Agent Poly Research Articles

Treg-enhancing and immunomodulating microgel scaffold promotes cell ingrowth and heart function recovery post-acute myocardial infarction in vivo

The ingrowth of endogenous cells into tissue scaffolds and modulation of Treg population take a pivotal function in restoring the structure and function of heart post-acute myocardial infarction (MI). However, the traditional hydrogels are failed to achieve such functions due to their critically small mesh size and inherent bioinertness. In this study, a Treg-regulated microgel scaffold (GTK-TK-drug) was prepared by inter-microgels assembly of microgels having cyclodextrin (CD) or adamantane (Ad) with a particle size of about 220 μm. The raw materials to obtain the microgels included gelatin methacryloyl (GelMA), reactive oxygen species (ROS)-responsive crosslinking agent poly(ethylene glycol)-thioketal-poly(ethylene glycol) (PEG-TK-PEG), ROS-responsive release prodrug aminooxyacetic acid (PEG-TK-AOA), PEG-CD or PEG-Ad, and photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). Quantitative real-time PCR (qPCR), cell counting kit-8, and immunofluorescence staining revealed the effectiveness of AOA for the differentiation of T cells into Treg and the ingrowth of cells in vitro and in vivo. During the short treatment of MI in vivo, the levels of plasma inflammatory factors, cardiomyocyte apoptosis and inflammatory cells were reduced significantly. In the long-term animal experiments, the recovery of cardiac function was significantly enhanced as characterized by echocardiography and the degree of myocardial fibrosis compared to the unassembled microgels control.

Evaluation of various monofunctional monomers for the development of fracture tough dental materials exhibiting a low crosslink density

3D printing of fracture tough dental materials that additionally exhibit excellent mechanical properties is challenging. Nowadays, most of the 3D printing dental materials contain a mixture of highly reactive dimethacrylates. The corresponding printed materials exhibit a high crosslink density and are particularly brittle. They are therefore not suitable for additive manufacturing of fracture tough denture bases. Recently, an efficient technology based on the combination of a urethane dimethacrylate macromonomer with a monofunctional monomer and a poly(ɛ-caprolactone)-polydimethylsiloxane-poly(ɛ-caprolactone) triblock copolymer was developed. Materials exhibiting a low crosslink density, excellent mechanical properties, and high fracture toughness were obtained. In this article, further developments of this highly efficient technology are described. A wide range of monofunctional monomers (both methacrylates and acrylates) was evaluated in this system. It was shown that the structure of the selected monofunctional monomer has a strong influence on the mechanical properties (flexural strength and modulus) as well as on the fracture toughness of the light cured materials. Thanks to the formation of nanostructures, a strong increase of fracture toughness was obtained upon addition of the toughening agent (poly(ɛ-caprolactone)-polydimethylsiloxane-poly(ɛ-caprolactone) triblock copolymer). The most promising materials were the ones based on the following monofunctional monomers: 2-phenoxyethyl methacrylate, (octahydro-4,7-methano-1H-indenyl)methyl acrylate, isobornyl acrylate, tetrahydrofurfuryl methacrylate and 4-tert-butylcyclohexyl acrylate. Indeed, these materials exhibited excellent mechanical properties (90.0 ± 3.8 MPa < flexural strength < 102.6 ± 4.7 MPa; 2402 ± 90 MPa < flexural modulus < 2714 ± 68 MPa) combined with high fracture toughness (1.89 ± 0.06 MPa m1/2 ≤ maximum stress intensity factor (Kmax) ≤ 2.18 ± 0.08 MPa m1/2; 418 ± 14 J m−2 ≤ work of fracture (Wf) ≤ 591 ± 25 J m−2). The measured Kmax and Wf were even significantly higher than the values reported for Probase Hot (Kmax = 1.44 ± 0.18 MPa m1/2; Wf = 270 ± 30 J m−2), a clinically proven and well-established PMMA based denture base material from Ivoclar. The successful DLP 3D printing of a monoblock denture using the most promising formulation confirmed the great potential of this technology for the development of 3D printing fracture tough denture bases.

