomposites is crucial for the design of high-performance composite materials. By taking boron nitride@boronate polymer core-shell nanoparticles modified epoxy resin nanocomposites (EPNCs) as an example, a reinforcement and fracture mechanism analysis model of nanocomposites was established through the combination of experiments and simulations. Instead of the traditional programming method by using the external language, a new modeling method was introduced with the help of Digimat. The results indicated that the interface force between (within) EP matrix and nanoparticles, the shell thickness and nanoparticle content play important roles in the reinforcement and fracture of EPNCs. The bending strength increases with the raising of particle content, but decreases with the increasing of shell thickness. The simulated results were consistent with the experiments. The interface force evolves according to the order of interfaces within particles and their shell > matrix-shell > matrix interior. A proper interfacial force can make interfacial debonding and matrix failure occur at the same time, thus improving both the strength and toughness of nanocomposites. This model construction will provide theoretical guidance for nanocomposites design and the clarification of reinforcement mechanism. • Cross-examination of analytical, numerical and experimental results is conducted. • Appropriate interface, thin shell and particle content play important roles in composites reinforcement mechanism. • Finite element evaluation of core-shell nanoparticles reinforced epoxy resin composites wais established.

Experimental Research on Seepage Law and Migration Characteristics of Core-Shell Polymeric Nanoparticles Dispersion System in Porous Media.

The nanoparticles dispersion system has complex migration characteristics and percolation law in porous media due to the interaction between the nanoparticles and porous media. In this paper, lab experiments were carried out to characterize the morphology, particle size distributions, and apparent viscosities of SiO2/P(MBAAm-co-AM) polymeric nanoparticle solution, investigate its migration characteristics in porous media, and probe its capability of enhanced oil recovery (EOR) in the reservoirs. Quartz microtubule, sand pack, and etched glass micromodels were used as the porous media in the flow and flooding experiments. Gray image-processing technology was applied to achieve oil saturation at different flooding stages in the micromodel for calculating the EOR of the SiO2/P(MBAAm-co-AM) polymeric nanoparticle solution. The results show that The SiO2/P(MBAAm-co-AM) polymeric nanoparticles are spherical with diameters ranging from 260 to 300 nm, and the thicknesses of the polymeric layers are in the range of 30–50 nm. As the swelling time increases from 24 to 120 h, the medium sizes of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles increase from 584.45 to 1142.61 nm. The flow of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles has obvious nonlinear characteristics and a prominent scale effect at a low-pressure gradient, and there should be an optimal matching relationship between its injection mass concentration and the channel size. The flow tests in the sand packs demonstrate that the SiO2/P(MBAAm-co-AM) polymeric nanoparticles can form effective plugging in the main flow channels at different permeability areas and can break through at the throat to fulfill the step-by-step profile control. Moreover, the profile control of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles strengthens with an increase in their swelling time. The microscopic flooding experiment in the etched glass micromodel confirms that the SiO2/P(MBAAm-co-AM) polymeric nanoparticles can block dynamically and alternatively the channels of different sizes with the form of loose or dense networks to adjust the fluid flow diversion, improve the sweep efficiency, and recover more residual oil. The SiO2/P(MBAAm-co-AM) polymeric nanoparticles can achieve an enhanced oil recovery of 20.71% in the micromodel.

Mitochondria-targeted alginate/triphenylphosphonium-grafted-chitosan for treatment of hepatocellular carcinoma.

