Polysaccharide nanoporous structures are suitable for various applications, ranging from biomedical scaffolds to adsorption materials, owing to their biocompatibility and large surface areas. Pectin, in particular, can create 3D nanoporous structures in aqueous solutions by binding with calcium cations and creating nanopores by phase separation; this process involves forming hydrogen bonds between alcohols and pectin chains in water and alcohol mixtures and the resulting penetration of alcohols into calcium-bound pectin gels. However, owing to the dehydration and condensation of polysaccharide chains during drying, it has proven to be challenging to maintain the 3D nanoporous structure without using a freeze-drying process or supercritical fluid. Herein, we report a facile method for creating polysaccharide-based xerogels, involving the co-evaporation of water with a nonsolvent (e.g., a low-molecular-weight hydrophobic alcohol such as isopropyl or n-propyl alcohol) at ambient conditions. Experiments and coarse-grained molecular dynamics simulations confirmed that salt-induced phase separation and hydrogen bonding between hydrophobic alcohols and pectin chains were the dominant processes in mixtures of pectin, water, and hydrophobic alcohols. Furthermore, the azeotropic evaporation of water and alcohol mixed in approximately 1:1 molar ratios was maintained during the natural drying process under ambient conditions, preventing the hydration and aggregation of the hydrophilic pectin chains. These results introduce a simple and convenient process to produce 3D polysaccharide xerogels under ambient conditions.

This study presents a nanohybrid that simultaneously improves both photothermal (PT) and photodynamic (PD) effects for cancer therapy. The conjugated polymer nanoparticle (CPN) comprises of p-type conjugated polymer as a photosensitizer, charge donor, and PT agent, n-type conjugated polymer as a charge acceptor and PD agent, and Au nanoparticles (NPs) as a PT agent. This nanohybrid is assembled through a film dispersion process using a hydrophobically modified phospholipid, producing a high yield of uniform hybrid NPs in a short timeframe, and displays exceptional photothermal and photodynamic effects, when activated at a single near-infrared wavelength. Photophysical analysis indicates that the inclusion of Au NPs enhances nonradiative exciton relaxation, while the incorporation of a n-type conjugated polymer boosts photoinduced charge transfer and potentially contributes to the charge-recombination mediated triplet-state formation for an enhanced generation of reactive oxygen species. During phototherapy, the nanohybrid demonstrates the most effective suppression of primary tumor growth and significantly boosts anti-tumor immune responses owing to its simultaneous photothermal and photodynamic effects. Furthermore, when combined with immune checkpoint inhibitors, nanohybrid treatment minimizes tumor sizes while maximizing survival rates in mice. Thus, the nanohybrid represents a promising nanoplatform for combination phototherapy in cancer treatment.

Since the spread of COVID-19 worldwide, antimicrobial, and antiviral chemicals have been developed and widely used to create an effective antibacterial biomaterials and textiles based on unique nanofibers. However, the leaching of antimicrobial agents from the nanofibers in use due to their instability ultimately remains a concern. Therefore, a full investigation of the durability of antibacterial agents is required for safe and compatible utilization. This review summarizes recent work on the combination of antimicrobial agents and nanofibers by first describing the fabrication of functionalized antimicrobial nanofibers and then addressing the durability of antimicrobial agents on these nanofibers. In particular, the intrinsic structure of antimicrobial nanofibers, the compatibility of antimicrobial agents with specific nanofibers, and the self-assembly process are described. In addition, the antimicrobial activity of the nanofibers is reviewed, with a focus on factors affecting the bacterial/viral removal efficiency and their interaction mechanisms. The present review also summarizes the criteria required to ensure the stability of antimicrobial agents for nanofiber applications. Special attention is given to durable antimicrobial agents for washable antibacterial textiles. Finally, this paper reviews future directions and emerging technologies for antimicrobial nanofiber applications. This review thus highlights the importance of durability for the reuse of antibacterial nanofibers and textiles while maintaining their microbial effectiveness.