Facile fabrication of lignin crosslinked hydrogel for cationic dye adsorption and antioxidant

Lignin, renowned for its abundance of hydroxyl groups, was utilized in three dimensions to fabricate a hydrogel matrix. In this study, the optimal conditions for the preparation of a lignin-crosslinked hydrogel and its potential for dye and antioxidant removal were investigated. The hydrogel was synthesized through a cross-linking reaction, with varying amounts of cross-linking agent (poly(ethylene glycol) diglycidyl ether) added to adjust for the lignin content. Chemical structure analysis of the lignin-crosslinked hydrogel was conducted using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy, confirming successful hydrogel formation. Additionally, thermal analysis revealed an increase in the maximum thermal decomposition temperature with increasing cross-linker content. The lignin cross-linked hydrogel demonstrated a significantly higher swelling ability at pH 7 compared to pH 3. The dye adsorption capacity of the lignin-crosslinked hydrogel, which was evaluated using crystal violet (CV), showed a maximum adsorption capacity of 106 mg∙g-1. The CV adsorption behavior followed Freundlich isotherms and pseudo-first-order kinetics. Moreover, the lignin-crosslinked hydrogel exhibited notable antioxidant activity, which was attributed to the phenolic hydroxyl groups of lignin macromolecules. Therefore, lignin-crosslinked hydrogels prepared using cross-linking agents have promising application potential in various fields.

Rosin-based self-healing functionalized composites with two-dimensional polyamide for antimicrobial and anticorrosion coatings

The design of polymer-based composites possessing good mechanical and self-healing properties remains a challenge in the development of high-performance self-healing materials. In this study, we used two-dimensional polyamide (2DPA), biomass rosin ester, and a dynamic crosslinking agent poly (urethane-urea) as raw materials, and prepared biomass rosin-based composites via in situ polymerization. The composites with 1 wt% 2DPA exhibited excellent self-healing properties (self-healing efficiency of 94 % after 24 h at 80 °C) and mechanical properties (tensile strength = 7.8 MPa). Moreover, the composites were applied to anticorrosion and antimicrobial coatings, which possessed excellent anticorrosion and antimicrobial properties. This study provides a new strategy for developing high-performance bio-based self-healing composites.

Methylene blue@silver nanoprisms conjugates as a strategy against Candida albicans isolated from balanoposthitis using photodynamic inactivation

Balanoposthitis can affect men in immunocompromised situations, such as HIV infection and diabetes. The main associated microorganism is Candida albicans, which can cause local lesions, such as the development of skin cracks associated with itching. As an alternative to conventional treatment, there is a growing interest in the photodynamic inactivation (PDI). It has been shown that the association of photosensitizers with metallic nanoparticles may improve the effectiveness of PDI via plasmonic effect. We have recently shown that the association of methylene blue (MB), a very known photosensitizer, with silver prismatic nanoplatelets (AgNPrs) improved PDI of a resistant strain of Staphylococcus aureus. To further investigate the experimental conditions involved in PDI improvement, in the present study, we studied the effect of MB concentration associated with AgNPrs exploring spectral analysis, zeta potential measurements, and biological assays, testing the conjugated system against C. albicans isolated from a resistant strain of balanoposthitis. The AgNPrs were synthesized through silver anisotropic seed growth induced by the anionic stabilizing agent poly(sodium 4-styrenesulfonate) and showed a plasmon band fully overlapping the MB absorption band. MB and AgNPrs were conjugated through electrostatic association and three different MB concentrations were tested in the nanosystems. Inactivation using red LED light (660 nm) showed a dose dependency in respect to the MB concentration in the conjugates. Using the highest MB concentration (100 µmol⋅L−1) with AgNPr, it was possible to completely inactivate the microorganisms upon a 2 min irradiation exposure. Analyzing optical changes in the conjugates we suggest that these results indicate that AgNPrs are enhancers of MB photodynamic action probably by a combined mechanism of plasmonic effect and reduction of MB dimerization. Therefore, MBAgNPrs can be considered a suitable choice to be applied in PDI of resistant microorganisms.

