Linear, Mannitol-Based Poly(anhydride-esters) with High Ibuprofen Loading and Anti-Inflammatory Activity

A systematic review on utilization of biodiesel-derived crude glycerol in sustainable polymers preparation

With the rapid development of biodiesel, biodiesel-derived glycerol has become a promising renewable bioresource. The key to utilizing this bioresource lies in the value-added conversion of crude glycerol. While purifying crude glycerol into a pure form allows for diverse applications, the intricate nature of this process renders it costly and environmentally stressful. Consequently, technology facilitating the direct utilization of unpurified crude glycerol holds significant importance. It has been reported that crude glycerol can be bio-transformed or chemically converted into high-value polymers. These technologies provide cost-effective alternatives for polymer production while contributing to a more sustainable biodiesel industry. This review article describes the global production and quality characteristics of biodiesel-derived glycerol and investigates the influencing factors and treatment of the composition of crude glycerol including water, methanol, soap, matter organic non-glycerol, and ash. Additionally, this review also focused on the advantages and challenges of various technologies for converting crude glycerol into polymers, considering factors such as the compatibility of crude glycerol and the control of unfavorable factors. Lastly, the application prospect and value of crude glycerol conversion were discussed from the aspects of economy and environmental protection. The development of new technologies for the increased use of crude glycerol as a renewable feedstock for polymer production will be facilitated by the findings of this review, while promoting mass market applications.

4D Printable Salicylic Acid Photopolymers for Sustained Drug Releasing, Shape Memory, Soft Tissue Scaffolds

3D printing of pharmaceuticals offers a unique opportunity for long-term, sustained drug release profiles for an array of treatment options. Unfortunately, this approach is often limited by physical compounding or processing limitations. Modification of the active drug into a prodrug compound allows for seamless incorporation with advanced manufacturing methods that open the door to production of complex tissue scaffold drug depots. Here we demonstrate this concept using salicylic acids with varied prodrug structures for control of physical and chemical properties. The role of different salicylic acid derivatives (salicylic acid, bromosalicylic allyl ester, iodosalicylic allyl ester) and linker species (allyl salicylate, allyl 2-(allyloxy)benzoate, allyl 2-(((allyloxy)carbonyl)oxy)benzoate) were investigated using thiol-ene cross-linking in digital light processing (DLP) 3D printing to produce porous prodrug tissue scaffolds containing more than 50% salicylic acid by mass. Salicylic acid photopolymer resins were all found to be highly reactive (solidification within 5 s of irradiation at λ = 405 nm), while the cross-linked solids display tunable thermomechanical behaviors with low glass transition temperatures (Tgs) and elastomeric behaviors, with the carbonate species displaying an elastic modulus matching that of adipose tissue (approximately 65 kPa). Drug release profiles were found to be zero order, sustained release based upon hydrolytic degradation of multilayered scaffolds incorporating fluorescent modeling compounds, with release rates tuned through selection of the linker species. Cytocompatibility in 2D and 3D was further demonstrated for all species compared to polycarbonate controls, as well as salicylic acid-containing composites (physical incorporation), over a 2-week period using murine fibroblasts. The use of drugs as the matrix material for solid prodrug tissue scaffolds opens the door to novel therapeutic strategies, longer sustained release profiles, and even reduced complications for advanced medicine.

Harnessing the power of polyol-based polyesters for biomedical innovations: synthesis, properties, and biodegradation

Polyesters based on polyols have emerged as promising biomaterials for various biomedical applications, such as tissue engineering, drug delivery systems, and regenerative medicine, due to their biocompatibility, biodegradability, and versatile physicochemical properties. This review article provides an overview of the synthesis methods, performance, and biodegradation mechanisms of polyol-based polyesters, highlighting their potential for use in a wide range of biomedical applications. The synthesis techniques, such as simple polycondensation and enzymatic polymerization, allow for the fine-tuning of polyester structure and molecular weight, thereby enabling the tailoring of material properties to specific application requirements. The physicochemical properties of polyol-based polyesters, such as hydrophilicity, crystallinity, and mechanical properties, can be altered by incorporating different polyols. The article highlights the influence of various factors, such as molecular weight, crosslinking density, and degradation medium, on the biodegradation behavior of these materials, and the importance of understanding these factors for controlling degradation rates. Future research directions include the development of novel polyesters with improved properties, optimization of degradation rates, and exploration of advanced processing techniques for fabricating scaffolds and drug delivery systems. Overall, polyol-based polyesters hold significant potential in the field of biomedical applications, paving the way for groundbreaking advancements and innovative solutions that could revolutionize patient care and treatment outcomes.

