RAFT made methacrylate copolymers for reversible pH-responsive nanoparticles

All-Aqueous, Surfactant-Free, and pH-Driven Nanoformulation Methods of Dual-Responsive Polymer Nanoparticles and their Potential use as Nanocarriers of pH-Sensitive Drugs

All-aqueous, surfactant-free, and pH-driven nanoformulation methods to generate pH- and temperature-responsive polymer nanoparticles (NPs) are described. Copolymers comprising a poly(methyl methacrylate) (PMMA) backbone with a few units of 2-(dimethylamino)ethyl methacrylate (DMAEMA) are solubilized in acidic buffer (pH 2.0) to produce pH-sensitive NPs. Copolymers of different molar mass (2.3-11.5 kg mol^-1 ) and DMAEMA composition (7.3-14.2 mol%) are evaluated using a "conventional" pH-driven nanoformulation method (i.e., adding an aqueous polymer solution (acidic buffer) into an aqueous non-solvent (basic buffer)) and a robotized method for pH adjustment of polymer dispersions. Dynamic light scattering, zeta-potential (ζ), and sedimentation-diffusion analyses suggest the formation of dual-responsive NPs of tunable size (from 20 to 110 nm) being stable for at least 28 days in the pH and temperature intervals from 2.0 to 6.0 and 25 to 50 °C, respectively. Ultraviolet-visible spectroscopic experiments show that these NPs can act as nanocarriers for the pH-sensitive dipyridamole drug, expanding its bioavailability and potential controlled release as a function of pH and temperature. These approaches offer alternative strategies to prepare stimuli-responsive NPs, avoiding the use of harmful solvents and complex purification steps, and improving the availability of biocompatible polymer nanoformulations for specific controlled release of pH-sensitive cargos.

pH-responsive nonwoven fabric with reversibly wettability for controllable oil-water separation and heavy metal removal

Removal of organic solvents and heavy metals in effluents is of great significance to environmental pollution control and ecological civilization construction. pH-responsive materials have unique advantages in treating complicated oily wastewater. In this work, an intelligent pH-responsive nonwoven fabric with excellent reversible wettability was prepared. The pH-sensitive polymer was synthesized by free radical polymerization (FRP) technique, then dipped with SiO₂ on PP fabric. The particular molecular structure of poly (dimethylaminoethyl methacrylate) (PDMAEMA) enabled the fabric surface to switch wettability rapidly between hydrophilic/underwater oleophobic and oleophobic/hydrophobic under pH stimulus and exhibit controllable selective separation of various oil/water mixtures. Furthermore, the fabric removed Pb²⁺ efficiently under a wide pH range. The experimetal results showed that the separation flux reached 19,229 ± 1656.43 L-h^-1-m^-2 for water and 19,342 ± 1796.77 L-m^-2-h^-1 for n-hexane. Besides, the obtained fabric effectively realized the separation and collection process of complex ternary mixtures. The fabric removed Pb²⁺ in solutions with efficiency up to 90.83%. After immersing in acid and alkali solutions for 24 h, no significant damage to the surface wettability. This economical and intelligent fabric is able to meet the different separation purposes of industrial wastewaters with complex compositions.

Prediction of Nanoparticle Sizes for Arbitrary Methacrylates Using Artificial Neuronal Networks

Particle sizes represent one of the key factors influencing the usability and specific targeting of nanoparticles in medical applications such as vectors for drug or gene therapy. A multi-layered graph convolutional network combined with a fully connected neuronal network is presented for the prediction of the size of nanoparticles based only on the polymer structure, the degree of polymerization, and the formulation parameters. The model is capable of predicting particle sizes obtained by nanoprecipitation of different poly(methacrylates). This includes polymers the network has not been trained with, indicating the high potential for generalizability of the model. By utilizing this model, a significant amount of time and resources can be saved in formulation optimization without extensive primary testing of material properties.

Exogenous Application of Polycationic Nanobactericide on Tomato Plants Reduces the Candidatus Liberibacter Solanacearum Infection

Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and transmitted by the tomato psyllid Bactericera cockerelli. A polymeric water-dispersible nanobactericide (PNB) was evaluated against CaLso as a different alternative. PNB is a well-defined polycationic diblock copolymer designed to permeate into the vascular system of plants. Its assessment under greenhouse conditions was carried out with tomato plants previously infected with CaLso. Using a concentration as low as 1.0 mg L−1, a small but significant reduction in the bacterial load was observed by real-time qPCR. Thus, to achieve an ecologically friendly dosage and set an optimum treatment protocol, we performed experiments to determine the effective concentration of PNB to reduce ~65% of the initial bacterial load. In a first bioassay, a 40- or 70-fold increase was used to reach that objective. At this concentration level, other bioassays were explored to determine the effect as a function of time. Surprisingly, a real reduction in the symptoms was observed after three weeks, and there was a significant decrease in the bacterial load level (~98%) compared to the untreated control plants. During this period, flowering and formation of tomato fruits were observed in plants treated with PNB.