Using Borax as a Cross-Linking Agent in Poly(Vinyl Alcohol)/Hemp-Extracted Cellulose Hydrogels

This study focused on the preparation of hydrogels of poly (vinyl alcohol) and cellulose extracted from hemp fibers with the aid of borax as a cross-linking agent. Cellulose extracted from hemp fibers was initially dissolved in a mixed solution of urea and NaOH to obtain a cellulose solution. In the meantime, PVA was also dissolved in the urea and NaOH. These two solutions were mixed, and various loadings of borax were introduced. Moreover, the effect of borax loadings on equilibrium water content (EWC) and compression properties of the cross-linked hydrogels was investigated. The cross-linked hydrogels showed an EWC of 95.76% and a compression set of 9.71%, compared to those of the physical cross-linked hydrogels which had an EWC of 92.40% and a compression set of 29.96%. It was found that the chemically crosslinked hydrogels exhibited greater stability compared with physical ones owing to the stronger interaction induced by borax. Therefore, The PVA/cellulose hydrogels cross-linked with borax hold potential in various applications such as wound dressing, wastewater treatment, and agricultural fields.

Capping Agents Enable Well-Dispersed and Colloidally Stable Metallic Magnesium Nanoparticles.

Mg nanoparticles are an emerging plasmonic material due to Mg's abundance and ability to sustain size- and shape-dependent localized surface plasmon resonances across a broad range of wavelengths from the ultraviolet to the near infrared. However, Mg nanoparticles are colloidally unstable due to their tendency to aggregate and sediment. Nanoparticle aggregation can be inhibited by the addition of capping agents that impart surface charges or steric repulsion. Here, we report that the common capping agents poly(vinyl) pyrrolidone (PVP), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS) interact differently and have varied effects on the aggregation and colloidal stability of Mg nanoparticles. Nanoparticles synthesized in the presence of PVP showed improvements in colloidal stability and reduced aggregation, as observed by electron microscopy and optical spectroscopy. The binding of PVP was confirmed through infrared and X-ray photoelectron spectroscopy. The influence of PVP on the reduction of di-n-butyl magnesium was evaluated through analysis of particle size distribution and Mg yield as a function of reaction time, reducing agent, and temperature. Furthermore, the presence of PVP drastically changes the growth pattern of metallic Mg structures obtained from the reduction of the Grignard reagents butylmagnesium chloride and phenylmagnesium chloride by lithium naphthalenide: large polycrystalline aggregates and well-separated faceted nanoparticles grow without and with PVP, respectively. This study provides new synthetic routes that generate colloidally stable and well-dispersed Mg nanoparticles for plasmonic and other applications.

Syntheses, properties and mechanistic studies of 8-aminooctanoic acid-modified polyaspartic acid polymers for calcium scale inhibition

The anti-scaling agent poly(aspartic acidic) (PASP) polymers had became a hot research topic based on its peptide bond structures with degradation characteristics. However, it was difficult to control the chain length distributions of the synthesized products, which led to difficulty in determining the scaling mechanism for the peptide bond products. In this paper, PASP/8AC graft modified polymers with a narrow dispersity (Ð) and controllable chain lengths was synthesized via a simple two-step method, and 8-aminooctanoic acid (8AC) was introduced into the peptide bond structure of PASP with main chain lengths of 12. The effects of the side-chain lengths and functional groups on the scale inhibition mechanism were determined. The static scale inhibition results showed that the grafted products had significantly improved scale inhibition efficiencies at low concentrations and good temperature and time stabilities. The inhibition rate for CaSO4 scaling was increased by almost 60 % at a concentration of 3 mg/L. At 5 mg/L, the inhibition rate for CaCO3 scaling was increased by 36 %. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) showed that side chain length extensions improved calcium ion chelation by the PASP and increased calcium scale lattice distortion. This study verified the effects of side chains on PASP scale inhibition and its mechanism. This is of great importance in designing new green water treatment agents.