Polyanhydride Chemistry

Polyanhydrides (PAs) are a class of synthetic biodegradable polymers employed as controlled drug delivery vehicles. They can be synthesized and scaled up from low-cost starting materials. The structure of PAs can be manipulated synthetically to meet desirable characteristics. PAs are biocompatible, biodegradable, and generate nontoxic metabolites upon degradation, which are easily eliminated from the body. The rate of water penetrating into the polyanhydride (PA) matrix is slower than the anhydride bond cleavage. This phenomenon sets PAs as "surface-eroding drug delivery carriers." Consequently, a variety of PA-based drug delivery carriers in the form of solid implants, pasty injectable formulations, microspheres, nanoparticles, etc. have been developed for the sustained release of small molecule drugs, and vaccines, peptide drugs, and nucleic acid-based active agents. The rate of drug delivery is often controlled by the polymer erosion rate, which is influenced by the polymer structure and composition, crystallinity, hydrophobicity, pH of the release medium, device size, configuration, etc. Owing to the above-mentioned interesting physicochemical and mechanical properties of PAs, the present review focuses on the advancements made in the domain of synthetic biodegradable biomedical PAs for therapeutic delivery applications. Various classes of PAs, their structures, their unique characteristics, their physicochemical and mechanical properties, and factors influencing surface erosion are discussed in detail. The review also summarizes various methods involved in the synthesis of PAs and their utility in the biomedical domain as drug, vaccine, and peptide delivery carriers in different formulations are reviewed.

Bioderived 4D Printable Terpene Photopolymers from Limonene and β-Myrcene

Green manufacturing and reducing our cultural dependency on petrochemicals have been topics of growing interest in the past decade, particularly for three-dimensional (3D) printable photopolymers where often toxic solvents and reagents have been required. Here, a simple solvent-free, free-radical polymerization is utilized to homo- and copolymerize limonene and β-myrcene monomers to produce oligomeric photopolymers (M_n < 11 kDa) displaying Newtonian, low viscosities (∼10 Pa × s) suitable for thiol-ene photo-cross-linking, yielding photoset materials in a digital light processing (DLP)-type 3D printer. The resulting photosets display tunable thermomechanical properties (poly(limonene) displays elastic moduli exceeding 1 GPa) compared with previous works focusing on monomeric terpenes as well as four-dimensional (4D) shape memory behavior. The utility of such photopolymers for biomedical applications is briefly considered on the premise of the hydrophilic nature (measured by contact angle) as well as their cytocompatibility upon seeding films with macrophages. These terpene-derived, green 4D photopolymers are shown to have promising physical behaviors suitable for an array of manufacturing and 3D printing applications.

Surface-Engineered Mucus Penetrating Nucleic Acid Delivery Systems with Cell Penetrating Peptides for the Lungs

Nucleic acids, both DNA and small RNAs, have emerged as potential therapeutics for the treatment of various lung disorders. However, delivery of nucleic acids to the lungs is challenging due to the barrier property imposed by mucus, which is further reinforced in disease conditions such as chronic obstructive pulmonary disease and asthma. The presence of negatively charged mucins imparts the electrostatic barrier property, and the mesh network structure of mucus provides steric hindrance to the delivery system. To overcome this, the delivery system either needs to be muco-inert with a low positive charge such that the interactions with mucus are minimized or should have the ability to transiently dismantle the mucus structure for effective penetration. We have developed a mucus penetrating system for the delivery of both small RNA and plasmid DNA independently. The nucleic acid core consists of a nucleic acid (pDNA/siRNA) and a cationic/amphipathic cell penetrating peptide. The mucus penetrating coating consists of the hydrophilic biopolymer chondroitin sulfate A (CS-A) conjugated with a mucolytic agent, mannitol. We hypothesize that the hydrophilic coating of CS-A would reduce the surface charge and decrease the interaction with negatively charged mucins, while the conjugated mannitol residues would disrupt the mucin-mucin interaction or decrease the viscosity of mucus by increasing the influx of water into the mucus. Our results indicate that CS-A-mannitol-coated nanocomplexes possess reduced surface charge, reduced viscosity of artificial mucus, and increased diffusion in mucin suspension as well as increased penetration through the artificial mucus layer as compared to the non-coated ones. Further, the coated nanocomplexes showed low cytotoxicity as well as higher transfection in A-549 and BEAS-2B cells as compared to the non-coated ones.