Solely aqueous formulation of hydrophobic cationic polymers for efficient gene delivery

Cationic polymers are promising gene delivery vectors due to their ability to bind and protect genetic material. The introduction of hydrophobic moieties into cationic polymers can further improve the vector efficiency, but common formulations of hydrophobic polymers involve harsh conditions such as organic solvents, impairing intactness and loading efficiency of the genetic material. In this study, a mild, aqueous formulation method for the encapsulation of high amounts of genetic material is presented. A well-defined pH-responsive hydrophobic copolymer, i.e. poly((n-butylmethacrylate)-co-(methylmethacrylate)-co-(2-(dimethylamino) ethylmethacrylate)), (PBMD) was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. Exploiting the pH-dependent solubility behavior of the polymer, stable pDNA loaded nanoparticles were prepared and characterized using analytical ultracentrifugation (AUC), cryo-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). This novel formulation approach showed high transfection efficiencies in HEK293T cells, while requiring 5- to 10-fold less pDNA compared to linear polyethylenimine (LPEI), in particular at short incubation times and in serum-containing media. Furthermore, the formulation was successfully adopted for siRNA and mRNA encapsulation and the commercially approved polymer Eudragit® E(PO/100). Overall, the aqueous formulation approach, accompanied by a tailor-made hydrophobic polymer and detailed physicochemical and application studies, led to improved gene delivery vectors with high potential for further applications.

Characterization of a library of vitamin A-functionalized polymethacrylate-based nanoparticles for siRNA delivery

A 60-membered library of vitamin A-functionalized P(MMA-stat-DMAEMA)-b-PPEGMA block copolymers was synthesized by RAFT polymerization. From these, nanoparticles containing genetic material were formulated and fully characterized.

Synthesis and self-assembly of photoacid-containing block copolymers based on 1-naphthol

Photoacids experience a strong increase in acidity when absorbing light and, hence, can be considered as molecular switches. The incorporation into amphiphilic block copolymers leads to novel stimuli-responsive materials with great potential.

Uptake and Intracellular Fate of Engineered Nanoparticles in Mammalian Cells: Capabilities and Limitations of Transmission Electron Microscopy-Polymer-Based Nanoparticles

In order to elucidate mechanisms of nanoparticle (NP)-cell interactions, a detailed knowledge about membrane-particle interactions, intracellular distributions, and nucleus penetration capabilities, etc. becomes indispensable. The utilization of NPs as additives in many consumer products, as well as the increasing interest of tailor-made nanoobjects as novel therapeutic and diagnostic platforms, makes it essential to gain deeper insights about their biological effects. Transmission electron microscopy (TEM) represents an outstanding method to study the uptake and intracellular fate of NPs, since this technique provides a resolution far better than the particle size. Additionally, its capability to highlight ultrastructural details of the cellular interior as well as membrane features is unmatched by other approaches. Here, a summary is provided on studies utilizing TEM to investigate the uptake and mode-of-action of tailor-made polymer nanoparticles in mammalian cells. For this purpose, the capabilities as well as limitations of TEM investigations are discussed to provide a detailed overview on uptake studies of common nanoparticle systems supported by TEM investigations. Furthermore, methodologies that can, in particular, address low-contrast materials in electron microscopy, i.e., polymeric and polymer-modified nanoparticles, are highlighted.

Dual pH and ultrasound responsive nanoparticles with pH triggered surface charge-conversional properties

A novel ultrasound responsive nanoparticle system with tunable surface charge-conversional properties is presented.

Retinol initiated poly(lactide)s: stability upon polymerization and nanoparticle preparation

The synthesis of retinol initiated polylactide (PLA) by ring opening polymerization (ROP) of l-lactide via in situ calcium alkoxide formation with all-trans-retinol and Ca[N(SiMe₃)₂]₂(THF)₂ is described.

Light-responsive terpolymers based on polymerizable photoacids

We present the synthesis and characterization of amphiphilic terpolymers containing photoacids based on 1-naphthol using reversible addition fragmentation chain transfer radical polymerization (RAFT).