Rapid prototyping and facile customization of conductive hydrogel bioelectronics based on all laser process.

Proper customization in size and shape is essential in implantable bioelectronics for stable bio-signal recording. Over the past decades, many researchers have heavily relied on conventional photolithography processes to fabricate implantable bioelectronics. Therefore, they could not avoid the critical limitation of high cost and complex processing steps to optimize bioelectronic devices for target organs with various sizes and shapes. Here, we propose rapid prototyping using all laser processes to fabricate customized bioelectronics. PEDOT:PSS is selectively irradiated by an ultraviolet (UV) pulse laser to form wet-stable conductive hydrogels that can softly interact with biological tissues (50 µm line width). The encapsulation layer is selectively patterned using the same laser source by UV-curing polymer networks (110 µm line width). For high stretchability (over 100%), mesh structures are made by the selective laser cutting process. Our rapid prototyping strategy minimizes the use of high-cost equipment, using only a single UV laser source to process the electrodes, encapsulation, and substrates that constitute bioelectronics without a photomask, enabling the prototyping stretchable microelectrode array with an area of 1 cm2 less than 10 min. We fabricated an optimized stretchable microelectrode array with low impedances (∼1.1 kΩ at 1 kHz) that can effectively record rat's cardiac signals with various health states.

Optimizing Process Parameters for Controlled Drug Delivery: A Quality by Design (QbD) Approach in Naltrexone Microspheres.

The formulation of microspheres involves a complex manufacturing process with multiple steps. Identifying the appropriate process parameters to achieve the desired quality attributes poses a significant challenge. This study aims to optimize the critical process parameters (CPPs) involved in the preparation of naltrexone microspheres using a Quality by Design (QbD) methodology. Additionally, the research aims to assess the drug release profiles of these microspheres under both in vivo and in vitro conditions. Critical process parameters (CPPs) and critical quality attributes (CQAs) were identified, and a Box-Behnken design was utilized to delineate the design space, ensuring alignment with the desired Quality Target Product Profile (QTPP). The investigated CPPs comprised polymer concentration, aqueous phase ratio to organic phase ratio, and quench volume. The microspheres were fabricated using the oil-in-water emulsion solvent extraction technique. Analysis revealed that increased polymer concentration was correlated with decreased particle size, reduced quench volume resulted in decreased burst release, and a heightened aqueous phase ratio to organic phase ratio improved drug entrapment. Upon analyzing the results, an optimal formulation was determined. In conclusion, the study conducted in vivo drug release testing on both the commercially available innovator product and the optimized test product utilizing an animal model. The integration of in vitro dissolution data with in vivo assessments presents a holistic understanding of drug release dynamics. The QbD approach-based optimization of CPPs furnishes informed guidance for the development of generic pharmaceutical formulations.

Synthesis, Structure and Antibacterial Activity of Two Novel Coordination Polymers Based on N,N'-bis(4-carbozvlbenzvl)-4-aminotoluene and Heterocyclic Ligand against S. aureus.

As the use of antibiotics increases, the increasing resistance of bacteria is the main reason for the reduced efficiency of antibacterial drugs, making the research of new antibacterial materials become new hot spot. In this article, two novel coordination polymers (CPs), namely, [Cd2(L)2(bibp)2]n (1) and [Ni(L)(bib)]n (2), where H2L = N,N'-bis(4-carbozvlbenzvl)-4-aminotoluene, bibp = 4,4'-bis(imidazol-1-yl)biphenyl, and bib = 1,3-bis(1-imidazoly)benzene, have been synthesized under solvothermal and hydrothermal condition. Structural clarification was performed through infrared spectrum and single-crystal X-ray diffraction analysis, while thermal analysis and XRD technology were used for the performance assessment of compounds 1 and 2. In addition, antibacterial performance experiments showed that compounds 1 and 2 have certain selectivity in their antibacterial properties and have good antibacterial properties against S. aureus. As the concentration of the compound increases, the inhibitory effect gradually strengthens, and when the concentration of the compound reaches 500 µg/mL and 400 µg/mL, the concentration of the S. aureus solution no longer increases and has been completely inhibited.