Mitochondrial targeting of anticancer drugs can effectively eradicate chemotherapy-refractory cells through different mechanisms. This work presents the rational designing of mitochondria-targeted core–shell polymeric nanoparticles (NPs) for efficient delivery of doxorubicin (DOX) to the hepatic carcinoma mitochondria. DOX was electrostatically nano-complexed with sodium alginate (SAL) then coated with mitotropic triphenylphosphonium-grafted chitosan (TPP+-g-CS) nanoshell. Polyvinyl alcohol (PVA) was co-solubilized into the TPP+-g-CS solution to enhance the stability of the developed NPs. The optimum NPs formula is composed of TPP+-g-CS (0.05% w/v) coating a DOX-SAL core complex (0.05% w/v), with 0.2% PVA relative to CS (w/w). The optimum NPs attained an entrapment efficiency of 63.33 ± 10.18%; exhibited a spherical shape with particle size of 70–110 nm and a positive surface charge which enhances mitochondrial uptake. FTIR and DSC studies results were indicative of an efficacious poly-complexation. In vitro biological experiments proved that the developed mitotropic NPs exhibited a significantly lower IC50, effectively induced apoptotic cell death and cell cycle arrest. Moreover, the in vivo studies demonstrated an enhanced antitumor bioactivity for the mitotropic NPs along with a reduced biological toxicity profile. In conclusion, this study proposes a promising nanocarrier system for the efficient targeting of DOX to the mitochondria of hepatic tumors.

Gelatin nanoparticles via template polymerization for drug delivery system to photoprocess application in cells

Photodynamic therapy (PDT) is a clinical treatment based on the activation of light-absorbing photosensitizers (PS) to generate reactive oxygen species, which are toxic to the targeted disease cells. Because most PS are hydrophobic with poor water solubility, it is necessary to encapsulate and solubilize PS in aqueous conditions to improve the photodynamic action for this compound. In this work, gelatin-poly(acrylic acid) nanoparticles (PAA/gelatin nanoparticles) via template polymerization for incorporation aluminum chloride phthalocyanine (ClAlPc) as a model drug for PDT application were developed. Biocompatible core-shell polymeric nanoparticles were fabricated via template polymerization using gelatin and acrylic acid as a reaction system. The nanoparticulate system was studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by classical MTT assay. The obtained nanoparticles had a spherical shape and DLS particle size were determined further and was found to be around 170 nm. The phthalocyanine-loaded-nanoparticles maintained their photophysical behaviour after encapsulation. It is found that ClAlPc can be released from the nanoparticles in a sustained manner with a small initial burst release. In vitro cytotoxicity revealed that ClAlPc-loaded nanoparticles had similar cytotoxicity to free ClAlPc with mouse melanoma cancer cell line (B16-F10). In vitro photoeffects assay indicated that the nanoparticle formulation was superior in anticancer effect to free ClAlPc on mouse melanoma cancer cell line B16-F10. The results indicate that ClAlPc encapsulated in gelatin-poly(acrylic acid) nanoparticles are a successful delivery system for improving photodynamic activity in the target tissue.

Novel chitosan and bacterial cellulose biocomposites tailored with polymeric nanoparticles for modern wound dressing development

Dressing biomaterials play a key role in wound management keeping a moisture medium and protecting against external factors. Natural and synthetic materials could be used as dressings where chitosan and bacterial cellulose is one of the most important solutions. These biopolymers have been used for wound dressing based on their non-toxic, biodegradable, and biocompatible features. In this study, biocomposites based on bacterial cellulose and chitosan membranes tailored with antimicrobial loaded poly(N-isopropylacrylamide)/polyvinyl alcohol nanoparticles were prepared. Core-shell polymeric nanoparticles, bacterial cellulose/chitosan membranes, and biocomposites were independently loaded with silver sulfadiazine, a well-known sulfonamide antibacterial agent used in the therapy of mild-to-moderate infections for sensitive organisms. The chemistry, structure, morphology, and size distribution were investigated by Fourier transformed infrared spectroscopy (FTIR-ATR), RAMAN spectroscopy, Scanning electron (SEM) and Transmission electron microscopy (TEM), and Dynamic light scattering (DLS). In vitro release behaviors of silver sulfadiazine from polymeric nanoparticles and biocomposites were investigated. The biological investigations revealed good biocompatibility of both the nanoparticles and the biocomposites in terms of human dermal fibroblasts viability and proliferation potential. Finally, the drug-loaded polymeric biomaterials showed promising characteristics, proving their high potential as an alternative support to develop a biocompatible and antibacterial wound dressing.

