Facile Functionalization of Gold Nanoparticles with PLGA Polymer Brushes and Efficient Encapsulation into PLGA Nanoparticles: Toward Spatially Precise Bioimaging of Polymeric Nanoparticles

Nanocarriers prepared from poly(lactide‐co‐glycolide) (PLGA) have broad biomedical applications. Understanding their cellular uptake and distribution requires appropriate visualization in complex biological compartments with high spatial resolution, which cannot be offered by traditional imaging techniques based on fluorescent or radioactive probes. Herein, the encapsulation of gold nanoparticles (GNPs) into PLGA nanoparticles is proposed, which should allow precise spatial visualization in cells using electron microscopy. Available protocols for encapsulating GNPs into polymeric matrices are limited and associated with colloidal instability and low encapsulation efficiency. In this report, the following are described: 1) a facile protocol to functionalize GNPs with PLGA polymer followed by 2) encapsulation of the prepared PLGA‐capped GNPs into PLGA nanocarriers with 100% encapsulation efficiency. The remarkable encapsulation of PLGA‐GNPs into PLGA matrix obeys the general rule in chemistry “like dissolves like” as evident from poor encapsulation of GNPs capped with other polymers. Moreover, it is shown that how the encapsulated gold nanoparticles serve as nanoprobes to visualize PLGA polymeric hosts inside cancer cells at the spatial resolution of the electron microscope. The described methods should be applicable to a wide range of inorganic nanoprobes and provide a new method of labeling pharmaceutical polymeric nanocarriers to understand their biological fate at high spatial resolution.     

Effects of poly(ethylene glycol) on electrical conductivity of poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonic acid) film

A series of poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonic acid) composite thin films with prescribed concentrations of poly(ethylene glycol) were prepared. The PEDOT–PSS pristine film and PEDOT–PSS/PEG films were studied using four-probe method, photoelectron spectroscopy and atomic force microscopy. The electrical conductivity of PEDOT–PSS/PEG hybrid films was found to be enhanced compared to the PEDOT–PSS pristine film, depending on the PEG concentration and molecular weight. XPS analysis and AFM results showed that PEG induces the phase separation between the PEDOT–PSS conducting particles and the excessive PSSNa shell. Simultaneously PEG may form hydrogen bond with sulfonic groups of PSSH, and hence weaken the electrostatic interactions between PEDOT cationic chains and PSS anionic chains. These resulted in the creation of a better conduction pathway among PEDOT–PSS particles, attributed to the improvement of conductivity.     

Systemic Administration of Polymer‐Coated Nano‐Graphene to Deliver Drugs to Glioblastoma

Graphene—2D carbon—has received significant attention thanks to its electronic, thermal, and mechanical properties. Recently, nano‐graphene (nGr) has been investigated as a possible platform for biomedical applications. Here, a polymer‐coated nGr to deliver drugs to glioblastoma after systemic administration is reported. A biodegradable, biocompatible poly(lactide) (PLA) coating enables encapsulation and controlled release of the hydrophobic anticancer drug paclitaxel (PTX), and a hydrophilic poly(ethylene glycol) (PEG) shell increases the solubility of the nGr drug delivery system. Importantly, the polymer coating mediates the interaction of nGr with U‐138 glioblastoma cells and decreases cytotoxicity compared with pristine untreated nGr. PLA‐PEG‐coated nGr is also able to encapsulate PTX at 4.15 wt% and sustains prolonged PTX release for at least 19 d. PTX‐loaded nGr‐PLA‐PEGs are shown to kill up to 20% of U‐138 glioblastoma cells in vitro. Furthermore, nGr‐PLA‐PEG and CNT‐PLA‐PEG, two carbon nanomaterials with different shapes, are able to kill U‐138 in vitro as well as free PTX at significantly lower doses of drug. Finally, in vivo biodistribution of nGr‐PLA‐PEG shows accumulation of nGr in intracranial U‐138 glioblastoma xenografts and organs of the reticuloendothelial system.     