Development of Biocompatible Electrospun PHBV-PLLA Polymeric Bilayer Composite Membranes for Skin Tissue Engineering Applications.

Bilayer electrospun fibers aimed to be used for skin tissue engineering applications were fabricated for enhanced cell attachment and proliferation. Different ratios of PHBV-PLLA (70:30, 80:20, and 90:10 w/w) blends were electrospun on previously formed electrospun PHBV membranes to produce their bilayers. The fabricated electrospun membranes were characterized with FTIR, which conformed to the characteristic peaks assigned for both PHBV and PLLA. The surface morphology was evaluated using SEM analysis that showed random fibers with porous morphology. The fiber diameter and pore size were measured in the range of 0.7 ± 0.1 µm and 1.9 ± 0.2 µm, respectively. The tensile properties of the bilayers were determined using an electrodynamic testing system. Bilayers had higher elongation at break (44.45%) compared to the monolayers (28.41%) and improved ultimate tensile strength (7.940 MPa) compared to the PHBV monolayer (2.450 MPa). In vitro cytotoxicity of each of the scaffolds was determined via culturing MC3T3 (pre-osteoblastic cell line) on the membranes. Proliferation was evaluated using the Alamar Blue assay on days 3, 7, and 14, respectively. SEM images of cells cultured on membranes were taken in addition to bright field imaging to visually show cell attachment. Fluorescent nuclear staining performed with DAPI was imaged with an inverted fluorescent microscope. The fabricated bilayer shows high mechanical strength as well as biocompatibility with good cell proliferation and cell attachment, showing potential for skin substitute applications.

Investigating the in-vitro bioactivity, biodegradability and drug release behavior of the newly developed PES/HA/WS biocompatible nanocomposites as bone graft substitute.

The nucleation of carbonate-containing apatite on the biomaterials surface is regarded as a significant stage in bone healing process. In this regard, composites contained hydroxyapatite (Ca10(PO4)6(OH)2, HA), wollastonite (CaSiO3, WS) and polyethersulfone (PES) were synthesized via a simple solvent casting technique. The in-vitro bioactivity of the prepared composite films with different weight ratios of HA and WS was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The results indicated that the the surface of composites containing 2 wt% HA and 4 wt% WS was completely covered by a thick bone-like apatite layer, which was characterized by Grazing incidence X-ray diffraction, attenuated total reflectance-Fourier transform infrared spectrometer, field emission electron microscopy and energy dispersive X-ray analyzer (EDX). The degradation study of the samples showed that the concentration of inorganic particles could not influence the degradability of the polymeric matrix, where all samples expressed similar dexamethasone (DEX) release behavior. Moreover, the in-vitro cytotoxicity results indicated the significant cyto-compatibility of all specimens. Therefore, these findings revealed that the prepared composite films composed of PES, HA, WS and DEX could be regarded as promising bioactive candidates with low degradation rate for bone tissue engineering applications.

Advanced ethylene-absorbing and cushioning depending on the 3D porous-structured fruit packaging: Toward polyurethane foam manipulation using zein and soybean oil polyol substrates.

Fruits are essential sources of nutrients in our daily diet; however, their spoilage is often intensified by mechanical damage and the ethylene phytohormone, resulting in significant economic losses and exacerbating hunger issues. To address these challenges, this study presented a straightforward in situ synthesis protocol for producing Z/SOPPU foam, a 3D porous-structured fruit packaging. This innovative packaging material offered advanced ethylene-adsorbing and cushioning capabilities achieved through stirring, heating, and standing treatments. The results demonstrated that the Z/SOPPU foam, with its porous structure, served as an excellent packaging material for fruits, maintaining the intact appearance of tomatoes even after being thrown 72 times from a height of 1.5 m. Additionally, it exhibited desirable hydrophobicity (contact angle of 114.31 ± 0.82°), degradability (2.73 ± 0.88 % per 4 weeks), and efficient ethylene adsorption (adsorption rate of 13.2 ± 1.7 mg/m3/h). These remarkable characteristics could be attributed to the unique 3D micron-porous configuration, consisting of soybean oil polyol polyurethane foam for mechanical strain cushioning and zein for enhanced ethylene adsorption efficiency. Overall, this research offers an effective and original approach to the rational design and fabrication of advanced bio-based fruit packaging.

