Macromol, Volume 2, Issue 1 (March 2022) – 8 articles

In this work, two new water-soluble photoinitiators based on the α-alkoxy-arylketone scaffold have been synthesized and investigated for their ability to initiate photopolymerization for the preparation of hydrogels. The efficiency of these new Type I photoinitiators was compared to that of benchmark ones (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone—Irgacure 2959 and 2-hydroxy-2-methyl propiophenone—Irgacure 1173). In combination with additive (carbene-borane), a good initiating ability was found under air. Mechanical properties of the prepared hydrogels were investigated by tensile tests and dynamic mechanical analysis (DMA). Markedly, hydrogels could be prepared with the newly proposed initiating systems in mild conditions (i.e., under air, using low light intensity @405 or 395 nm and without specialized glassware) and exhibited similar properties to those prepared by harsher approaches (thermal treatment or UV light). Full article

As final attributes of dosage form largely depend on the properties of excipients used, understanding the effect of physicochemical properties of excipients is important. In the present study, six grades of L-HPC with varying degrees of particle size and hydroxypropyl content and the influence of the grade on compaction as well as disintegration behavior were studied. All grades of L-HPC were compressed at different compression loads to achieve different tablet porosity. Compressibility and compactibility of L-HPC grades were evaluated using a modified Heckel equation and percolation model. Further effects of particle size and hydroxypropyl content of L-HPC on tablet porosity and disintegration time were evaluated using a 3² full-factorial design. From compaction studies, it was found that compressibility of L-HPC largely depends upon the particle size with lower particle size grade showing lower compressibility. Whereas consolidation/bonding behavior of L-HPC is independent of particle size and % hydroxypropyl content. By factorial design, it was found that particle size and % hydroxypropyl content have a significant effect on the disintegration behavior of L-HPC. It was found that smaller particle sizes and higher hydroxypropyl content of L-HPC show longer disintegration time. Thus, careful consideration of excipients selection should be made to achieve desired quality attribute of the product. Full article

Arboviral diseases have a high incidence in Brazil and constitute a serious public health problem. Rocio virus (ROCV) is an arbovirus belonging to the family Flaviviridae. It was responsible for the emergence of an outbreak of encephalitis on the São Paulo state coast in the late 1970s. Although no recent case of this virus has been reported, data suggest the circulation of ROCV throughout the Brazilian territory. Given these indications and the strong presence of fundamental factors for the resurgence of emerging diseases in Brazil, we conducted this study using virtual screenings to identify targets and therapeutic molecules that could be redirected to fight infections related to ROCV. Herein, we demonstrated that the National List of Essential Medicines of the Brazilian Unified Health System (SUS) has several molecules that could be redirected to combat this flavivirus, namely simeprevir, daclatasvir, iloprost, and itraconazole. Among them, itraconazole was found to be an interesting candidate since it interacts with both structural and nonstructural proteins of this virus and it is a strong binder to the NS1 protein, as confirmed by molecular simulations. Full article

Conducting polymers, mainly polyaniline (PANI) and polypyrrole (PPY) with positive charges bind to the negatively charged bacterial membrane to interfere with bacterial activities. After this initial electrostatic adherence, the conducting polymers might partially penetrate the bacterial membrane and interact with other intracellular biomolecules. Conducting polymers can form polymer composites with metal, metal oxides, and nanoscale carbon materials as a new class of antimicrobial agents with enhanced antimicrobial properties. The accumulation of elevated oxygen reactive species (ROS) from composites of polymers-metal nanoparticles has harmful effects and induces cell death. Among such ROS, the hydroxyl radical with one unpaired electron in the structure is most effective as it can oxidize any bacterial biomolecules, leading to cell death. Future endeavors should focus on the combination of conducting polymers and their composites with antibiotics, small peptides, and natural molecules with antimicrobial properties. Such arsenals with low cytotoxicity are expected to eradicate the ESKAPE pathogens: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. Full article

