Compatibilized Polymer Blends Based on PDLLA and PCL for Application in Bioartificial Liver

Tailored fabrication of biodegradable polymer/ Fe3O4 doped WO3 nano star-based porous membrane with enhanced photo fentonic activity for environmental remediation

The accelerated development of special-wetting polymeric materials with hierarchical pores for membrane applications is crucial to effectively separating water-soluble and insoluble pollutants, such as oily wastewater, emulsion, organic pollutants, and heavy metals. This pressing environmental and socioeconomic issue requires the implementation of effective remediation technologies. In this study, we successfully fabricated an environmentally friendly membrane with a flexible property by combining biopolymers and magnetic nanohybrids of iron oxide (Fe3O4)-doped tungsten oxide (WO3) through a thermal-induced phase separation process (TIPS). The resulting membrane exhibited a well-defined 3D-interconnected porous network structure when blending poly (ε-caprolactone)/poly (D,L-lactide) (PCL)/(PDLLA) in an 8:2 volume ratio. The Fe3O4@WO3 nanohybrids were synthesized using a hydrothermal process, resulting in a star-shaped morphology from the sea urchin-like WO3 clusters, which showed great potential to efficiently separate water/oil contamination and facilitate visible-light-driven photocatalytic degradation of organic dyes (MB, Rh B, BY, and CR) and photoreduction of hexavalent chromium (Cr (VI)). The obtained PCL/PDLLA/Fe3O4@WO3 nanocomposite membrane demonstrated hydrophobic properties, showing a water contact angle of 95 ± 2° and an excellent oil adsorption capacity of ∼4-4.5 g/g without fouling. The interconnected porous structure of the composite membrane enabled the efficient separation of emulsions (≥99.4 %) and achieved a high permeation flux of up to 1524 L m-2 h-1 under gravity separation. Overall, we obtained a novel high-performance composite material with specialized wetting properties, offering significant potential for effectively removing insoluble and soluble organic contaminants from wastewater.

Injectable niclosamide nanohybrid as an anti-SARS-CoV-2 strategy

COVID-19 is a rapidly evolving emergency, which necessitates scientific community to come up with novel formulations that could find quick relief to the millions affected around the globe. Remdesivir being the only injectable drug by FDA for COVID-19, it initially showed promising results, however, later on failed to retain its claims, hence rejected by the WHO. Therefore, it is important to develop injectable formulation that are effective and affordable. Here in this work, we formulated poly ethylene glycol (PEG) coated bovine serum albumin (BSA) stabilized Niclosamide (NIC) nanoparticles (NPs) (∼BSA-NIC-PEG NPs) as an effective injectable formulation. Here, serum albumin mediated strategy was proposed as an effective strategy to specifically target SARS-CoV-2, the virus that causes COVID-19. The in-vitro results showed that the developed readily water dispersible formulation with a particle size <120 nm size were well stable even after 3 weeks. Even though the in-vitro studies showed promising results, the in-vivo pharmaco-kinetic (PK) study in rats demands the need of conducting further experiments to specifically target the SARS-CoV-2 in the virus infected model. We expect that this present formulation would be highly preferred for targeting hypoalbuminemia conditions, which was often reported in elderly COVID-19 patients. Such studies are on the way to summarize its potential applications in the near future.

Toughened PLA-b-PCL-b-PLA triblock copolymer based biomaterials: effect of self-assembled nanostructure and stereocomplexation on the mechanical properties

The current research unfolds the effect of block lengths, microdomain morphology and stereocomplexation on the mechanical properties of PLA-b-PCL-b-PLA triblock copolymers where PCL is involved to improve the poor extensibility of PLA.