Nonenzymatic dual glucose sensing on boronic acid modified zeolitic imidazolate framework-67 nanoparticles for diabetes management.

For early diabetes identification and management, the progression of an uncomplicated and exceedingly responsive glucose testing technology is crucial. In this study, we present a new sensor incorporating a composite of metal organic framework (MOF) based on cobalt, coated with boronic acid to facilitate selective glucose binding. Additionally, we successfully employed a highly sensitive electro-optical immunosensor for the detection of subtle changes in concentration of the diabetes biomarker glycated haemoglobin (HbA1c), using zeolitic imidazolate framework-67 (ZIF-67) coated with polydopamine which further modified with boronic acid. Utilizing the polymerization characteristics of dopamine and the NH2 groups, a bonding structure is formed between ZIF-67 and 4-carboxyphenylboronic acid. ZIF-67 composite served as an effective substrate for immobilising 4-carboxyphenylboronic acid binding agent, ensuring precise and highly selective glucose identification. The sensing response was evaluated through both electrochemical and optical methods, confirming its efficacy. Under optimized experimental condition, the ZIF-67 based sensor demonstrated a broad detection range of 50-500 mg dL-1, a low limit of detection (LOD) of 9.87 mg dL-1 and a high correlation coefficient of 0.98. Furthermore, the 4-carboxyphenylboronic acid-conjugated ZIF-67-based sensor platform exhibited remarkable sensitivity and selectivity in optical-based detection for glycated haemoglobin within the clinical range of 4.7-11.3%, achieving a LOD of 3.7%. These findings highlight the potential of the 4-carboxyphenylboronic acid-conjugated ZIF-67-based electro-optical sensor as a highly sensitive platform for diabetes detection.

Combined effects of border irrigation and super-absorbent polymers on enzyme activity and microbial diversity of poplar rhizosphere soil.

Fast-growing poplar plantations are considered a great benefit to timber production, but water availability is a key factor limiting their growth and development, especially in arid and semi-arid ecosystems. Super-absorbent polymers facilitate more water retention in soil after rain or irrigation, and they are able to release water gradually during plant growth. This study aimed to examine the effects of reduced irrigation (60% and 30% of conventional border irrigation) co-applied with super-absorbent polymers (0, 40 kg/ha) on root exudates, enzyme activities, microbial functional diversity in rhizosphere soil, and volume increments in poplar (Populus euramericana cv. 'Neva'). The results showed that 60% border irrigation co-applied with super-absorbent polymers significantly increased the content of organic acids, amino acids and total sugars in the root exudates, and the activities of invertase, urease, dehydrogenase, and catalase in the rhizosphere soil in comparison to conventional border irrigation without super-absorbent polymers. Meanwhile, this treatment also enhanced the average well-color development, Shannon index, and McIntosh index, but decreased the Simpson index. Additionally, the average volume growth rate and relative water content of leaves reached their maximum using 60% irrigation with super-absorbent polymers, which was significantly higher than other treatments. However, using 30% irrigation with super-absorbent polymers, had a smaller effect on rhizosphere soil and volume growth than 60% irrigation with super-absorbent polymers. Therefore, using an appropriate water-saving irrigation measure (60% conventional border irrigation with super-absorbent polymers) can help to improve enzyme activities and microbial diversity in the rhizosphere soil while promoting the growth of poplar trees.

Receptor Targeting Using Copolymer-Modified Gold Nanoparticles for pCMV-Luc Gene Delivery to Liver Cancer Cells In Vitro.