Anti‐CRLF2 Antibody‐Armored Biodegradable Nanoparticles for Childhood B‐ALL

B‐precursor acute lymphoblastic leukemia (B‐ALL) lymphoblast (blast) internalization of anti‐cytokine receptor‐like factor 2 (CRLF2) antibody‐armored biodegradable nanoparticles (AbBNPs) are investigated. First, AbBNPsaere synthesized by adsorbing anti‐CRLF2 antibodies to poly(D,L‐lactide‐co‐glycolide) (PLGA) nanoparticles of various sizes and antibody surface density (Ab/BNP) ratios. Second, AbBNPs are incubated with CRLF2‐overexpressing (CRLF2+) or control blasts. Third, internalization of AbBNPs by blasts is evaluated by multicolor flow cytometry as a function of receptor expression, AbBNP size, and Ab/BNP ratio. Results from these experiments are confirmed by electron microscopy, fluorescence microscopy, and Western blotting. The optimal size and Ab/BNP for internalization of AbBNPs by CRLF2+ blasts is 50 nm with 10 Ab/BNP and 100 nm with 25 Ab/BNP. These studies show that internalization of AbBNPs in childhood B‐ALL blasts is AbBNP size‐ and Ab/BNP ratio‐dependent. All AbBNP combinations are non‐cytotoxic. It is also shown that CD47 is very slightly up‐regulated by blasts exposed to AbBNPs. CD47 is “the marker of self” overexpressed by blasts to escape phagocytosis, or “cellular devouring”, by beneficial macrophages. The results indicate that precise engineering of AbBNPs by size and Ab/BNP ratio may improve the internalization and selectivity of future biodegradable nanoparticles for the treatment of leukemia patients, including drug‐resistant minority children and Down's syndrome patients with CRLF2+B‐ALL.     

Fabrication of Magnetically Stirrable Anisotropic Microparticles via the Microfluidic Method

A one‐step strategy to fabricate magnetically stirrable microparticles with geometric/chemical anisotropies via a microfluidic technique combined with partial phase separation is presented. Monodisperse oil‐in‐water microemulsions composed of magnetite nanoparticles (MNPs) and two polymers, polystyrene and poly(d ,l ‐lactide‐co‐glycolide) (PLGA), dissolved in chloroform are generated using the microfluidic method. Upon incubating the microemulsions in pure water at ambient conditions, the solvent contained in the microemulsions is gradually removed and partial phase separation between the two polymers occurs spontaneously. In the meantime, the microemulsion droplets are vertically aligned due to the density difference of the two polymer phases. During the spontaneous phase separation, the MNPs become unstable and the aggregated MNPs segregate downward by gravity to the denser PLGA phase. After complete removal of the solvent, the resulting particles adopt geometric/chemical anisotropies, and they are magnetically rotatable under an external magnetic field. It is demonstrated that the morphology of the anisotropic particles can be controlled readily by adjusting the ratio of the two polymers as well as the concentration of MNPs. It is believed that the developed method based on the partial phase separation and the gravity‐induced segregation of the MNPs enables large‐scale production of magnetically stirrable microparticles.     

Characteristics of Rubber/Sodium Montmorillonite Nanocomposites Prepared by a Novel Method

In order to enhance the fine dispersion of hydrophilic sodium montmorillonite (Na‐MMT) in the matrix of hydrophobic rubber, the hydrophobic modification of Na‐MMT was carried out via an in situ method in the melt compounding process using the modifiers poly(ethylene glycol) monooleate or poly(ethylene glycol) diacrylate, both of which have a hydrophilic poly(ethylene glycol) (PEG) segment and a hydrophobic hydrocarbon segment. The X‐ray diffraction patterns showed that the interlayer distance of Na‐MMT was expanded by the intercalation of these modifiers. The morphology observed by scanning electron microscopy as well as the cure characteristics and tensile modulus showed that this organic modification effectively enhanced the fine dispersion of Na‐MMT in the rubber matrix.     