In the present study, a series of aliphatic polyesters based on succinic acid and several diols with 2, 4, 6, 8, and 10 methylene groups, namely poly(ethylene succinate) (PESu), poly(butylene succinate) (PBSu), poly(hexylene succinate) (PHSu), poly(octylene succinate) (POSu), and poly(decylene succinate) (PDeSu), were prepared via a two-stage melt polycondensation method. All polyesters were semicrystalline materials with T_m ranging from 64.2 to 117.8 °C, while their T_g values were progressively decreasing by increasing the methylene group number in the used diols. Thermogravimetric analysis (TGA) revealed that the synthesized poly(alkylene succinate)s present high thermal stability with maximum decomposition rates at temperatures 420–430 °C. The thermal decomposition mechanism was also evaluated with the aid of Pyrolysis–Gas chromatography/Mass spectrometry (Py–GC/MS), proving that all the studied polyesters decompose via a similar pathway, with degradation taking place mainly via β–hydrogen bond scission and less extensive with homolytic scission. Full article

Given the fossil fuel crisis and the steady consumption of finite resources, the use of green polymers is becoming necessary. However, the term “green” describes materials that present green properties (such as biological origin and/or biodegradability) and are produced via sustainable processes conducted under mild conditions and not requiring the use of chemical catalysts, toxic solvents or reagents. Truly green materials must combine these characteristics; consequently, enzymatically synthesized bio-based and/or biodegradable polymers can be characterized as truly green. The present review focuses on the most promising, commercially available aliphatic and alipharomatic polyesters that can be synthesized enzymatically. In particular, the recent developments in the enzymatic polymerization of PLA and PBS and alipharomatic furan-based polyesters (e.g., PBF) are herein analyzed. Based on this analysis, it can be concluded that important steps have been taken toward synthesizing sustainably green polymers. Still, it is necessary to evaluate the applied methods regarding their capability to be used on an industrial scale. Full article

Additive manufacturing (AM), frequently cited as three-dimensional (3D) printing, is a relatively new manufacturing technique for biofabrication, also called 3D manufacture with biomaterials and cells. Recent advances in this field will facilitate further improvement of personalized healthcare solutions. In this regard, tailoring several healthcare products such as implants, prosthetics, and in vitro models, would have been extraordinarily arduous beyond these technologies. Three-dimensional-printed structures with a multiscale porosity are very interesting manufacturing processes in order to boost the capability of composite scaffolds to generate bone tissue. The use of biomimetic hydroxyapatite as the main active ingredient for bioinks is a helpful approach to obtain these advanced materials. Thus, 3D-printed biomimetic composite designs may produce supplementary biological and physical benefits. Three-dimensional bioprinting may turn to be a bright solution for regeneration of bone tissue as it enables a proper spatio-temporal organization of cells in scaffolds. Different types of bioprinting technologies and essential parameters which rule the applicability of bioinks are discussed in this review. Special focus is made on hydroxyapatite as an active ingredient for bioinks design. The goal of such bioinks is to reduce the constraints of commonly applied treatments by enhancing osteoinduction and osteoconduction, which seems to be exceptionally promising for bone regeneration. Full article

High-molecular-weight hypromellose (HPMC) and hydroxypropyl cellulose (HPC) are widely known, extended-release polymers. Conventional high-molecular-weight HPMCs are preferred in extended-release applications but not widely used in twin-screw melt granulation due to processability difficulties at low operating temperatures and potential drug degradation if high processing temperatures are used. Conversely, high-molecular-weight grade HPC (Klucel^®) can be used in melt granulation processes. The purpose of this study was to evaluate the processability and dissolution behavior of HPC GXF ((Klucel^® GXF) and a recently introduced type of hot-melt extrudable HPMC (Affinisol^®) in extended-release metformin hydrochloride formulations using twin-screw melt granulation. Powder blends were prepared with 75% w/w metformin HCl and 25% w/w polymeric binder. Blends were granulated at processing temperatures of 160, 140, 120 and 100 °C. HPMC HME 4M (Affinisol^® 4M) provided a fine powder, indicating minimum granulation at processing temperatures lower than 160 °C, and the tablets obtained with these granules capped during tableting. In contrast, acceptable tablets could be obtained with HPC GXF at all processing temperatures. Rheological studies including capillary rheometry to measure steady shear rate viscosity, and rotational rheometry to obtain time and temperature superposition data, showed that HPC GXF had a greater thermoplasticity than HPMC HME 4M, which made granulation possible with HPC GXF at low temperatures. Tablets compressed with granules obtained at 160 °C with both binders showed comparable dissolution profiles. High-molecular-weight HPC GXF provided a better processability at low temperatures and adequate tablet strength for the melt granulation of metformin HCl. Full article