The formulation of novel delivery protocols for the targeted delivery of genes into hepatocytes by receptor mediation is important for the treatment of liver-specific disorders, including cancer. Non-viral delivery methods have been extensively studied for gene therapy. Gold nanoparticles (AuNPs) have gained attention in nanomedicine due to their biocompatibility. In this study, AuNPs were synthesized and coated with polymers: chitosan (CS), and polyethylene glycol (PEG). The targeting moiety, lactobionic acid (LA), was added for hepatocyte-specific delivery. Physicochemical characterization revealed that all nano-formulations were spherical and monodispersed, with hydrodynamic sizes between 70 and 250 nm. Nanocomplexes with pCMV-Luc DNA (pDNA) confirmed that the NPs could bind, compact, and protect the pDNA from nuclease degradation. Cytotoxicity studies revealed that the AuNPs were well tolerated (cell viabilities > 70%) in human hepatocellular carcinoma (HepG2), embryonic kidney (HEK293), and colorectal adenocarcinoma (Caco-2) cells, with enhanced transgene activity in all cells. The inclusion of LA in the NP formulation was notable in the HepG2 cells, which overexpress the asialoglycoprotein receptor on their cell surface. A five-fold increase in luciferase gene expression was evident for the LA-targeted AuNPs compared to the non-targeted AuNPs. These AuNPs have shown potential as safe and suitable targeted delivery vehicles for liver-directed gene therapy.

Polydopamine/SWCNT Ink Functionalization of Silk Fabric to Obtain Electroconductivity at a Low Percolation Threshold.

This study presents the functionalization of silk fabric with SWCNT ink. The first step was the formation of a polydopamine (PDA) thin coating on the silk fabric to allow for effective bonding of SWCNTs. PDA formation was carried out directly on the fabric by means of polymerization of dopamine in alkali conditions. The Silk/PDA fabric was functionalized with SWCNT ink of different SWCNT concentrations by using the dip-coating method. IR and Raman analyses show that the dominant ß-sheet structure of silk fibroin after the functionalization process remains unchanged. The heat resistance is even slightly improved. The hydrophobic silk fabric becomes hydrophilic after functionalization due to the influence of PDA and the surfactant in SWCNT ink. The ink significantly changes the electrical properties of the silk fabric, from insulating to conductive. The volume resistance changes by nine orders of magnitude, from 2.4 × 1012 Ω to 2.3 × 103 Ω for 0.12 wt.% of SWCNTs. The surface resistance changes by seven orders of magnitude, from 2.1 × 1012 Ω to 2.4 × 105 Ω for 0.17 wt.% of SWCNTs. The volume and surface resistance thresholds are determined to be about 0.05 wt.% and 0.06 wt.%, respectively. The low value of the percolation threshold indicates efficient functionalization, with high-quality ink facilitating the formation of percolation paths through SWCNTs and the influence of the PDA linker.

Impact of Nebulization on the Physicochemical Properties of Polymer-Lipid Hybrid Nanoparticles for Pulmonary Drug Delivery.

Nanoparticles (NPs) have shown significant potential for pulmonary administration of therapeutics for the treatment of chronic lung diseases in a localized and sustained manner. Nebulization is a suitable method of NP delivery, particularly in patients whose ability to breathe is impaired due to lung diseases. However, there are limited studies evaluating the physicochemical properties of NPs after they are passed through a nebulizer. High shear stress generated during nebulization could potentially affect the surface properties of NPs, resulting in the loss of encapsulated drugs and alteration in the release kinetics. Herein, we thoroughly examined the physicochemical properties as well as the therapeutic effectiveness of Infasurf lung surfactant (IFS)-coated PLGA NPs previously developed by us after passing through a commercial Aeroneb® vibrating-mesh nebulizer. Nebulization did not alter the size, surface charge, IFS coating and bi-phasic release pattern exhibited by the NPs. However, there was a temporary reduction in the initial release of encapsulated therapeutics in the nebulized compared to non-nebulized NPs. This underscores the importance of evaluating the drug release kinetics of NPs using the inhalation method of choice to ensure suitability for the intended medical application. The cellular uptake studies demonstrated that both nebulized and non-nebulized NPs were less readily taken up by alveolar macrophages compared to lung cancer cells, confirming the IFS coating retention. Overall, nebulization did not significantly compromise the physicochemical properties as well as therapeutic efficacy of the prepared nanotherapeutics.

Advancements in Polymer-Assisted Layer-by-Layer Fabrication of Wearable Sensors for Health Monitoring.

