Interfacial Conformation of Hydrophilic Polyphosphoesters Affects Blood Protein Adsorption

Rubber-like and Antifouling Poly(trimethylene carbonate-ethylphosphonate) Copolymers with Tunable Hydrolysis

Controlling the degradation and cell interaction of polymer materials is vital for numerous applications. Transitioning from enzymatic to nonenzymatic hydrolysis offers precise control over degradation processes. In this study, we synthesized high molar mass poly(trimethylene carbonate) (PTMC)-polyphosphonate copolymers to achieve distinctive antifouling and controlled degradation properties. 2-Ethyl-2-oxo-1,3,2-dioxaphospholane (EtPPn) is copolymerized with trimethylene carbonate (TMC) to random P(TMC-co-EtPPn) copolymers through ring-opening copolymerization, utilizing Sn(Oct)2 as the catalyst. Copolymers with molar masses reaching up to Mn = 218 kg/mol and molar mass dispersities of D̵ < 1.9 are obtained. To maintain hydrophobicity, 10 and 20 mol % of hydrophilic phosphonate units are incorporated into PTMC-copolymers. While copolymers with 10 mol % EtPPn display mechanical properties akin to the homopolymer PTMC, a deviation in elongation at break and yield strength results when 20 mol % EtPPN is incorporated. PTMC-PPE copolymers demonstrate antifouling behavior, i.e., cell repulsion for human mesenchymal stem cells (hMSCs) and inhibited enzymatic degradation by lipase in contrast to PTMC-homopolymers. Conversely, P(TMC-co-EtPPn) undergo abiotic hydrolytic degradation with hydrolysis rates increasing with increasing phosphonate contents. In conclusion, copolymerization with EtPPn enables the switch from enzymatic PTMC degradation to adjustable hydrolytic degradation, offering controlled stabilities of such copolymers in the desired applications.

Advanced Biomaterials Derived from Functional Polyphosphoesters: Synthesis, Properties, and Biomedical Applications

Polyphosphoesters (PPEs) represent an innovative class of biodegradable polymers, with the phosphate ester serving as the core repeating unit of their polymeric backbone. Recently, biomaterials derived from functionalized PPEs have garnered significant interest in biomedical applications because of their commendable biocompatibility, biodegradability, and the capacity for functional modification. This review commences with a brief overview of synthesis methodologies and the distinctive properties of PPEs, including thermoresponsiveness, degradability, stealth effect, and biocompatibility. Subsequently, the review delves into the latest applications of PPEs-based nanocarriers for drug or gene delivery and PPEs-based polymeric prodrugs and scaffolds in the biomedical field, presenting several illustrative examples for each application. By encapsulating the advancements of recent years, this review aims to offer an enhanced understanding and serve as a reference for the synthesis and biomedical applications of functional PPEs.

Holden, Donahue ND, Green DE, Frickenstein AN, Mettenbrink EM, Schwemley TA, Francek ER, Haddad M, Hossen MN, Mukherjee S, Wu S, DeAngelis PL, Wilhelm S. Nanoparticle Surface Engineering with Heparosan Polysaccharide Reduces Serum Protein Adsorption and Enhances Cellular Uptake

Nanoparticle modification with poly(ethylene glycol) (PEG) is a widely used surface engineering strategy in nanomedicine. However, since the artificial PEG polymer may adversely impact nanomedicine safety and efficacy, alternative surface modifications are needed. Here, we explored the "self" polysaccharide heparosan (HEP) to prepare colloidally stable HEP-coated nanoparticles, including gold and silver nanoparticles and liposomes. We found that the HEP-coating reduced the nanoparticle protein corona formation as efficiently as PEG coatings upon serum incubation. Liquid chromatography-mass spectrometry revealed the protein corona profiles. Heparosan-coated nanoparticles exhibited up to 230-fold higher uptake in certain innate immune cells, but not in other tested cell types, than PEGylated nanoparticles. No noticeable cytotoxicity was observed. Serum proteins did not mediate the high cell uptake of HEP-coated nanoparticles. Our work suggests that HEP polymers may be an effective surface modification technology for nanomedicines to safely and efficiently target certain innate immune cells.