Multifunctional Polymer‐Coated Carbon Nanotubes for Safe Drug Delivery

Although progress in the use carbon nanotubes in medicine has been most encouraging for therapeutic and diagnostic applications, any translational success must involve overcoming the toxicological and surface functionalization challenges inherent in the use of such nanotubes. Ideally, a carbon‐nanotube‐based drug delivery system would exhibit low toxicity, sustained drug release, and persist in circulation without aggregation. Here, carbon nanotubes (CNTs) coated with a biocompatible block‐co‐polymer composed of poly(lactide)‐poly(ethylene glycol) (PLA‐PEG) are reported to reduce short‐term and long‐term toxicity, sustain drug release of paclitaxel (PTX), and prevent aggregation. The copolymer coating on the surface of CNTs significantly reduces in vitro toxicity. Moreover, the coating reduces the in vitro inflammatory response. Compared to non‐coated CNTs, in vivo studies show no long‐term inflammatory response with CNT coated with PLA‐PEG (CLP) and the surface coating significantly decreases acute toxicity by doubling the maximum tolerated dose in mice. In vivo biodistribution and histology studies suggest a lower degree of aggregation in tissues.     

Clustering of Iron Oxide Nanoparticles with Amphiphilic Invertible Polymer Enhances Uptake and Release of Drugs and MRI Properties

A functionalization of iron oxide nanoparticles (NPs) of different diameters by the amphiphilic invertible polymer, (PEG600‐alt‐PTHF650)_k (PEG and PTHF stand for poly(ethylene glycol) and poly(tetrahydrofuran), respectively), leads to different NP/polymer architectures for dye/drug uptake and release, as is reported here for the first time. It is demonstrated that 18.6 ± 1.4 and 11.9 ± 0.6 nm NPs are individually coated by this polymer, while 5.9 ± 0.6 nm NPs form nanoparticle clusters (NPCs) which could be isolated by either ultracentrifugation or magnetic separation. This phenomenon is most likely due to the character of the (PEG600‐alt‐PTHF650)_k macromolecule with alternating hydrophilic and hydrophobic fragments and its dimensions sufficient to cause NP clustering. Utilizing Rhodamine B base (RBB) and doxorubicin (DOX), the data on uptake upon mixing and further release via inversion into octanol (mimicking the penetration of the cell biomembrane) are presented. The magnetic NPCs display enhanced uptake and release of both RBB and DOX most likely due to the higher retained polymer amount. The NPCs also display exceptional magnetic resonance imaging properties. This and the high uptake/release efficiency of the NPCs combined with easy magnetic separation make them promising for theranostic probes for magnetically targeted drug delivery.     

Taxanes Hybrid Nanovectors: From Design to Physico‐Chemical Evaluation of Docetaxel and Paclitaxel Gold (III)‐PEGylated Complex Nanocarriers

This study gives an original methodology to synthetize novel metallo‐drugs nanoparticles relevant for medicinal chemistry. Gold (HAuCl₄) are complexes with antitumor compounds (paclitaxel (PTX); docetaxel (DTX)) and dicarboxylic acid‐terminated polyethylene‐glycol (PEG) that plays a role of surfactants. The proposed synthesis is fast and leads to hybrid‐metal nanoparticles (AuNPs) in which drug solubility is improved. The interactions between drugs (DTX, PTX), PEG diacid (PEG), and Au (III) ions to form hybrid nanocarriers called DTX IN PEG‐AuNPs and PTX IN PEG‐AuNPs, are characterized by various analytical techniques (Raman and UV–vis spectroscopies) and transmission electron microscopy. The efficient drugs release under pH conditions is also achieved and characterized showing an amazing reversible equilibrium between Au (III)‐complex‐drug and Au⁰NPs. For therapeutic purposes, such AuNPs are then decorated with the anti‐EGFR polyclonal antibodies, which specifically recognizes the hERG1 channel aberrantly expressed on the membrane of human lung cancer cells. This paper, through an original chemical approach, will occupy an important position in the field of nanomedicine, and hope that novel perspectives will be proposed for the development of high drug‐loading nanomedicines.     