Recent advancements in polymer-assisted layer-by-layer (LbL) fabrication have revolutionized the development of wearable sensors for health monitoring. LbL self-assembly has emerged as a powerful and versatile technique for creating conformal, flexible, and multi-functional films on various substrates, making it particularly suitable for fabricating wearable sensors. The incorporation of polymers, both natural and synthetic, has played a crucial role in enhancing the performance, stability, and biocompatibility of these sensors. This review provides a comprehensive overview of the principles of LbL self-assembly, the role of polymers in sensor fabrication, and the various types of LbL-fabricated wearable sensors for physical, chemical, and biological sensing. The applications of these sensors in continuous health monitoring, disease diagnosis, and management are discussed in detail, highlighting their potential to revolutionize personalized healthcare. Despite significant progress, challenges related to long-term stability, biocompatibility, data acquisition, and large-scale manufacturing are still to be addressed, providing insights into future research directions. With continued advancements in polymer-assisted LbL fabrication and related fields, wearable sensors are poised to improve the quality of life for individuals worldwide.

Analyzing the Thermal Characteristics of Three Lining Materials for Plantar Orthotics.

INTRODUCTION: The choice of materials for covering plantar orthoses or wearable insoles is often based on their hardness, breathability, and moisture absorption capacity, although more due to professional preference than clear scientific criteria. An analysis of the thermal response to the use of these materials would provide information about their behavior; hence, the objective of this study was to assess the temperature of three lining materials with different characteristics. MATERIALS AND METHODS: The temperature of three materials for covering plantar orthoses was analyzed in a sample of 36 subjects (15 men and 21 women, aged 24.6 ± 8.2 years, mass 67.1 ± 13.6 kg, and height 1.7 ± 0.09 m). Temperature was measured before and after 3 h of use in clinical activities, using a polyethylene foam copolymer (PE), ethylene vinyl acetate (EVA), and PE-EVA copolymer foam insole with the use of a FLIR E60BX thermal camera. RESULTS: In the PE copolymer (material 1), temperature increases between 1.07 and 1.85 °C were found after activity, with these differences being statistically significant in all regions of interest (p < 0.001), except for the first toe (0.36 °C, p = 0.170). In the EVA foam (material 2) and the expansive foam of the PE-EVA copolymer (material 3), the temperatures were also significantly higher in all analyzed areas (p < 0.001), ranging between 1.49 and 2.73 °C for EVA and 0.58 and 2.16 °C for PE-EVA. The PE copolymer experienced lower overall overheating, and the area of the fifth metatarsal head underwent the greatest temperature increase, regardless of the material analyzed. CONCLUSIONS: PE foam lining materials, with lower density or an open-cell structure, would be preferred for controlling temperature rise in the lining/footbed interface and providing better thermal comfort for users. The area of the first toe was found to be the least overheated, while the fifth metatarsal head increased the most in temperature. This should be considered in the design of new wearables to avoid excessive temperatures due to the lining materials.

Therapeutic activity and biodistribution of a nano-sized polymer-dexamethasone conjugate intended for the targeted treatment of rheumatoid arthritis.

Rheumatoid arthritis is a chronic inflammatory autoimmune disease caused by alteration of the immune system. Current therapies have several limitations and the use of nanomedicines represents a promising strategy to overcome them. By employing a mouse model of adjuvant induced arthritis, we aimed to evaluate the biodistribution and therapeutic effects of glucocorticoid dexamethasone conjugated to a nanocarrier based on biocompatible N-(2-hydroxypropyl) methacrylamide copolymers. We observed an increased accumulation of dexamethasone polymer nanomedicines in the arthritic mouse paw using non-invasive fluorescent in vivo imaging and confirmed it by the analysis of tissue homogenates. The dexamethasone conjugate exhibited a dose-dependent healing effect on arthritis and an improved therapeutic outcome compared to free dexamethasone. Particularly, significant reduction of accumulation of RA mediator RANKL was observed. Overall, our data suggest that the conjugation of dexamethasone to a polymer nanocarrier by means of stimuli-sensitive spacer is suitable strategy for improving rheumatoid arthritis therapy.

Semiconducting Polymers Based on Asymmetric Thiadiazoloquinoxaline for Augmented In Vivo NIR-II Photoacoustic Imaging.