Programmable Membrane-Mediated Attachment of Synthetic Virus-like Nanoparticles on Artificial Protocells for Enhanced Immunogenicity

The programming of protocells to implement and control the functions of living cells through activated membrane receptor signaling remains a challenge for the development of protoliving technologies. Here, we report a synthetic protocell capable of inducing high levels of macrophage activation in vitro. An immunogenic protocell comprising hyaluronic acid (HA)-polymer membrane decorated with synthetic virus-like particles derived from the functionalization of core-shell polymer nanoparticles with a Toll-like receptor agonist (Pam3SK4) and cell/protocell membrane-binding lectin (WGA) is fabricated. While the non-decorated HA-based protocells and functionalized SVLPs alone initiate moderate levels of macrophage activation, co-presentation of WGA and Pam3SK4 on the protocell membrane results in hyperactivation of the phagocytes via a synergistic multi-receptor process. This work offers opportunities for developing chemically programmable soft microscale agents capable of eliciting cellular signal transduction and genetic outputs and provides a step toward implementing future therapeutic strategies based on cognate interactions at the cell-protocell interface.

Aggregation-free and high stability core-shell polymer nanoparticles with high fullerene loading capacity, variable fullerene type, and compatibility towards biological conditions.

Fullerenes have unique structural and electronic properties that make them attractive candidates for diagnostic, therapeutic, and theranostic applications. However, their poor water solubility remains a limiting factor in realizing their full biomedical potential. Here, we present an approach based on a combination of supramolecular and covalent chemistry to access well-defined fullerene-containing polymer nanoparticles with a core–shell structure. In this approach, solvophobic forces and aromatic interactions first come into play to afford a micellar structure with a poly(ethylene glycol) shell and a corannulene-based fullerene-rich core. Covalent stabilization of the supramolecular assembly then affords core-crosslinked polymer nanoparticles. The shell makes these nanoparticles biocompatible and allows them to be dried to a solid and redispersed in water without inducing interparticle aggregation. The core allows a high content of different fullerene types to be encapsulated. Finally, covalent stabilization endows nanostructures with stability against changing environmental conditions.

Designed Boron‐Rich Polymeric Nanoparticles Based on Nano‐ion Pairing for Boron Delivery

Boron-rich particles with the boron fraction ca.10-20 wt % of controllable shape and size that can be easily prepared via simple ion co-assembly are promising material for tumor treatment by boron neutron capture therapy. Electroneutral, dynamic core-shell polymeric nanoparticles were prepared by co-assembly of cationic PEO-block-PGEA diblock copolymer with sodium closo-dodecaborate, Na2 [B12 H12 ]. This is the first example of polymer nanoparticles based on [B12 H12 ]2- nano-ion pairing. The high [B12 H12 ]2- loading is proven by calorimetry at physiological salt concentration. As a result of rational design, rod-, worm- and sphere-like particles were produced and further tested using human glioblastoma and cervical carcinoma cell lines. Rod-like particles yielded the highest internalization capability in all tested cell lines.

Highly Adhesive and Sustainable UV/Heat Dual-Curable Adhesives Embedded with Reactive Core-Shell Polymer Nanoparticles for Super-Narrow Bezel Display.