Amphiphilic Polyphosphonate Copolymers as New Additives for PDMS-Based Antifouling Coatings

Poly(ethyl ethylene phosphonate)-based methacrylic copolymers containing polysiloxane methacrylate (SiMA) co-units are proposed as surface-active additives as alternative solutions to the more investigated polyzwitterionic and polyethylene glycol counterparts for the fabrication of novel PDMS-based coatings for marine antifouling applications. In particular, the same hydrophobic SiMA macromonomer was copolymerized with a methacrylate carrying a poly(ethyl ethylene phosphonate) (PEtEPMA), a phosphorylcholine (MPC), and a poly(ethylene glycol) (PEGMA) side chain to obtain non-water soluble copolymers with similar mole content of the different hydrophilic units. The hydrolysis of poly(ethyl ethylene phosphonate)-based polymers was also studied in conditions similar to those of the marine environment to investigate their potential as erodible films. Copolymers of the three classes were blended into a condensation cure PDMS matrix in two different loadings (10 and 20 wt%) to prepare the top-coat of three-layer films to be subjected to wettability analysis and bioassays with marine model organisms. Water contact angle measurements showed that all of the films underwent surface reconstruction upon prolonged immersion in water, becoming much more hydrophilic. Interestingly, the extent of surface modification appeared to be affected by the type of hydrophilic units, showing a tendency to increase according to the order PEGMA < MPC < PEtEPMA. Biological tests showed that Ficopomatus enigmaticus release was maximized on the most hydrophilic film containing 10 wt% of the PEtEP-based copolymer. Moreover, coatings with a 10 wt% loading of the copolymer performed better than those containing 20 wt% for the removal of both Ficopomatus and Navicula, independent from the copolymer nature.

In Situ Label-Free Study of Protein Adsorption on Nanoparticles

Improving the design of nanoparticles for use as drug carriers or biosensors requires a better understanding of the protein-nanoparticle interaction. Here, we present a new tool to investigate this interaction in situ and without additional labeling of the proteins and/or nanoparticles. By combining nonresonant second-harmonic light scattering with a modified Langmuir model, we show that it is possible to gain insight into the adsorption behavior of blood proteins, namely fibrinogen, human serum albumin, and transferrin, onto negatively charged polystyrene nanoparticles. The modified Langmuir model gives us access to the maximum amount of adsorbed protein, the apparent binding constant, and Gibbs free energy. Furthermore, we employ the method to investigate the influence of the nanoparticle size on the adsorption of human serum albumin and find that the amount of adsorbed protein increases more than the surface area per nanoparticle for larger diameters.

Origins of Clustering of Metalate-Extractant Complexes in Liquid-Liquid Extraction

Effective and energy-efficient separation of precious and rare metals is very important for a variety of advanced technologies. Liquid-liquid extraction (LLE) is a relatively less energy intensive separation technique, widely used in separation of lanthanides, actinides, and platinum group metals (PGMs). In LLE, the distribution of an ion between an aqueous phase and an organic phase is determined by enthalpic (coordination interactions) and entropic (fluid reorganization) contributions. The molecular scale details of these contributions are not well understood. Preferential extraction of an ion from the aqueous phase is usually correlated with the resulting fluid organization in the organic phase, as the longer-range organization increases with metal loading. However, it is difficult to determine the extent to which organic phase fluid organization causes, or is caused by, metal loading. In this study, we demonstrate that two systems with the same metal loading may impart very different organic phase organizations and investigate the underlying molecular scale mechanism. Small-angle X-ray scattering shows that the structure of a quaternary ammonium extractant solution in toluene is affected differently by the extraction of two metalates (octahedral PtCl₆^2- and square-planar PdCl₄^2-), although both are completely transferred into the organic phase. The aggregates formed by the metalate-extractant complexes (approximated as reverse micelles) exhibit a more long-range order (clustering) with PtCl₆^2- compared to that with PdCl₄^2-. Vibrational sum frequency generation spectroscopy and complementary atomistic molecular dynamics simulations on model Langmuir monolayers indicate that the two metalates affect the interfacial hydration structures differently. Furthermore, the interfacial hydration is correlated with water extraction into the organic phase. These results support a strong relationship between the organic phase organizational structure and the different local hydration present within the aggregates of metalate-extractant complexes, which is independent of metalate concentration.

