Inducing pH control over the critical micelle concentration of zwitterionic surfactants via polyacids adsorption: Effect of chain length and structure

Evaluation of co-foaming agents for enhanced removal of per-and polyfluoroalkyl substances (PFAS) by foam fractionation

Foam fractionation has emerged as a leading method to remove per- and polyfluoroalkyl substances (PFAS) from impacted aqueous matrices due to the low cost and rapid PFAS removal. Although foam fractionation has been shown to efficiently remove long-chain PFAS, cationic co-foaming agents are often necessary to improve the removal of short-chain PFAS. However, many of the best performing co-surfactants used for short-chain PFAS removal, such as cetyltrimethylammonium bromide (CTAB), are of concern due to their potential toxicity and low biodegradability. The objective of this study was to evaluate the performance of lower-toxicity co-foaming agents for enhanced removal of both long-chain and short-chain PFAS compounds. Six candidate co-foaming agents were tested in a laboratory-scale foam fractionation system that consisted of a 60-cm acrylic column equipped with a 0.5-μm air diffusor, injection and sampling ports, and a vacuum-assisted foam collection reservoir. Based on the results of experiments conducted using water containing long- and short-chain PFAS, a naturally derived zwitterionic surfactant derived from Shea butter was identified as the most promising alternative co-foaming agent. Subsequent experiments demonstrated that the shea butter derived surfactant (SBDS) performance was improved by lowering the pH to 3, and under these conditions, SBDS was able to remove greater than 99.5 % of the PFAS from groundwater collected from AFFF-impacted military installations. These findings demonstrate the efficacy of a low-toxicity, biodegradable co-foaming agent as a replacement for traditional cationic surfactants, which are known to be toxic and persistent in the environment.

How To Correct Erroneous Symmetry-Breaking in Coarse-Grained Constant-pH Simulations

The constant-pH Monte Carlo method is a popular algorithm to study acid-base equilibria in coarse-grained simulations of charge regulating soft matter systems including weak polyelectrolytes and proteins. However, the method suffers from systematic errors in simulations with explicit ions, which lead to a symmetry-breaking between chemically equivalent implementations of the acid-base equilibrium. Here, we show that this artifact of the algorithm can be corrected a-posteriori by simply shifting the pH-scale. We present two analytical methods as well as a numerical method using Widom insertion to obtain the correction. By numerically investigating various sample systems, we assess the range of validity of the analytical approaches and show that the Widom approach always leads to consistent results, even when the analytical approaches fail. Overall, we provide practical guidelines on how to use constant-pH simulations to avoid systematic errors, including cases where special care is required, such as polyampholytes and proteins.

pH responsive and zwitterionic micelle for enhanced cellular uptake and antitumor performance

The side effects of small molecule chemotherapeutic drugs (SMCD) have brought great pain to the cancer patients. Many nanodrug carriers can relieve the shortcomings of SMCD, but they have complex synthesis processes and lack biodegradability. To overcome both problems, we synthesized a pH responsive biodegradable zwitterionic molecules (EK-D) by linking zwitterionic polypeptide (EK7) and dodecyl acrylate through a simple click reaction. Subsequently, doxorubicin (DOX) was physically encapsulated within the EK-D micelles to produce EK-D-DOX micelles, and polyethylene glycol monooleate (POO) employed as a comparative group for the preparation of POO-DOX micelles. The results show that EK-D-DOX micelles have good aqueous stability and anti-protein non-specific adsorption performance at pH 7.4, but EK-D-DOX micelles aggregate under the condition of pH = 5.5 due to the biodegradability of EK-D. The tumor cell uptake rate of EK-D-DOX micelles is higher than that of POO-DOX micelles and free DOX, which makes EK-D-DOX micelles the highest cytotoxic. Additionally, EK-D-DOX micelles release more DOX in a slightly acidic environment than at pH 7.4, and the release of DOX reaches a significant cumulative value of 75.20 % under pH conditions of 5.5. More importantly, EK-D-DOX micelles exhibit superior in vivo tumor inhibitory efficacy compared to free DOX, resulting in a remarkable tumor inhibition rate of 95.7 %. EK-D-DOX micelles not only have lower biological toxicity to normal tissues than free DOX, but also have a longer blood circulation time in mice. The method of EK-D-DOX micelles preparation represents a new method to prepare biodegradable zwitterionic nanodrug.

Recent progress in stimuli-responsive polymeric micelles for targeted delivery of functional nanoparticles

Stimuli-responsive polymeric micelles have emerged as a revolutionary approach for enhancing the in vivo stability, biocompatibility, and targeted delivery of functional nanoparticles (FNPs) in biomedicine. This article comprehensively reviews the preparation methods of these polymer micelles, detailing the innovative strategies employed to introduce stimulus responsiveness and surface modifications essential for precise targeting. We delve into the breakthroughs in utilizing these micelles to selectively deliver various FNPs including magnetic nanoparticles, upconversion nanoparticles, gold nanoparticles, and quantum dots, highlighting their transformative impact in the biomedical realm. Concluding, we present an insight into the current research landscape, addressing the challenges at hand, and envisioning the future trajectory in this burgeoning domain. Join us as we navigate the exciting confluence of polymer science and nanotechnology in reshaping biomedical solutions.