To achieve the seamless characteristics of displays, liquid crystal (LC) devices need a super-narrow bezel design. This device architecture can be constructed using functional adhesives that possess excellent physical and chemical properties. In this study, mechanically robust ultraviolet (UV)/heat dual-curable adhesives with outstanding reliability and processability have been fabricated using reactive poly(methyl methacrylate) (PMMA)/polyethyleneimine (PEI) core-shell nanoparticles. Their curing characteristics, narrow drawing processability, adhesive strength, elongation at break, and the contact contamination of LCs have been investigated. Compared to conventional adhesive material, the proposed adhesive containing multifunctional PMMA/PEI nanoparticles afforded a high adhesion strength of 40.2 kgf cm−2 and a high elongation of 64.8% due to the formation of a firm crosslinked network with matrix resins comprising bisphenol A epoxy resin and bisphenol A glycerolate dimethacrylate. Moreover, the proposed adhesive showed an excellent narrow drawing width of 1.2 mm, which is a prerequisite for super-narrow bezel display. With regard to LC contamination, it was found that the level of contamination could be remarkably reduced to 61 µm by a high-temperature curing process. This study makes a significant contribution to the development of advanced display, because it provides robust and sustainable display adhesives based on nanomaterials, thereby enhancing the life and sustained operability of displays.

Polymeric Core-Shell Nanoparticles Prepared by Spontaneous Emulsification Solvent Evaporation and Functionalized by the Layer-by-Layer Method.

The aim of our study was to develop a novel method for the preparation of polymeric core-shell nanoparticles loaded with various actives for biomedical applications. Poly(caprolactone) (PCL), poly(lactic acid) (PLA) and poly(lactide-co-glycolide) (PLGA) nanoparticles were prepared using the spontaneous emulsification solvent evaporation (SESE) method. The model active substance, Coumarin-6, was encapsulated into formed polymeric nanoparticles, then they were modified/functionalized by multilayer shells’ formation. Three types of multilayered shells were formed: two types of polyelectrolyte shell composed of biocompatible and biodegradable polyelectrolytes poly-L-lysine hydrobromide (PLL), fluorescently-labeled poly-L-lysine (PLL-ROD), poly-L-glutamic acid sodium salt (PGA) and pegylated-PGA (PGA-g-PEG), and hybrid shell composed of PLL, PGA, and SPIONs (superparamagnetic iron oxide nanoparticles) were used. Multilayer shells were constructed by the saturation technique of the layer-by-layer (LbL) method. Properties of our polymeric core-shell nanoparticle were optimized for bioimaging, passive and magnetic targeting.

Synthesis and Investigation of Stimuli-Responsive Amphiphilic Latex Nanoparticles by Seeded Emulsion Polymerization

Stimuli-responsive amphiphilic core-shell polymer nanoparticles are an important category of smart materials which have been studied due to their advantages of changing of physical or chemical properties in response of stimuli. In this study, poly[2(dimethylamino)ethyl methacrylate] (PDMAEMA) as hydrophilic core with hydrophobic layer polystyrene (PS) as shell were synthesized by seeded emulsion polymerization to achieve dual-sensitive core-shell nanoparticle (CSNP). Temperature- and CO2- responsive CSNPs were investigated as two important smart behaviors. The CSNPs were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). In addition, two essential parameters including the polymerization conversion and stability of polymer latexes were investigated. Obtained results showed that hydrophilicity-hydrophobicity balance of the latex nanoparticles could be changed by variation of temperature and induction of CO2 gas flow, as a result of temperature- and CO2-responsivities of the PDMAEMA core. The particle size of CSNP was increased when the temperature rised above the lower critical solution temperature (LCST) of the PDMAEMA. It is due to the formation of hydrogen bonds between water molecules and tertiary amine group which lead to swell in PDMAEMA below LCST, and deswelling from water above LCST of the PDMAEMA. Furthermore, the size of the latex nanoparticles was increased from 696 nm to 853 nm after CO2-bubbling which led to increase hydrophilicity or water swelling of PDMAEMA in latex nanoparticles.