Gold‐Nanoparticle‐Assisted Self‐Assembly of Chemical Gradients with Tunable Sub‐50 nm Molecular Domains

A simple and efficient principle for nanopatterning with wide applicability in the sub‐50 nanometer regime is chemisorption of nanoparticles; at homogeneous substrates, particles carrying surface charge may spontaneously self‐organize due to the electrostatic repulsion between adjacent particles. Guided by this principle, a method is presented to design, self‐assemble, and chemically functionalize gradient nanopatterns where the size of molecular domains can be tuned to match the level corresponding to single protein binding events. To modulate the binding of negatively charged gold nanoparticles both locally (<100 nm) and globally (>100 μm) onto a single modified gold substrate, ion diffusion is used to achieve spatial control of the particles’ mutual electrostatic interactions. By subsequent tailoring of different molecules to surface‐immobilized particles and the void areas surrounding them, nanopatterns are obtained with variable chemical domains along the gradient surface. Fimbriated Escherichia coli bacteria are bound to gradient nanopatterns with similar molecular composition and macroscopic contact angle, but different sizes of nanoscopic presentation of adhesive (hydrophobic) and repellent poly(ethylene) glycol (PEG) domains. It is shown that small hydrophobic domains, similar in size to the diameter of the bacterial fimbriae, supported firmly attached bacteria resembling catch‐bond binding, whereas a high number of loosely adhered bacteria are observed on larger hydrophobic domains.     

Microphase separation behavior on the surfaces of PEG-MDI-PDMS multiblock copolymer coatings

A series of poly(ethylene glycol)(PEG)-4,4′-diphenylmethanediisocyanate(MDI)-poly(dimethylsiloxane) (PDMS) multiblock copolymers were synthesized by employing two-step growth polymerization technique. Atomic force microscopy (AFM) observed nanoscopically well-organized phase-separated surfaces consisting of hydrophilic domain from PEG and MDI segments and hydrophobic domain from PDMS segments even with 50 wt.% PDMS in the copolymer, and the multiblock copolymer coatings presented a surface free energy of as low as 6-8 mN m⁻¹.     

Antibacterial Activity of Ciprofloxacin-Loaded Poly(lactic-co-glycolic acid)-Nanoparticles Against Staphylococcus aureus

The formation of bacterial biofilms on material surfaces is a recurrent problem in public health. Antibacterial nanoparticles (NPs) are promising because pathogens have not yet developed resistance mechanisms and encapsulation of the drug can protect it from the surrounding medium and improve pharmacokinetics. Biocompatible and biodegradable particles of various sizes (nano- and micro-scale) based on poly(lactic-co-glycolic acid) (PLGA) are elaborated using a simple and free toxic nanoprecipitation process. Particles are poly(ethylene glycol) (PEG)-ylated in order to reduce unwanted interactions with biological fluids, or loaded with the large spectrum antibiotic ciprofloxacin (CIP). NPs are studied against Staphylococcus aureus in planktonic and biofilm modes. Empty NPs with smallest size (60 nm) are able to totally eradicate planktonic culture after 24 h, even in the presence of serum proteins. CIP-loaded NPs present slightly lower antimicrobial activity against planktonic microorganisms compared with the free antibiotic, due to progressive release of CIP over time. In biofilm mode, CIP-loaded NPs show a very good antibiofilm activity, much better than free CIP, thanks to NPs penetration within the polymer matrix and a consequent release of the antibiotic close to the embedded bacteria. The present results open the way for widespread applications of PLGA-NPs in the pharmaceutical or medical fields.     