A photoacoustic (PA) imaging technique using the second near-infrared (NIR-II) window has attracted more and more attention because of its merits of deeper penetration depth and higher signal-to-noise (S/N) ratio than that using the first near-infrared (NIR-I) one. However, the design and development of high-performance PA imaging contrast agents in the NIR-II window is still a challenge. A semiconducting polymer, constructed by asymmetric units, exhibits regiorandom characteristics that effectively increase the distortion of the backbone. This increase in the degree of twist can regulate the twisted intramolecular charge transfer (TICT) effect, resulting in an enhancement of the PA signal. In this paper, an asymmetric structural acceptor strategy is developed to improve the PA signals of the resulting semiconducting polymer (PATQ-MP) in the NIR-II window with improved brightness, higher S/N ratio, and better photothermal conversion efficiency compared to polymers with the same main-chain structure containing a symmetric acceptor. DFT analysis showed that PATQ-MP containing an asymmetric acceptor monomer had a larger dihedral angle, which effectively improved the PA signal intensity by enhancing the TICT effect. The PEG-encapsulated PATQ-MP nanoparticles exhibit promising performance in the PA imaging of mouse tumors in vivo, demonstrating the clear identification of microvessels as small as 100 µm along with rapid metabolism within a span of 5 h. Therefore, this work provides a unique molecular design strategy for improving the signal intensity of PA imaging in the NIR-II window.

Dextran Macroinitiator for Synthesis of Polysaccharide-b-Polypeptide Block Copolymers via NCA Ring-Opening Polymerization.

Synthesis of polysaccharide-b-polypeptide block copolymers represents an attractive goal because of their promising potential in delivery applications. Inspired by recent breakthroughs in N-carboxyanhydride (NCA) ring-opening polymerization (ROP), we present an efficient approach for preparation of a dextran-based macroinitiator and the subsequent synthesis of dextran-b-polypeptides via NCA ROP. This is an original approach to creating and employing a native polysaccharide macroinitiator for block copolymer synthesis. In this strategy, regioselective (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation of the sole primary alcohol located at the C-6 position of the monosaccharide at the nonreducing end of linear dextran results in a carboxylic acid. This motif is then transformed into a tetraalkylammonium carboxylate, thereby generating the dextran macroinitiator. This macroinitiator initiates a wide range of NCA monomers and produces dextran-b-polypeptides with a degree of polymerization (DP) of the polypeptide up to 70 in a controlled manner (D < 1.3). This strategy offers several distinct advantages, including preservation of the original dextran backbone structure, relatively rapid polymerization, and moisture tolerance. The dextran-b-polypeptides exhibit interesting self-assembly behavior. Their nanostructures have been investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and adjustment of the structure of block copolymers allows self-assembly of spherical micelles and worm-like micelles with varied diameters and aspect ratios, revealing a range of diameters from 60 to 160 nm. Moreover, these nanostructures exhibit diverse morphologies, including spherical micelles and worm-like micelles, enabling delivery applications.

Chiral coordination polymer nanowires boost radiation-induced in situ tumor vaccination.

Radiation-induced in situ tumor vaccination alone is very weak and insufficient to elicit robust antitumor immune responses. In this work, we address this issue by developing chiral vidarabine monophosphate-gadolinium nanowires (aAGd-NWs) through coordination-driven self-assembly. We elucidate the mechanism of aAGd-NW assembly and characterize their distinct features, which include a negative surface charge, ultrafine topography, and right-handed chirality. Additionally, aAGd-NWs not only enhance X-ray deposition but also inhibit DNA repair, thereby enhancing radiation-induced in situ vaccination. Consequently, the in situ vaccination induced by aAGd-NWs sensitizes radiation enhances CD8+ T-cell-dependent antitumor immunity and synergistically potentiates the efficacy immune checkpoint blockade therapies against both primary and metastatic tumors. The well-established aAGd-NWs exhibit exceptional therapeutic capacity and biocompatibility, offering a promising avenue for the development of radioimmunotherapy approaches.

New Insights on Solvent-Induced Changes in Refractivity and Specific Rotation of Poly(propylene oxide) Systems Extracted from Channeled Spectra.