Correction to “Determining the Thickness and Completeness of the Shell of Polymer Core–Shell Nanoparticles by X-ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry, and Transmission Scanning Electron Microscopy”

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to “Determining the Thickness and Completeness of the Shell of Polymer Core–Shell Nanoparticles by X-ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry, and Transmission Scanning Electron Microscopy”Anja MüllerAnja MüllerMore by Anja Müllerhttp://orcid.org/0000-0003-2085-3687, Thomas HeinrichThomas HeinrichMore by Thomas Heinrich, Sven TougaardSven TougaardMore by Sven Tougaard, Wolfgang S. M. WernerWolfgang S. M. WernerMore by Wolfgang S. M. Wernerhttp://orcid.org/0000-0002-4870-9137, Martin HronekMartin HronekMore by Martin Hronek, Valentin KunzValentin KunzMore by Valentin Kunz, Jörg RadnikJörg RadnikMore by Jörg Radnikhttp://orcid.org/0000-0003-0302-6815, Jörg M. StockmannJörg M. StockmannMore by Jörg M. Stockmann, Vasile-Dan HodoroabaVasile-Dan HodoroabaMore by Vasile-Dan Hodoroaba, Sigrid BenemannSigrid BenemannMore by Sigrid Benemann, Nithiya Nirmalananthan-BudauNithiya Nirmalananthan-BudauMore by Nithiya Nirmalananthan-Budau, Daniel GeißlerDaniel GeißlerMore by Daniel Geißlerhttp://orcid.org/0000-0001-7550-8448, Katia SparnacciKatia SparnacciMore by Katia Sparnacci, and Wolfgang E. S. Unger*Wolfgang E. S. UngerMore by Wolfgang E. S. UngerCite this: J. Phys. Chem. C 2020, 124, 6, 3923Publication Date (Web):January 30, 2020Publication History Published online30 January 2020Published inissue 13 February 2020https://doi.org/10.1021/acs.jpcc.0c00027Copyright © 2020 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoicewith CC-BY-NC-NDlicenseArticle Views501Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (505 KB) Get e-Alerts Get e-Alerts

Core\u2013shell polymeric nanoparticles co-loaded with photosensitizer and organic dye for photodynamic therapy guided by fluorescence imaging in near and short-wave infrared spectral regions

BackgroundBiodistribution of photosensitizer (PS) in photodynamic therapy (PDT) can be assessed by fluorescence imaging that visualizes the accumulation of PS in malignant tissue prior to PDT. At the same time, excitation of the PS during an assessment of its biodistribution results in premature photobleaching and can cause toxicity to healthy tissues. Combination of PS with a separate fluorescent moiety, which can be excited apart from PS activation, provides a possibility for fluorescence imaging (FI) guided delivery of PS to cancer site, followed by PDT.ResultsIn this work, we report nanoformulations (NFs) of core–shell polymeric nanoparticles (NPs) co-loaded with PS [2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a, HPPH] and near infrared fluorescent organic dyes (NIRFDs) that can be excited in the first or second near-infrared windows of tissue optical transparency (NIR-I, ~ 700–950 nm and NIR-II, ~ 1000–1350 nm), where HPPH does not absorb and emit. After addition to nanoparticle suspensions, PS and NIRFDs are entrapped by the nanoparticle shell of co-polymer of N-isopropylacrylamide and acrylamide [poly(NIPAM-co-AA)], while do not bind with the polystyrene (polySt) core alone. Loading of the NIRFD and PS to the NPs shell precludes aggregation of these hydrophobic molecules in water, preventing fluorescence quenching and reduction of singlet oxygen generation. Moreover, shift of the absorption of NIRFD to longer wavelengths was found to strongly reduce an efficiency of the electronic excitation energy transfer between PS and NIRFD, increasing the efficacy of PDT with PS-NIRFD combination. As a result, use of the NFs of PS and NIR-II NIRFD enables fluorescence imaging guided PDT, as it was shown by confocal microscopy and PDT of the cancer cells in vitro. In vivo studies with subcutaneously tumored mice demonstrated a possibility to image biodistribution of tumor targeted NFs both using HPPH fluorescence with conventional imaging camera sensitive in visible and NIR-I ranges (~ 400–750 nm) and imaging camera for short-wave infrared (SWIR) region (~ 1000–1700 nm), which was recently shown to be beneficial for in vivo optical imaging.ConclusionsA combination of PS with fluorescence in visible and NIR-I spectral ranges and, NIR-II fluorescent dye allowed us to obtain PS nanoformulation promising for see-and-treat PDT guided with visible-NIR-SWIR fluorescence imaging.