Structure and Stability of PEG‐ and Mixed PEG‐Layer‐Coated Nanoparticles at High Particle Concentrations Studied In Situ by Small‐Angle X‐Ray Scattering

Ligand‐layer structure and stability of gold nanoparticles (AuNP) coated with α‐methoxypoly(ethylene glycol)‐ω‐(11‐mercaptoundecanoate) (PEGMUA) layers and mixed layers of PEGMUA and 11‐mercaptoundecanoic acid (MUA) at high AuNP concentrations are studied in situ by small‐angle X‐ray scattering (SAXS). The thickness of the ligand layer is modified by the molecular weight of the PEG‐ligands (2 and 5 kDa), and the PEG‐grafting density is decreased by coadsorption of MUA. The response of the conjugates to a pressure of up to 4 kbar is probed. The results indicate strongly hydrated PEG layers at high grafting densities. The stability of the mixed ligand‐layer conjugates is lower. This is most probably due to enhanced interparticle PEG–PEG interactions at lower grafting densities. The presented study demonstrates that a detailed structural characterization of polymer ligand layers in situ and in response to external stimuli is possible with SAXS.     

BaSO4 nanorods produced in polymer-modified bicontinuous microemulsions

The influence of the water soluble polymer poly(ethylene glycol) (PEG) on structure formation in the quasiternary system sodium dodecylsulfate (SDS)/pentanol-xylene/water was checked by means of conductometry, rheology, and micro differential calorimetry. The polymer induces the formation of an isotropic phase channel between the o/w and w/o microemulsion. The transition from the normal as well as from the inverse micellar to the bicontinuous phase range can be detected by conductometry, rheology as well as micro-DSC. As a result of polymer–surfactant interactions, the spontaneous curvature of the surfactant film is changed and a sponge phase is formed. The bicontinuous phase is characterized by a moderate shear viscosity, a Newtonian flow behaviour, and the disappearence of interphasal water in the heating curve of the micro-DSC. When the polymer-modified bicontinuous phase is used as a template phase for the nanoparticle formation, spherical BaSO₄ nanoparticles were formed. During the following solvent evaporation process the primarily formed spherical nanoparticles aggregate to nanorods and triangular structures due to the non-restriction of the bicontinuous template phase in longitudinal direction.     

Polymeric Micelles Employing Platinum(II) Linker for the Delivery of the Kinase Inhibitor Dactolisib

Polymeric micelles are attractive nanocarriers for hydrophobic drug molecules such as the kinase inhibitor dactolisib. Two different poly(ethylene glycol)–poly(acrylic acid) (PEG‐b‐PAA) block‐copolymers are synthesized, PEG(5400)‐b‐PAA(2000) and PEG(10000)‐b‐PAA(3700), respectively. Polymeric micelles are formed by self‐assembly once dactolisib is conjugated via the ethylenediamine platinum(II) linker (Lx) to the PAA block of the block copolymers. Dactolisib micelles with dactolisib loading content of 17% w/w show good colloidal stability and display sustained release of Lx‐dactolisib over 96 h in PBS at 37 °C, while media containing reagents that compete for platinum coordination (e.g., glutathione (GSH) or dithiothreitol (DTT)) effectuate release of the parent inhibitor dactolisib at similar release rates. Dactolisib/lissamine‐loaded micelles are internalized by human breast adenocarcinoma cells (MCF‐7) in a dose and time‐dependent manner as demonstrated by confocal microscopy. Dactolisib‐loaded micelles inhibit the PI3K/mTOR signaling pathway at low concentrations (400 × 10^?9 m ) and exhibit potent cytotoxicity against MCF‐7 cells with IC₅₀ values of 462 ± 46 and 755 ± 75 × 10^?9 m for micelles with either short or longer PEG‐b‐PAA block lengths. In conclusion, dactolisib loaded PEG‐b‐PAA micelles are successfully prepared and hold potential for nanomedicine‐based tumor delivery of dactolisib.     