Antiviral and Antibacterial 3D-Printed Products Functionalised with Poly(hexamethylene biguanide).

Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray coatings at public facilities are the typical measures taken to protect people from coronaviruses and other pathogens. However, limitations of human resources and coating durability, as well as the safety of disinfectants used are the major concerns in society during a pandemic. Non-leachable antimicrobial agent poly(hexamethylene biguanide) (PHMB) was mixed into photocurable liquid resins to produce novel and tailor-made covers for public facilities via digital light processing, which is a popular 3D printing technique for satisfactory printing resolution. Potent efficacies of the 3D-printed plastics were achieved in standard antibacterial assessments against S. aureus, E. coli and K. pneumoniae. A total of 99.9% of Human coronavirus 229E was killed after being in contact with the 3D-printed samples (containing the promising PHMB formulation) for two hours. In an eight-week field test in Hong Kong Wetland Park, antibacterial performances of the specially designed 3D-printed covers analysed by environmental swabbing were also found to be satisfactory. With these remarkable outcomes, antimicrobial products prepared by digital light processing 3D printing can be regarded as a reliable solution to long-term infection prevention and control.

Exchangeable disulfide bond containing highly flexible epoxy vitrimers with shape‐memory, self‐healing, and UV shielding attributes

AbstractWith the rise in momentous resource wastage and severe environmental pollution, a viable path for sustainability is through the use of reprocessable and recyclable materials like vitrimers. Herein, we demonstrated the synthesis of dynamic disulfide‐containing epoxy resin by condensing an amide derivative of 2,2′‐dithiodibenzoic acid with epichlorohydrin. The aforementioned epoxy resin was cured utilizing the two bio‐based curing agents poly(amido amine) and cystamine to produce three distinct epoxy vitrimers. The use of reactive diluent reduced the generation of volatile organic compounds during the curing process. The existence of disulfide bond and aliphatic moiety in the epoxy vitrimers established high elongation at break with good tensile strength. Owing to the dynamic bond, the vitrimers exhibited self‐healing properties with a healing efficiency of 71.48% along with good shape memory abilities. Additionally, the disulfide bond dynamic exchange reaction allowed the polymer chain architecture to topologically reorganize, making them reprocessable and degradable. Moreover, these epoxy vitrimers have the ability to shield ultraviolet radiation as well as inhibits oxidation, and have good chemical resistance properties. The investigated epoxy thermoset thus provides a lot of potential for application as a durable thin film material.

Effects of stirring rate on morphology of aqueous RAFT emulsion PISA-derived block copolymer nanoparticles

The influence of stirring rate on nanoparticle morphology in aqueous RAFT emulsion PISA has been investigated.

Eu(III)-based polymeric nanoparticles as dual-emission turn-off sensor for anthrax biomarker detection

Anthrax is an acute infectious disease with high mortality caused by bacillus anthracis, which can severely harm human healthy. 2,6-pyridinedicarboxylic acid (DPA) is the main component and a major biomarker of bacillus anthracis. Therefore, it is essential to develop a sensitive and selective sensor for DPA detection. In this study, luminescent lanthanide nanoparticles, poly(PTEu)-PAA, were successfully synthesized by introducing Europium(III)-based complex and N-(4-(1,2,2-triphenylvinyl)phenyl)acrylamide (TPENA) to a hydrophilic macro-chain transfer agent poly(PEGMA)-PAA. The obtained poly(PTEu)-PAA nanoparticles were spherical with good dispersity, water stability and average diameters of approximately 443 nm. Furthermore, poly(PTEu)-PAA nanoparticles can act as a dual emission ‘‘turn-off’’ probe for detecting DPA in water. Upon addition of DPA, the emission of Eu(TTA)2(AA)phen and TPENA centers in polymeric nanoparticles were quenched with the detection limits (LODs) of 0.30 μM (at 618 nm) and 6.1 μM (at 455 nm), respectively, which was considerably lower than an infectious dosage of bacillus anthracis spores (60 μM) for a human being. Additionally, it showed high recoveries (92.50 %–102.45 %) in tap water, bovine serum, human serum and human urine samples. This is the first example of DPA sensor based on a dual-emission "turn-off" mechanism for Eu(III)-based polymeric nanoparticles, which presents a new avenue for detecting DPA.