Investigation of chiroptical polymers in the solution phase is paramount for designing supramolecular architectures for photonic or biomedical devices. This work is devoted to the case study of poly(propylene oxide) (PPO) optical activity in several solvents: benzonitrile, carbon disulfide, chloroform, ethyl acetate, and p-dioxane. To attain information on the interactions in these systems, rheological testing was undertaken, showing distinct variations of the rheological parameters as a function of the solvent type. These aspects are also reflected in the refractive index dispersive behavior, from which linear and non-linear optical properties are extracted. To determine the circular birefringence and specific rotation of the PPO solutions, the alternative method of the channeled spectra was employed. The spectral data were correlated with the molecular modeling of the PPO structural unit in the selected solvents. Density functional theory (DFT) computational data indicated that the torsional potential energy-related to the O1-C2-C3-O4 dihedral angle from the polymer repeating unit-was hindered in solvation environments characterized by high polarity and the ability to interact via hydrogen bonding. This was in agreement with the optical characterization of the samples, which indicated a lower circular birefringence and specific rotation for the solutions of PPO in ethyl acetate and p-dioxane. Also, the shape of optical rotatory dispersion curves was slightly modified for PPO in these solvents compared with the other ones.

Effect of Poly(propylene carbonate) on Properties of Polylactic Acid-Based Composite Films.

To enrich the properties of polylactic acid (PLA)-based composite films and improve the base degradability, in this study, a certain amount of poly(propylene carbonate) (PPC) was added to PLA-based composite films, and PLA/PPC-based composite films were prepared by melt blending and hot-press molding. The effects of the introduction of PPC on the composite films were analyzed through in-depth studies on mechanical properties, water vapor and oxygen transmission rates, thermal analysis, compost degradability, and bacterial inhibition properties of the composite films. When the introduction ratio coefficient of PPC was 30%, the tensile strength of the composite film increased by 19.68%, the water vapor transmission coefficient decreased by 14.43%, and the oxygen transmission coefficient decreased by 18.31% compared to that of the composite film without PPC, the cold crystallization temperature of the composite film increased gradually from 96.9 °C to 104.8 °C, and PPC improved the crystallization ability of composite film. The degradation rate of the composite film with PPC increased significantly compared to the previous one, and the degradation rate increased with the increase in the PPC content. The degradation rate was 49.85% and 46.22% faster on average than that of the composite film without PPC when the degradation was carried out over 40 and 80 days; the composite film had certain inhibition, and the maximum diameter of the inhibition circle was 2.42 cm. This study provides a strategy for the development of PLA-based biodegradable laminates, which can promote the application of PLA-based laminates in food packaging.

Polymer Coatings Affect Transport and Remobilization of Colloidal Activated Carbon in Saturated Sand Columns: Implications for In Situ Groundwater Remediation.

Colloidal activated carbon (CAC) is an emerging technology for the in situ remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS). In assessing the long-term effectiveness of a CAC barrier, it is crucial to evaluate the potential of emplaced CAC particles to be remobilized and migrate away from the sorptive barrier. We examine the effect of two polymer stabilizers, carboxymethyl cellulose (CMC) and polydiallyldimethylammonium chloride (PolyDM), on CAC deposition and remobilization in saturated sand columns. CMC-modified CAC showed high mobility in a wide ionic strength (IS) range from 0.1 to 100 mM, which is favorable for CAC delivery at a sufficient scale. Interestingly, the mobility of PolyDM-modified CAC was high at low IS (0.1 mM) but greatly reduced at high IS (100 mM). Notably, significant remobilization (release) of deposited CMC-CAC particles occurred upon the introduction of solution with low IS following deposition at high IS. In contrast, PolyDM-CAC did not undergo any remobilization following deposition due to its favorable interactions with the quartz sand. We further elucidated the CAC deposition and remobilization behaviors by analyzing colloid-collector interactions through the application of Derjaguin-Landau-Verwey-Overbeek theory, and the inclusion of a discrete representation of charge heterogeneity on the quartz sand surface. The classical colloid filtration theory was also employed to estimate the travel distance of CAC in saturated columns. Our results underscore the roles of polymer coatings and solution chemistry in CAC transport, providing valuable guidelines for the design of in situ CAC remediation with maximized delivery efficiency and barrier longevity.