We report that conjugated polymer nanoparticles (CPNs) coated with polyethylene glycols (PEGs) exhibit photothermal and photodynamic capabilities according to molecular ordering in their assembly structures. CPN-PEGs were made using three different methods: a dispersion process of phase-separated film assemblies of a conjugated polymer and a phospholipid-conjugated PEG (CPN-I), a dispersion process of a conjugated polymer and a phospholipid followed by surface conjugation with PEGs (CPN-II), and a miniemulsification of the conjugated polymer and the phospholipid-conjugated PEG. Our findings revealed that the ordered molecular assembly structures in CPN-I and CPN-II increased intermolecular interactions and decreased the optical band gap, promoting nonradiative exciton relaxation via the energy-gap law’s internal conversion mechanism and rationalizing CPN-I’s shorter singlet exciton lifetime (13 ps). Meanwhile, CPN-III with a disordered structure generated more singlet oxygen than CPN-I and CPN-II, indicating increased triplet exciton generation upon the polaron recombination. Our findings present that the photothermal and photodynamic properties of CPNs are obviously dependent on the assembly structure order and that CPNs with an ordered assembly of conjugated backbones have a stronger photothermal effect, whereas those with a disordered structure have a better photodynamic effect.

We assemble a film of a phosphocholine-based lipid and a crystalline conjugated polymer using hydrophobic interactions between the alkyl tails of the lipid and alkyl side chains of the polymer, and demonstrated its selective gas adsorption properties and the polymer's improved light absorption properties. We show that a strong attractive interaction between the polar lipid heads and CO2 was responsible for 6 times more CO2 being adsorbed onto the assembly than N2, and that with repeated CO2 adsorption and vacuuming procedures, the assembly structures of the lipid-polymer assembly were irreversibly changed, as demonstrated by in situ grazing-incidence X-ray diffraction during the gas adsorption and desorption. Despite the disruption of the lipid structure caused by adsorbed polar gas molecules on polar head groups, gas adsorption could promote orderly alkyl chain packing by inducing compressive strain, resulting in enhanced electron delocalization of conjugated backbones and bathochromic light absorption. The findings suggest that merging the structures of the crystalline functional polymer and lipid bilayer is a viable option for solar energy-converting systems that use conjugated polymers as a light harvester and the polar heads as CO2-capturing sites.

In this study, intermolecular interactions were investigated for increasing the charge carrier mobility of organic field-effect transistors (OFETs) based on a conjugated polymer. A diketopyrrolopyrrole (DPP)-based conjugated polymer widely used in OFETs, i.e., poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (PDPP-DTT), was assembled using 2-bromobenzaldehyde (2-BBA) and used as an active layer for OFETs. Morphological characterization and analysis for non-covalent intermolecular interactions suggested that the halogen bonding between the bromide of 2-BBA and electron-donor group of PDPP-DTT and the association between the electron-acceptor group in 2-BBA and sulfur of PDPP-DTT improved the hole transfer in the PDPP-DTT-based OFETs. The intermolecular interactions resulting from the addition of 2-BBA contributed to the two-fold enhancement of the hole mobility, two-order increase in magnitude of the current on/off ratio, and 50% decrease in the threshold voltage of the OFETs based on PDPP-DPP.

Porous polysaccharides have recently attracted attention due to their porosity, abundance, and excellent properties such as sustainability and biocompatibility, thereby resulting in their numerous applications. Recent years have seen a rise in the number of studies on the utilization of polysaccharides such as cellulose, chitosan, chitin, and starch as aerogels due to their unique performance for the fabrication of porous structures. The present review explores recent progress in porous polysaccharides, particularly cellulose and chitosan, including their synthesis, application, and future outlook. Since the synthetic process is an important aspect of aerogel formation, particularly during the drying step, the process is reviewed in some detail, and a comparison is drawn between the supercritical CO2 and freeze drying processes in order to understand the aerogel formation of porous polysaccharides. Finally, the current applications of polysaccharide aerogels in drug delivery, wastewater, wound dressing, and air filtration are explored, and the limitations and outlook of the porous aerogels are discussed with respect to their future commercialization.

Sensitive strain sensors (an important component of soft robotics, wearable devices, and biomedical electronics) with high sensitivity, stretchability, and long-term stability are still challenging. A sensitive, stretchable, and sustainable sensor using poly(3,4-ethylenedioxythiophene) ( PEDOT) coated cellulose nanocrystals (CNC) with poly(vinyl alcohol)/glycerol (PVA/Gly) composite is proposed. The low cost and sustainable PEDOT coated CNC with high aspect ratio lowered the electrical percolation threshold that significantly improved the electrical conductivity leading to better sensitivity (gauge factor = 21.25) compared to the PEDOT applied film without CNC (gauge factor = 9.35). The exceptional stretchability of up to 500% and a low Young's modulus with long-term stability exceeding 3 months are due to the glycerol plasticizer. The fabricated sensors possessed outstanding real-time strain sensing capability for a series of human motions, including complex joint bending motions, subtle muscle motions, wrist pulse, and excellent self-healing ability. This effective green strategy for preparing a highly stretchable conductive composite addresses current limitations in strain sensor preparation and offers a sustainable approach to sensor design and development.