Active Ga-catalysts for the ring opening homo- and copolymerization of cyclic esters, and copolymerization of epoxide and anhydrides

A series of gallium complexes L12Ga4Me8 (1), L22Ga4Me8 (2), and L32Ga4Me8 (3) was synthesized by reaction of GaMe3 with Schiff base ligands L1-3H2 (L1H2 = 2,4-di-tert-butyl-6-{[(3-hydroxypropyl)imino]methyl}phenol; L2H2 = 2,4-dichloro-6-{[(3-hydroxypropyl)imino]methyl}phenol; L3H2 = 4-tert-butyl-2-{[(3-hydroxypropyl)imino]methyl}phenol) and characterized by 1H, 13C NMR, IR spectroscopy, elemental analysis and single crystal X-ray analysis (1, 2), proving their tetranuclear structure in the solid state. Complexes 1-3 showed good catalytic activity in the ring opening homopolymerization (ROP) and ring opening copolymerization (ROcoP) of lactide (LA) and ε-caprolactone (ε-CL) in the presence of benzyl alcohol (BnOH) in toluene at 100 °C, yielding polymers with the expected average molecular weights (Mn) and narrow molecular weight distributions (MWD), as well as a high isoselectivity for the ROP of rac-lactide (rac-LA), yielding isotactic-enriched PLAs with Pm values up to 0.78. Kinetic studies with complex 1 proved the first order dependence on monomer concentration, while mechanistic studies confirmed the coordination insertion mechanistic (CIM) pathway. Sequential addition of monomers gave well defined diblock copolymers of PCL-b-PLLA and PLLA-b-PCL, proving the living character of the polymerization reactions. The catalysts also showed perfect selectivity for the copolymerization of cyclohexene oxide (CHO) with both succinic anhydride (SA) and maleic anhydride (MA) in the presence of BnOH and produced >99% alternating block copolymers.

Bulk Organocatalytic Synthetic Access to Statistical Copolyesters from l-Lactide and ε-Caprolactone Using Benzoic Acid

The development of synthetic strategies to produce statistical copolymers based on l-lactide (l-LA) and ε-caprolactone (CL), denoted as P(LA- stat-CL), remains highly challenging in polymer chemistry. This is due to the differing reactivity of the two monomers during their ring-opening copolymerization (ROcP). Yet, P(LA- stat-CL) materials are highly sought after as they combine the properties of both polylactide (PLA) and poly(ε-caprolactone) (PCL). Here, benzoic acid (BA), a naturally occurring, cheap, readily recyclable, and thermally stable weak acid, is shown to trigger the organocatalyzed ring-opening copolymerization (OROcP) of l-LA and CL under solvent-free conditions at 155 °C, in presence of various alcohols as initiators, with good control over molar masses and dispersities (1.11 < Đ < 1.35) of the resulting copolyesters. Various compositions can be achieved, and the formation of statistical compounds is shown through characterization by ¹H, ¹³C, and diffusion ordered spectroscopy NMR spectroscopies and by differential scanning calorimetry, as well as through the determination of reactivity ratios ( r_LA = 0.86, r_CL = 0.86), using the visualization of the sum of squared residuals space method. Furthermore, this BA-OROcP process can be exploited to access metal-free PLA- b-P(LA- stat-CL)- b-PLA triblock copolymers, using a diol as an initiator. Finally, residual traces of BA remaining in P(LA- stat-CL) copolymers (<0.125 mol %) do not show any cytotoxicity toward hepatocyte-like HepaRG cells, demonstrating the safety of this organic catalyst.