Dual-emission hydrogel nanoparticles with linear and reversible luminescence-response to pH for intracellular fluorescent probes

A type of dual-emission probe with highly recognizable luminescence-response to pH has been designed. For the prepared core-shell polymeric hydrogel nanoparticles probe (Eu(DBM)3Phen doped polystyrene (PS)-co-poly(N-isopropylacrylamide)(PNIPAM)/FITC), the red emission of inner encapsulated europium complexes Eu(DBM)3Phen is remained in the hydrophobic PS core and used as a stable reference signal. Comparingly, the green emission of outer electrostatic bonded fluorescent isothiocyanate (FITC) moieties on the hydrophilic PNIPAM shell is adjusted and acted linear and reversible luminescence-response to pH between 5.8 and 7.4 with an exact resolution of 0.1 units. As a remarkable and smart pH probe, the hydrogel nanoparticles show low biological toxicity and prolonged resistance to ions and photobleaching. Also, the probes have successfully discriminated the fluorescent imaging for cytoplasmic matrix based on different pH with minimum biologic background fluorescence. These dual-emission pH-sensitive hydrogel nanoparticles suggest potential applications in clinical medicine, such as cell imaging and disease diagnosis.

Determining the Thickness and Completeness of the Shell of Polymer Core–Shell Nanoparticles by X-ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry, and Transmission Scanning Electron Microscopy

Core–shell nanoparticles (CSNPs) have become indispensable in various industrial applications. However, their real internal structure usually deviates from an ideal core–shell structure. To control how the particles perform with regard to their specific applications, characterization techniques are required that can distinguish an ideal from a nonideal morphology. In this work, we investigated poly(tetrafluoroethylene)–poly(methyl methacrylate) (PTFE–PMMA) and poly(tetrafluoroethylene)–polystyrene (PTFE–PS) polymer CSNPs with a constant core diameter (45 nm) but varying shell thicknesses (4–50 nm). As confirmed by transmission scanning electron microscopy (T-SEM), the shell completely covers the core for the PTFE–PMMA nanoparticles, while the encapsulation of the core by the shell material is incomplete for the PTFE–PS nanoparticles. X-ray photoelectron spectroscopy (XPS) was applied to determine the shell thickness of the nanoparticles. The software SESSA v2.0 was used to analyze the intensities of the e...

Shell Architecture Strongly Influences the Glass Transition, Surface Mobility, and Elasticity of Polymer Core-Shell Nanoparticles.

Despite the growing application of nanostructured polymeric materials, there still remains a large gap in our understanding of polymer mechanics and thermal stability under confinement and near polymer–polymer interfaces. In particular, the knowledge of polymer nanoparticle thermal stability and mechanics is of great importance for their application in drug delivery, phononics, and photonics. Here, we quantified the effects of a polymer shell layer on the modulus and glass-transition temperature (Tg) of polymer core–shell nanoparticles via Brillouin light spectroscopy and modulated differential scanning calorimetry, respectively. Nanoparticles consisting of a polystyrene (PS) core and shell layers of poly(n-butyl methacrylate) (PBMA) were characterized as model systems. We found that the high Tg of the PS core was largely unaffected by the presence of an outer polymer shell, whereas the lower Tg of the PBMA shell layer decreased with increasing PBMA thickness. The surface mobility was revealed at a temperature about 15 K lower than the Tg of the PBMA shell layer. Overall, the modulus of the core–shell nanoparticles decreased with increasing PBMA shell layer thickness. These results suggest that the nanoparticle modulus and Tg can be tuned independently through the control of nanoparticle composition and architecture.