Exploring hydrophobic diastereomeric 2,6-anhydro-glycoheptitols for their enzymatic polymerization with PEG: towards delivery applications

Two sugar PEG-based amphiphilic copolymers have been synthesized by Novozym®-435-catalyzed greener solvent free transesterification reaction of diastereomeric 2,6-anhydro-glucoheptitol and 2,6-anhydro-mannoheptitol with PEG-1000 diethyl ester.

Vancomycin- and Poly(simvastatin)-Loaded Scaffolds with Time-Dependent Development of Porosity

Biodegradable scaffolds are widely use in drug delivery and tissue engineering applications. The scaffolds can be modified to provide the necessary mechanical support for tissue formation and to deliver one or more drugs to stimulate tissue formation or for the treatment of a specific condition. In the current study, we developed biodegradable scaffolds that have the potential for dual drug delivery. The scaffolds consisted of simvastatin-containing prodrug, poly(simvastatin) entrapped in poly(β-amino ester) (PBAE) porogen particles and vancomycin encapsulated in poly(lactic-co-glycolic acid) (PLGA) microspheres, which were fused together around the PBAE porogens to create a slow-degrading matrix. Upon hydrolysis, poly(simvastatin) releases simvastatin acid, which has angiogenic and osteogenic properties, while the PLGA microspheres release vancomycin as an antibacterial agent. Degradation of PBAE porogens through hydrolysis of ester linkages led to the development of porosity in a controlled manner and led to water penetration that facilitated hydrolysis of PLGA. Higher porogen loading (~60% by weight) gave rise to ~70% interconnected porosity with pore spacing of ~180 μm. This open volume facilitated simvastatin acid release upon hydrolysis and entrapped vancomycin release via diffusion through and degradation of PLGA. During the study, ~162 μg of simvastatin acid and ~18 mg vancomycin were released from the highest porosity scaffolds. Bioactivity studies showed that released simvastatin acid stimulated preosteoblastic activity, indicating that scaffold fabrication did not damage the polymeric prodrug. Regarding mechanical properties, compressive modulus, failure strain, and failure stress decreased with increasing PBAE porogen content. These dual drug releasing scaffolds with controlled development of microarchitecture can be useful in bone tissue engineering applications.

Biodegradable Simvastatin-Containing Polymeric Prodrugs with Improved Drug Release

Simvastatin was previously converted to a polymeric prodrug with higher drug loading, but the hydrophobic nature of the poly(simvastatin) component of the block copolymer led to slow release of the drug in vitro. In this study, we hypothesized that degradation could be accelerated by chemically modifying the polymer backbone by introducing glycolide and lactide comonomers. Copolymers were formed by ring-opening polymerization using 5 kDa monomethyl ether poly(ethylene glycol) as the microinitiator in presence of triazabicyclodecene catalyst. In addition to simvastatin, modified reaction mixtures contained lactide or glycolide. Incorporation of the less hydrophobic glycolide comonomer led to in vitro degradation of up to two times greater mass loss, release of up to ~7 times more simvastatin, and a 2-3 times increase in compressive modulus compared to the lactide-containing and parent polymers.

Amphiphilic block copolymer NPs obtained by coupling ricinoleic acid/sebacic acids and mPEG: Synthesis, characterization, and controlled release of paclitaxel