Comparison of the elastic recovery and strain-in-compression of commercial and novel vinyl polysiloxane impression materials incorporating a novel crosslinking agent and a surfactant.

This study aims to formulate experimental vinylpolysiloxane (VPS) impression materials and compare their elastic recovery and strain-in-compressions with three commercial VPS materials (Aquasil, Elite, and Extrude). Five experimental materials (Exp), two hydrophobic (Exp-I and II) and three hydrophilic (Exp-III, IV and V) were developed. Exp 1 contained vinyl-terminated poly-dimethyl siloxane and a conventional cross-linking agent (poly methylhydrosiloxane), while Exp- II contained a novel cross-linking agent that is tetra-functional dimethyl-silyl-ortho-silicate (TFDMSOS). Exp III-V (hydrophilic materials) were formulated by incorporating different concentrations of non-ionic surfactant (Rhodasurf CET-2) into Exp II formulation. Measurement of elastic recovery and strain-in-compression for commercial and experimental materials were performed according to ISO4823 standard using the calibrated mechanical testing machine (Tinius Olsen). One-way analysis of variance (one-way ANOVA) and Tukey's post-hoc (HSD) test were used for statistical analysis and a p-value of ≤ 0.05 was considered significant. Exp-I has statistically similar values to commercial VPS. The Exp-II showed the highest elastic recovery, while % elastic recovery was reduced with the addition of the non-ionic surfactant (Rhodasurf CET-2). The % reduction was directly related to the concentration of Rhodasurf CET-2. In addition, Exp II had significantly higher strain-in-compression values compared to Exp-I and commercial materials. These values were further increased with the addition of a non-ionic surfactant (Rhodasurf CET-2) was added (Exp-III, IV and V).

Degradation products of the abuse deterrent agent Poly(ethylene) oxide under thermal manipulation conditions

Degradation products of the abuse deterrent agent Poly(ethylene) oxide under thermal manipulation conditions

Tannic acid as a crosslinking agent in poly(butylene adipate-co-terephthalate) composite films enhanced with carbon nanoparticles: Processing, characterization, and antimicrobial activities for food packaging

The disposal of plastics waste is currently a major environmental problem. Plastics are used frequently and in more variety in everyday life, which has an effect on the environment. As a result of the emissions of carbon dioxide caused by burning of non-biodegradable polymers like polyethylene, polypropylene, and polyvinyl chloride, there is a growing concern of a global warming. This article discusses the carbonization and activation of KOH to produce porous carbon nanoparticles (CNPs). The solution casting method was used to produced composites of poly(butylene adipate-co-terephthalate (PBAT) with CNPs and tannic acid (TA). PBAT composites employing CNPs as reinforcement and TA as a cross-linker. TA and CNPs have been taken into account in investigating the morphological and antimicrobial activities of PBAT-based composites. The mechanical strength of PBAT/TA/CNPs composites increased as a result to the strengthening characteristics of CNPs. The thermal characterization of PBAT/TA/CNPs composites was improved with TA and CNPs, based on thermogravimetric analysis (TGA). Contact angle measurements show that after reinforcement, PBAT/TA/CNPs composites became hydrophobic. In PBAT/TA/CNPs composites, the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) are reduced. The PBAT/TA/CNPs composites showed greater antimicrobial activity against the food-borne pathogenic microorganisms E. coli and S. aureus. Also, the results of food quality tests that PBAT/TA/CNPs composites used to have an improved shelf life for sliced carrot than control, commercial and PBAT film extending it from 1 to 12 days. The results indicated that PBAT/TA/CNPs composites would be suitable choices for materials to be used in food packaging.