Poly (lactic acid) blends: Processing, properties and applications

Poly (lactic acid) or polylactide (PLA) is a commercial biobased, biodegradable, biocompatible, compostable and non-toxic polymer that has competitive material and processing costs and desirable mechanical properties. Thereby, it can be considered favorably for biomedical applications and as the most promising substitute for petroleum-based polymers in a wide range of commodity and engineering applications. However, PLA has some significant shortcomings such as low melt strength, slow crystallization rate, poor processability, high brittleness, low toughness, and low service temperature, which limit its applications. To overcome these limitations, blending PLA with other polymers is an inexpensive approach that could also tailor the final properties of PLA-based products. During the last two decades, researchers investigated the synthesis, processing, properties, and development of various PLA-based blend systems including miscible blends of poly l-lactide (PLLA) and poly d-lactide (PDLA), which generate stereocomplex crystals, binary immiscible/miscible blends of PLA with other thermoplastics, multifunctional ternary blends using a third polymer or fillers such as nanoparticles, as well as PLA-based blend foam systems. This article reviews all these investigations and compares the syntheses/processing-morphology-properties interrelationships in PLA-based blends developed so far for various applications.

Catalytic metal-based systems for controlled statistical copolymerisation of lactide with a lactone

A comprehensive survey of the recent developments of metal-based catalysts for the ROcoP of lactide with another lactone is presented.

β-Pyridylenolate zinc catalysts for the ring-opening homo- and copolymerization of ε-caprolactone and lactides

Eleven zinc β-quinolylenolates with varying substituents have been synthesized, and some of these complexes are excellent catalysts for the ring-opening homo- and copolymerization of ε-CL and LAs.

Electrospun Nanofibrous P(DLLA-CL) Balloons as Calcium Phosphate Cement Filled Containers for Bone Repair: in Vitro and in Vivo Studies

The spinal surgeon community has expressed significant interest in applying calcium phosphate cement (CPC) for the treatment of vertebral compression fractures (VCFs) and minimizing its disadvantages, such as its water-induced collapsibility and poor mechanical properties, limiting its clinical use. In this work, novel biodegradable electrospun nanofibrous poly(d,l-lactic acid-ϵ-caprolactone) balloons (ENPBs) were prepared, and the separation, pressure, degradation, and new bone formation behaviors of the ENPBs when used as CPC-filled containers in vitro and in vivo were systematically analyzed and compared. CPC could be separated from surrounding bone tissues by ENPBs in vitro and in vivo. ENPB-CPCs (ENPBs serving as CPC-filled containers) exerted pressure on the surrounding bone microenvironment, which was enough to crush trabecular bone. Compared with the CPC implantation, ENPB-CPCs delayed the degradation of CPC (i.e., its water-induced collapsilibity). Finally, possible mechanisms behind the in vivo effects caused by ENPB-CPCs implanted into rabbit thighbones and pig vertebrae were proposed. This work suggests that ENPBs can be potentially applied as CPC-filled containers in vivo and provides an experimental basis for the clinical application of ENPBs for the treatment of VCFs. In addition, this work will be of benefit to the development of polymer-based medical implants in the future.

New advances in liver decellularization and recellularization: innovative and critical technologies

Techniques for producing decellularized scaffolds for use in liver tissue engineering are emerging as promising methods for tissue reconstruction. In this article, the authors present an overview of liver decellularization methods developed and applied in recent years. These include the widespread use of various perfusion methods for the generation of a 3D scaffold, which may function as a template for either cell recellularization or direct biological application. The authors evaluate methods for scaffold production and explore some factors that may affect the decellularization process. In addition to tissue engineering, this overview includes a description of other potential applications for a decellularized liver scaffold. The authors also introduce the concept of fabrication of fragile biomaterial architecture and finally review the cell types applied to liver scaffold engineering.

Electrospun Polycaprolactone Membrane Incorporated with Biosynthesized Silver Nanoparticles as Effective Wound Dressing Material

Biosynthesized silver nanoparticles (AgNPs) incorporated polycaprolactone (PCL) nanomembrane was prepared by electrospinning as a cost-effective nanocomposite for application as an antimicrobial agent against wound infection. The nanocomposite membrane was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis and Scanning Electron microscopy (SEM). The hydrophilicity analysis of electrospun membranes as evaluated by water contact angle measurement showed the change of hydrophobicity of PCL to hydrophilic upon incorporation of silver nanoparticles. Better mechanical properties were also observed for PCL membrane due to the incorporation of silver nanoparticles and are highly supportive to explore its biomedical applications. Further antibacterial analysis of silver nanoparticle-incorporated PCL membrane against common wound pathogens coagulase-negative Staphylococcus epidermidis and Staphylococcus haemolyticus showed remarkable activity. As biosynthesized AgNPs are least explored for clinical applications, the current study is a promising cost-effective method to explore the development of silver nanoparticle-based electrospun nanocomposite to resist wound-associated infection.