Currently, nanoparticles (NPs) made of amphiphilic block copolymer are still an essential part of drug delivery system. Here, we report a novel amphiphilic block copolymer and paclitaxel (PTX)-loaded copolymer NPs for the controlled delivery of PTX. The block copolymer was synthesized via melt polycondensation method of methoxy poly(ethylene glycol) (mPEG), sebacic acid (SA) and ricinoleic acid (RA). A series of characterization approaches such as Fourier Transform Infrared Spectroscopy (FTIR), ¹Hydrogen-Nuclear Magnetic Resonance (¹H-NMR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) and Gel Permeation Chromatography (GPC) applied have shown that the amphiphilic block copolymer was prepared as designed. NPs prepared by nanoprecipitation method consist of mPEG segments as the hydrophilic shell and RA-SA segments as the hydrophobic core, hydrophobic PTX was encapsulated as model drug. Subsequently, Transmission Electron Microscopy (TEM) analysis indicated that the spherical NPs have effective mean diameters ranging from 100 to 400 nm. Dynamic Light Scattering (DLS) analysis also revealed the controllable NPs diameter by modulating the mass ratio of RA to SA and drug loading amount (DLA). Besides, biphasic profile with zero order drug release was observed in general in vitro release behaviors of PTX from NPs. Further investigation confirmed that the release behaviors depend on the crystallinity of hydrophobic RA-SA segments. Results above suggest that NPs with amphiphlic block copolymer mPEG-b-P(RA-SA)-b-mPEG have a remarkable potential as a carrier for hydrophobic drug delivery in cancer therapy.

Recent Advances in Polyanhydride Based Biomaterials

This review focusses on recent developments of polyanhydrides, a class of degradable synthetic biopolymers. Polyanhydrides have been used as carriers for controlled delivery of drugs. A polyanhydride copolymer of carboxyphenoxy propane and sebacic acid has been used in Gliadel brain tumor implants for the controlled delivery of carmustine or bis-chloroethylnitrosourea. They are easy and inexpensive to synthesize (especially scale up). However, polyanhydrides possess a short shelf-life. Hydrolytic cleavage and anhydride interchanges lower their molecular weights during storage. One of the highlights in recent developments of polyanhydride chemistry is the discovery of alternating copolymers having extended shelf-life. Other highlights include their applications in biomedical electronics, vaccine delivery, and nano/micro particulate delivery systems. This review examines approaches for polyanhydride synthesis followed by their recent developments in biomedical applications.

A bio-based pro-antimicrobial polymer network via degradable acetal linkages

The synthesis of a fully degradable, bio-based, sustained release, pro-antimicrobial polymer network comprised of degradable acetals (PANDA) is reported. The active antimicrobial agent - p-anisaldehyde (pA) (an extract from star anise) - was converted into a UV curable acetal containing pro-antimicrobial monomer and subsequently photopolymerized into a homogenous thiol-ene network. Under neutral to acidic conditions (pH < 8), the PANDAs undergo surface erosion and exhibit sustained release of pA over 38 days. The release of pA from PANDAs was shown to be effective against both bacterial and fungal pathogens. From a combination of confocal microscopy and transmission electron microscopy, we observed that the released pA disrupts the cell membrane. Additionally, we demonstrated that PANDAs have minimal cytotoxicity towards both epithelial cells and macrophages. Although a model platform, these results point to promising pathways for the design of fully degradable sustained-release antimicrobial systems with potential applications in agriculture, pharmaceuticals, cosmetics, household/personal care, and food industries.

STATEMENT OF SIGNIFICANCE

With the increasing number of patients prescribed immunosuppressants coupled with the rise in antibiotic resistance - life-threatening microbial infections are a looming global threat. With limited success within the antibiotic pipeline, nature-based essential oils (EOs) are being investigated for their multimodal effectiveness against microbes. Despite the promising potential of EOs, difficulties in their encapsulation, limited water solubility, and high volatility limit their use. Various studies have shown that covalent attachment of these EO derivatives to polymers can mitigate these limitations. The current study presents the synthesis of a fully-degradable, sustained release, cytocompatible, pro-antimicrobial acetal network derived from p-anisaldehyde. This polymer network design provides a pathway toward application-specific EO releasing materials with quantitative encapsulation efficiencies, sustained release, and broad-spectrum antimicrobial activity.

One-pot preparation of polylactic acid-ibuprofen conjugates and their performance characterization

Merging esterification modification, carrier preparation, and chemical conjugation into a one-pot reaction as a new strategy for developing the polylactic acid-ibuprofen conjugates is described.

pH-Responsive nanoparticles based on ibuprofen prodrug as drug carriers for inhibition of primary tumor growth and metastasis

Cancer metastases represent a major determinant of mortality in patients with cancer.