Smart textiles based on conjugated polymers have been highlighted as promising fabrics that can intelligently respond to environmental stimuli based on the electrical properties of polymer semiconductors. However, there has been limited interest in the photothermal properties of conjugated polymers that can be applied to smart textiles. We prepared nanoparticles by assembling a conjugated polymer with a fatty acid via an emulsion process and nanocomposite fibers by distributing the conjugated polymer nanoparticles in a polyacrylonitrile matrix. We then fabricated the textiles using the fibers. The resulting fabrics based on nanocomposite fibers show a temperature increase to 50 °C in 10 min under white light irradiation because of efficient photothermal conversion by the conjugated polymer light harvester, while the temperature of a pristine polyacrylonitrile fabric increases to only 35 °C. In addition, excellent antimicrobial activity was confirmed by a 99.9% decrease in the populations of Staphylococcus aureus and Escherichia coli over 24 h because of the effect of the fatty acid in the nanocomposite films and fabrics. Furthermore, the fabric showed efficient durability after a laundry test, suggesting the usefulness of these smart textiles based on conjugated polymer nanoparticles for practical applications.

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 ± 2.4 nm and 2.5 ± 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines.

We report that the ordered structure in the assemblies of iron oxide nanoparticles in conjugated polymer nanoparticles is the key to achieve better properties to realize multimodal theranostic agents for magnetic resonance and photoacoustic imaging. Hybrid nanoparticles of a conjugated polymer (PCPDTBT), a phospholipid (D8PE) with a primary amine polar head, and iron oxide (Fe3O4) nanoparticles were prepared by a phase-separated film shattering process by varying the iron oxide concentration while maintaining a fixed mixing ratio of PCPDTBT and D8PE. Notably, the hybrid nanoparticles assembled at a molar mixing ratio of 1:1:0.8 (PCPDTBT/D8PE/Fe3O4) exhibited the shortest transversal relaxation time, T2, and a photoacoustic signal 22 times higher than that obtained at the 1:1:0 mixing ratio. Structural analysis by X-ray diffraction together with the measurements of energy transfer by transient absorption spectroscopy confirmed that the structural ordering of these hybrid nanoparticles was responsible for their enhanced photoacoustic and magnetic properties.

We prepared conjugated polymer nano-ellipsoids (CPNs) via emulsification of chloroform phase using the octanoic acid (OA) in dimethyl formamide (DMF), followed by the removal of chloroform by heating. The resulting CPN DMF solutions were thoroughly mixed with polyurethane (PU) DMF solutions to form composite films upon solvent removal, with uniformly distributed CPNs due to hydrogen bonds between PU matrix and the CPNs. Superior photothermal and antibacterial properties of the PU:CPN composite films were observed, presenting the usefulness of CPNs as an efficient light harvester and thermal storage material, and the OA as an antibacterial material for multifunctional fiber applications. (C) 2018 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cydopenta[2,1-b;3,4-b'-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-sn-glycero-3-phosphocholine (D8PC). The pi-pi stacked structure of PCPDTBT is significantly enhanced when the ratio-of D8PC increases in both dried and water exposed film. We also show that the amount of D8PC is at least 2.5 times larger than that of PCPDTBT to wrap the conjugated polymer chain, and the direct retrieval of atomistic details is achieved through back-mapping from the morphology of CG. Finally, we confirmed that conjugated backbones inside the nanoparticles were completely shielded from the aqueous solution by the dense layers of alkyl chains, resulting in remarkably enhanced chain packing. These simulated results are correlated with experimentally observed structure through UV-vis-near-infrared (UV-vis-NIR) spectrometry, scanning electron microscopy (SEM), particle size analyzer (PSA), transmission electron microscopy (TEM), and grazing-incidence X-ray diffraction (GIRD).