Structural basis for high-pressure improvement in depolymerization of interfacial protein from RFRS meat batters in relation to their solubility

High-pressure processing (HPP) can modify the construction of interfacial proteins (IPs) to improve the properties of reduced-fat and reduced-salt (RFRS) meat batters. In this study, the relationship between the construction of IPs and their solubility at fat droplet/water interface in RFRS meat batters with HPP treatments was investigated. When 200 MPa for 2 min was applied, the IPs exhibited the highest solubility due to a high concentration of absorbed myosin with the content of random coil 65.62%, but the particle diameter was in reverse. The microscopy revealed the depolymerization of IPs occurred at low pressure, while macromolecular aggregates were produced as the cross-linking of IPs to some degree at pressure ≥ 200 MPa. This phenomenon was supported by the result of SDS-PAGE and the sulfhydryl of IPs. In conclusion, the HPP induced solubility alteration of IPs was achieved by modifying their construction through adjusting the secondary structures and regulating bond interactions.

Cyclic ethylene phosphates with (CH2)nCOOR and CH2CONMe2 substituents: synthesis and mechanistic insights of diverse reactivity in aryloxy-Mg complex-catalyzed (co)polymerization

Herein we present a comparative study of the reactivity of ethylene phosphates with –O(CH2)nCOOMe (n = 1–3, 5), –CH2COOtBu, –OCHMeCOOMe, and –OCH2CONMe2 substituents in BHT-Mg catalyzed ROP.

Bioactive 3D porous cobalt-doped alginate/waterborne polyurethane scaffolds with a coral reef-like rough surface for nerve tissue engineering application

Bioactive 3D porous cobalt-doped alginate/waterborne polyurethane scaffolds with a coral reef-like rough surface were prepared for nerve tissue engineering application.

Modulation of Platelet-Surface Activation: Current State and Future Perspectives

Modulation of platelet-surface activation is important for many biomedical applications such as in vivo performance, platelet storage, and acceptance of an implant. Reducing platelet-surface activation is challenging because they become activated immediately after short contact with nonphysiological surfaces. To date, controversies and open questions in the field of platelet-surface activation still remain. Here, we review state-of-the-art approaches in inhibiting platelet-surface activation, mainly focusing on modification, patterning, and methodologies for characterization of the surfaces. As a future perspective, we discuss how the combination of biochemical and physiochemical strategies together with the topographical modulations would assist in the search for an ideal nonthrombogenic surface.

Polyphosphoestered Nanomedicines with Tunable Surface Hydrophilicity for Cancer Drug Delivery

The surface hydrophilicity of nanoparticles has a major impact on their biological fates. Ascertaining the correlation between nanoparticle surface hydrophilicity and their biological behaviors is particularly instructive for future nanomedicine design and their antitumor efficacy optimization. Herein, we designed a series of polymeric nanoparticles based on polyphosphoesters with well-controlled surface hydrophilicity in the molecular level and systemically evaluated their biological behaviors. The results demonstrated that high surface hydrophilicity preferred lower protein absorption, better stability, longer blood circulation, and higher tumor accumulation but lower cellular uptake. Upon encapsulation of drugs, nanoparticles with high hydrophilicity showed an excellent antitumor therapeutic efficacy in both primary and metastatic tumors as compared to the relatively hydrophobic ones. Further analyses revealed that the superior antitumor outcome was attributed to the balance of tumor accumulation and cellular uptake, demonstrating the particular importance of nanoparticle surface hydrophilicity regulation on the antitumor efficacy. Our work provides a potent guideline for a rational designation on the surface hydrophilicity of nanoparticles for cancer treatment optimization.

Hydrophilic polyphosphoester-conjugated fluorinated chlorin as an entirely biodegradable nano-photosensitizer for reliable and efficient photodynamic therapy

An entirely biodegradable nano-photosensitizer platform (PPE-FP2) was fabricated by conjugating the photosensitizer TFPC to hydrophilic polyphosphoesters (PPEs) for efficiently liberating photosensitizers at the tumor site. The complete biodegradability of PPE-FP2 avoided residual nanoparticles in vivo after therapy, realizing reliable and effective photodynamic therapy.

Both Poly(ethylene glycol) and Poly(methyl ethylene phosphate) Guide Oriented Adsorption of Specific Proteins

Developing new functional biomaterials requires the ability to simultaneously repel unwanted and guide wanted protein adsorption. Here, we systematically interrogate the factors determining the protein adsorption by comparing the behaviors of different polymeric surfaces, poly(ethylene glycol) and a poly(phosphoester), and five different natural proteins. Interestingly we observe that, at densities comparable to those used in nanocarrier functionalization, the same proteins are either adsorbed (fibrinogen, human serum albumin, and transferrin) or repelled (immunoglobulin G and lysozyme) by both polymers. However, when adsorption takes place, the specific surface dictates the amount and orientation of each protein.