Cross-linked self-healing polymers containing rosin moiety based on dynamic urea and multiple hydrogen bonds

In recent years, the use of renewable biomass resources to prepare self-healing polymers has become a hot research topic because of the shortage of fossil resources. Herein, a novel type of rosin-based cross-linked polymer (PR) with dynamic urea and multiple hydrogen bonds is fabricated by copolymerizing a rosin ester with a dynamic crosslinking agent poly(urethane-urea) through a simple UV-initiated reaction. Owing to its robustly dynamic bonds, the resulting PR has both good mechanical properties and ideal self-healing ability. Specifically, the PR with 25.4% biomass rosin reaches a tensile strength of up to 4.1 MPa, an elongation at break of 112%, and stress self-healing efficiency of 91.3% at 80 °C for 24 h. Remarkably, the PR with a glass transition temperature above room temperature exhibits good shape memory behavior and excellent weldability (afford 2500 g after healing at 80 °C for 5 h). Finally, by surface platinum spraying and pre-stretching treatment, strain sensors based on microcracking mechanisms are realized.

Electrochemical sensing platform with gold nanoparticles capped by PDDA for benzyl alcohol determination

An electrochemical sensor has been developed, by modifying screen-printed carbon devices (SPCE) with photochemically synthesized gold nanoparticles (AuNP), to determine benzyl alcohol, a preservative widely used in the cosmetic industry. To obtain the AuNP with the best properties for electrochemical sensing applications, the photochemical synthesis was optimized using chemometric tools. A response surface methodology based on central composite design was used to optimize the synthesis conditions, as irradiation time, and the concentrations of metal precursor and the capping/reducing agent (poly(diallyldimethylammonium) chloride, PDDA). The anodic current of benzyl alcohol on SPCE modified with the AuNP was used as response of the system. The best electrochemical responses were obtained using the AuNP generated by irradiating for 18 min a 7.20 times 10−4 mol L−1 AuCl4−-1.7% PDDA solution. The AuNP were characterized by transmission electron microscopy, cyclic voltammetry and dynamic light scattering. The nanocomposite-based sensor formed by the optimal AuNP (AuNP@PDDA/SPCE) was used to determine benzyl alcohol by linear sweep voltammetry in 0.10 mol L−1 KOH. The anodic current at + 0.017 ± 0.003 V (vs. AgCl) was used as analytical signal. Detection limit obtained under these conditions was 2.8 µg mL−1. The AuNP@PDDA/SPCE was applied to determine benzyl alcohol in cosmetic samples.Graphical

Functionalization of cellulose nanocrystals extracted from pineapple leaves as a UV-absorbing agent in poly(lactic acid).

The cinnamate functionalization of cellulose nanocrystals (Cin-CNCs) was investigated as a potential organic reinforcing and UV-shielding agent in polylactic acid (PLA) films. Acid hydrolysis was used to extract cellulose nanocrystals (CNCs) from pineapple leaves. Through esterification with cinnamoyl chloride, the cinnamate group was grafted onto the CNC surface and the resulting Cin-CNCs were incorporated in PLA films as reinforcing and UV-shielding agents. The PLA nanocomposite films were prepared using a solution-casting method and were tested for mechanical/thermal properties, gas permeability, and UV absorption. Importantly, the functionalization of cinnamate on CNCs substantially improved the dispersion of fillers on the PLA matrix. The PLA films containing 3 wt% Cin-CNCs exhibited high transparency and UV absorption in the visible region. On the other hand, PLA films filled with pristine CNCs did not exhibit any UV-shielding properties. The mechanical properties revealed that adding 3 wt% Cin-CNCs to PLA increased its tensile strength and Young's modulus by 70% and 37%, respectively, compared to neat PLA. In addition, the incorporation of Cin-CNCs substantially improved water vapor and oxygen permeability. At 3 wt% Cin-CNC addition, the water vapor and oxygen permeability of PLA films were reduced by 54% and 55%, respectively. This study demonstrated the great potential in utilizing Cin-CNCs as effective gas barriers, dispersible nanoparticles, and UV-absorbing, nano-reinforcing agents in PLA films.