Synergistic effect of silver seeds and organic modifiers on the morphology evolution mechanism of silver nanoparticles

Triangular, truncated triangular, quadrangular, hexagonal, and net-structured silver nanoplates as well as decahedral silver nanoparticles were manipulatively prepared starting from silver nitrate and silver seeds in the presence of poly(ethylene glycol) (PEG), poly(N-vinyl pyrrolidone) (PVP), and Tween 80 at room temperature, respectively. UV-vis spectroscopy, XRD, HRTEM, SAED, and FTIR were used to illustrate the crystal growth process and to characterize the resultant silver nanoparticles. It was found that the silver seeds and organic modifiers synergistically affected the morphology evolution of the silver nanoparticles. The co-presence of silver seeds and PEG was beneficial to the formation of triangular and truncated triangular silver nanoplates; the silver seeds and PVP favored the formation of polygonal silver nanoplates; the silver seeds and Tween 80 preferred to the formation of net-structured silver plates. The morphology evolution of the resultant silver nanoparticles was correlated with the crystallinity of the silver seeds and the adsorption ability of the organic modifiers on the crystal surfaces.     

Preparation and In-vitro Degradation Behavior of Poly(L-lactide-co-glycolide-co-ε-caprolactone) Terpolymer

A random terpolymer of poly(L-lactide-co-glycolide-co-ε-caprolactone) (PLLGC) was synthesized from L-lactide, glycolide and ε-caprolactone. The in-vitro hydrolytic degradation behavior of the PLLGC terpolymer was investigated as a function of the degradation time; the results showed that the degradation rate of PLLGC was lower than that of PLGA due to a reduction in the acidic degradation products. Therefore, we suggest the degradation rate of the PLGA could be controllable by introduction of ε-caprolactone into the PLGA martrix, while the physical properties (mechanical, etc.) were superior to PLGA.     

A Comparative Study of Chemical Routes for Coating Gold Nanoparticles via Controlled RAFT Emulsion Polymerization

The synthesis of core‐shell Au nanoparticles protected by an amphiphilic block copolymer is investigated by distinct reversible addition fragmentation chain transfer (RAFT) emulsion polymerization routes. The controlled polymerization of polymer shells onto Au nanoparticles is attempted by using the macroRAFT (MR) agent based on 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid synthesized via RAFT polymerization of poly(ethylene glycol) methyl ether acrylate and exploring several approaches, which include (i) post‐modification; (ii) in situ synthesis and (iii) “grafting from” strategies. In the conditions investigated here all these strategies lead to Au polymer nanocomposites but morphological well‐defined core‐shell nanoparticles are only obtained by applying the “grafting from” strategy. In particular, conditions that promote chain extension from the MR agent adsorbed onto the Au nanoparticles are found necessary to obtain nanostructures with such morphological characteristics and that still show the localized surface plasmon resonance typical of colloidal Au nanoparticles.     

Docetaxel‐Loaded Nanoparticles of Dendritic Amphiphilic Block Copolymer H40‐PLA‐b‐TPGS for Cancer Treatment

A dendritic amphiphilic block copolymer H40‐poly(d,l ‐lactide)‐block‐d‐α‐tocopheryl polyethylene glycol 1000 succinate (H40‐PLA‐b‐TPGS) is synthesized, which is then employed to develop a system of nanoparticles (NPs) loaded with docetaxel (DTX) as a model drug for cancer treatment due to its higher drug‐loading content and drug encapsulation efficiency, smaller particle size, faster drug release, and higher cellular uptake in comparison to the linear PLA polymer NPs and PLA‐b‐TPGS copolymer NPs. The drug‐loaded NPs are prepared by a modified nanoprecipitation method and characterized in terms of size and size distribution, surface morphology, drug release profile, and physical state of DTX. Cellular uptake of coumarin 6‐loaded NPs by MCF‐7 cancer cells is determined by flow cytometry and confocal laser scanning microscopy. The antitumor efficacy of the drug‐loaded NPs is investigated in vitro by MTT assay and in vivo by xenograft tumor model. The 72 h IC50 of the drug formulated in the PLA, PLA‐b‐TPGS, and H40‐PLA‐b‐TPGS NPs is found to be, 1.5 ± 0.3, 0.9 ± 0.1, and 0.15 ± 0.06 μg mL^?1, which are 7.3, 12.2, and 73.3‐fold effective than 11.0 ± 1.2 μg mL^?1 for Taxotere, respectively. Such advantages are further confirmed by the measurement of the tumor size and weight.