Ring-opening homo- and co-polymerization of lactides and ε-caprolactone by salalen aluminum complexes

Aluminum complexes of non-chiral-salalen ligands were investigated in the catalysis of ring-opening polymerization (ROP) of lactide and ε-caprolactone and in their copolymerization. The aluminum-salalen complexes were found to polymerize all varieties of lactide, namely: l-, d-, rac- and meso-lactide, and showed moderate productivities. rac-LA gave rise to isotactic polylactides (with Pm up to 72%), while meso-LA gave rise to heterotactic polylactides (with a Pm of 79%). An experiment was designed for distinguishing between chain-end control and enantiomorphic-site control combined with polymeryl exchange for the isotactic stereoblock microstructure observed for the PLA produced from rac-LA; it gave strong evidence for polymeryl exchange between propagating species. Finally, this class of catalysts promoted the copolymerization of ε-caprolactone and lactides. In particular, compound allowed controlled random copolymerization of ε-caprolactone and l-lactide.

Alkali-Metal Monophenolates with a Sandwich-Type Catalytic Center as Catalysts for Highly Isoselective Polymerization of rac-Lactide

Highly isoselective ring-opening polymerization (ROP) of rac-lactide is a challenge for sodium and potassium complexes under mild conditions. In this work, three sodium and potassium complexes with a sandwich-type catalytic center are highly active catalysts for the polymerization of rac-lactide and show high isoselectivities with P_m values of 0.72-0.82. The best isoselectivity of P_m = 0.82 is the highest value for alkali-metal complexes under mild conditions. The molecular weights of the obtained PLA are close to the theoretical values, and the molecular weight distributions are narrow.

Polylactide/Poly(ω-hydroxytetradecanoic acid) Reactive Blending: A Green Renewable Approach to Improving Polylactide Properties

A green manufacturing technique, reactive extrusion (REx), was employed to improve the mechanical properties of polylactide (PLA). To achieve this goal, a fully biosourced PLA based polymer blend was conceived by incorporating small quantities of poly(ω-hydroxytetradecanoic acid) (PC14). PLA/PC14 blends were compatibilized by transesterification reactions promoted by 200 ppm titanium tetrabutoxide (Ti(OBu)4) during REx. REx for 15 min at 150 rpm and 200 °C resulted in enhanced blend mechanical properties while minimizing losses in PLA molecular weight. SEM analysis of the resulting compatibilized phase-separated blends showed good adhesion between dispersed PC14 phases within the continuous PLA phase. Direct evidence for in situ synthesis of PLA-b-PC14 copolymers was obtained by HMBC and HSQC NMR experiments. The size of the dispersed phase was tuned by the screw speed to "tailor" the blend morphology. In the presence of 200 ppm Ti(OBu)4, inclusion of only 5% PC14 increased the elongation at break of PLA from 3 to 140% with only a slight decrease in the tensile modulus (3200 to 2900 MPa). Furthermore, PLA's impact strength was increased by 2.4× that of neat PLA for 20% PC14 blends prepared by REx. Blends of PLA and PC14 are expected to expand the potential uses of PLA-based materials.

Stereocomplex crystallite network in poly(d,l-lactide): formation, structure and the effect on shape memory behaviors and enzymatic hydrolysis of poly(d,l-lactide)

Rheological, mechanical properties and shape memory properties of PDLLA could be greatly improved through solution blending with sc-PLA.