Crowding-induced phase separation and gelling by co-condensation of PEG in NPM1-rRNA condensates

The crowdedness of the cell calls for adequate intracellular organization. Biomolecular condensates, formed by liquid-liquid phase separation of intrinsically disordered proteins and nucleic acids, are important organizers of cellular fluids. To underpin the molecular mechanisms of protein condensation, cell-free studies are often used where the role of crowding is not investigated in detail. Here, we investigate the effects of macromolecular crowding on the formation and material properties of a model heterotypic biomolecular condensate, consisting of nucleophosmin (NPM1) and ribosomal RNA (rRNA). We studied the effect of the macromolecular crowding agent poly(ethylene glycol) (PEG), which is often considered an inert crowding agent. We observed that PEG could induce both homotypic and heterotypic phase separation of NPM1 and NPM1-rRNA, respectively. Crowding increases the condensed concentration of NPM1 and decreases its equilibrium dilute phase concentration, although no significant change in the concentration of rRNA in the dilute phase was observed. Interestingly, the crowder itself is concentrated in the condensates, suggesting that co-condensation rather than excluded volume interactions underlie the enhanced phase separation by PEG. Fluorescence recovery after photobleaching measurements indicated that both NPM1 and rRNA become immobile at high PEG concentrations, indicative of a liquid-to-gel transition. Together, these results provide more insight into the role of synthetic crowding agents in phase separation and demonstrate that condensate properties determined in vitro depend strongly on the addition of crowding agents.

Synthesis of the Oil-Based Nanoblocker Poly(MMA-BMA-BA-St) and the Study of the Blocking Mechanism.

Well wall instability is one of the problems that seriously affect the efficiency of oil and gas drilling and extraction, and the economic losses caused by accidents due to well wall instability amount to billions of dollars every year. Aiming at the fact that well wall stabilization is the current technical difficulty of drilling shale gas horizontal wells with oil-based drilling fluids, the oil-based nanoplugging agent poly(MMA-BMA-BA-St) was synthesized by the Michael addition reaction with compounds such as styrene, methyl methacrylate, and butyl methacrylate as raw materials. The structure and characteristics of the oil-based nanoblocker poly(MMA-BMA-BA-St) were characterized by infrared spectroscopy, particle size analysis, and thermal weight loss analysis. The particle size distribution of poly(MMA-BMA-BA-St) is 80.56-206.61 nm, with an average particle size of 137.10 nm, and it can resist the high temperature of 372 °C. The effects of poly(MMA-BMA-BA-St) on the performance parameters of oil-based drilling fluids were investigated by rheological experiments, electrical stability tests, and HTHP filtration loss experiments. The results show that when poly(MMA-BMA-BA-St) is added at 0.5 wt %, it has less influence on the rheological parameters of drilling fluids, the breaking emulsion pressure remains basically unchanged, the stability of the drilling fluid is better, the dynamic-plastic ratio of the drilling fluid is higher than 0.27, the filtration loss is the lowest, and it shows good rock-carrying properties. The results of mud cake experiments and artificial lithology experiments show that poly(MMA-BMA-BA-St) has the best sealing effect, with a mud cake permeability of 1.12 × 10-4 mD and a sealing rate of 30.00% when added at 0.5 wt %; the artificial core permeability was 4.0 × 10-4 mD, and the sealing rate was 91.23%. Poly(MMA-BMA-BA-St) showed good sealing performance. The oil-based nanoplugging agent poly(MMA-BMA-BA-St) has good dispersion in oil-based drilling fluids and can enter the nanopore joints to form a dense plugging layer under the action of formation pressure to prevent the intrusion of drilling fluids, thus reducing the impact of drilling fluids on the formation, maintaining the stability of the well wall and reducing downhole complications.