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Molecules (Basel, Switzerland) Jun 2024This study presents fibers based on methacrylic acid-methyl methacrylate (Eudragit L100) as Cu(II) adsorbents, resulting in antimicrobial complexes. Eudragit L100, an...
This study presents fibers based on methacrylic acid-methyl methacrylate (Eudragit L100) as Cu(II) adsorbents, resulting in antimicrobial complexes. Eudragit L100, an anionic copolymer synthesized by radical polymerization, was electrospun in dimethylformamide (DMF) and ethanol (EtOH). The electrospinning process was optimized through a 2-factorial design, with independent variables (copolymer concentration and EtOH/DMF volume ratio) and three repetitions at the central point. The smallest average fiber diameter (259 ± 53 nm) was obtained at 14% / Eudragit L100 and 80/20 EtOH/DMF volume ratio. The fibers were characterized using scanning electron microscopy (SEM), infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), and differential scanning calorimetry (DSC). The pseudo-second-order mechanism explained the kinetic adsorption toward Cu(II). The fibers exhibited a maximum adsorption capacity (q) of 43.70 mg/g. The DSC analysis confirmed the Cu(II) absorption, indicating complexation between metallic ions and copolymer networks. The complexed fibers showed a lower degree of swelling than the non-complexed fibers. The complexed fibers exhibited bacteriostatic activity against Gram-negative () and Gram-positive () bacteria. This study successfully optimized the electrospinning process to produce thin fibers based on Eudragit L100 for potential applications as adsorbents for Cu(II) ions in aqueous media and for controlling bacterial growth.
Topics: Copper; Polymethacrylic Acids; Anti-Infective Agents; Adsorption; Spectroscopy, Fourier Transform Infrared; Staphylococcus aureus; Methacrylates; Kinetics; Calorimetry, Differential Scanning; Microbial Sensitivity Tests
PubMed: 38930901
DOI: 10.3390/molecules29122835 -
Medicina (Kaunas, Lithuania) May 2024: Proximal junctional kyphosis (PJK) and failure (PJF), the most prevalent complications following long-segment thoracolumbar fusions for adult spinal deformity (ASD),...
Can We Rely on Prophylactic Two-Level Vertebral Cement Augmentation in Long-Segment Adult Spinal Deformity Surgery to Reduce the Incidence of Proximal Junctional Complications?
: Proximal junctional kyphosis (PJK) and failure (PJF), the most prevalent complications following long-segment thoracolumbar fusions for adult spinal deformity (ASD), remain lacking in defined preventive measures. We studied whether one of the previously reported strategies with successful results-a prophylactic augmentation of the uppermost instrumented vertebra (UIV) and supra-adjacent vertebra to the UIV (UIV + 1) with polymethylmethacrylate (PMMA)-could also serve as a preventive measure of PJK/PJF in minimally invasive surgery (MIS). : The study included 29 ASD patients who underwent a combination of minimally invasive lateral lumbar interbody fusion (MIS-LLIF) at L1-2 through L4-5, all-pedicle-screw instrumentation from the lower thoracic spine to the sacrum, S2-alar-iliac fixation, and two-level balloon-assisted PMMA vertebroplasty at the UIV and UIV + 1. : With a minimum 3-year follow-up, non-PJK/PJF group accounted for fifteen patients (52%), PJK for eight patients (28%), and PJF requiring surgical revision for six patients (21%). We had a total of seven patients with proximal junctional fracture, even though no patients showed implant/bone interface failure with screw pullout, probably through the effect of PMMA. In contrast to the PJK cohort, six PJF patients all had varying degrees of neurologic deficits from modified Frankel grade C to D3, which recovered to grades D3 and to grade D2 in three patients each, after a revision operation of proximal extension of instrumented fusion with or without neural decompression. None of the possible demographic and radiologic risk factors showed statistical differences between the non-PJK/PJF, PJK, and PJF groups. : Compared with the traditional open surgical approach used in the previous studies with a positive result for the prophylactic two-level cement augmentation, the MIS procedures with substantial benefits to patients in terms of less access-related morbidity and less blood loss also provide a greater segmental stability, which, however, may have a negative effect on the development of PJK/PJF.
Topics: Humans; Female; Male; Middle Aged; Bone Cements; Aged; Kyphosis; Spinal Fusion; Postoperative Complications; Lumbar Vertebrae; Thoracic Vertebrae; Incidence; Adult; Minimally Invasive Surgical Procedures; Polymethyl Methacrylate; Vertebroplasty; Retrospective Studies; Treatment Outcome
PubMed: 38929477
DOI: 10.3390/medicina60060860 -
The Iowa Orthopaedic Journal 2024The specific aim of this study was to evaluate the mechanical properties of cement prepared with the advanced one-step mixing system and whether the addition of vacuum...
BACKGROUND
The specific aim of this study was to evaluate the mechanical properties of cement prepared with the advanced one-step mixing system and whether the addition of vacuum conditions yielded an appreciable improvement in the biomechanical strength or overall quality of bone cement.
METHODS
The advanced one-step mixing system was used. Twelve specimens were prepared by mixing under vacuum conditions and 12 specimens were prepared by mixing without a vacuum. Radiographs of cement specimens were analyzed to determine the porosity of the test region. Tensile testing of the specimens was performed with a loading rate of 2.54mm/min at room temperature. The ultimate tensile strength (UTS) and the tensile elastic modulus (E) were determined for each sample.
RESULTS
The UTS of the bone cement samples mixed under vacuum conditions were not significantly different than those mixed without vacuum (vacuum: 39±6MPa; non-vacuum: 35±6MPa; p=0.637). The E of samples mixed under vacuum conditions was significantly higher than the bone cement mixed without vacuum (vacuum: 2.78±0.06GPa; non-vacuum: 2.63±0.15GPa; p=0.019). Radiographic images showed samples mixed under vacuum conditions contained fewer defects than the samples mixed without vacuum (vacuum: 3.5%±3.3% (range: 0.0%-9.0%); non-vacuum: 6.9%±1.0% (range: 4.6%-8.2%)).
CONCLUSION
Mixing bone cement with the advanced one-step mixing system under vacuum conditions does not produce an appreciable difference in the UTS of the bone cement in a bench biomechanical testing model compared to the bone cement mixed without vacuum. It does, however, create a less porous cement mixture with a higher E compared to cement mixed without vacuum. .
Topics: Vacuum; Materials Testing; Tensile Strength; Bone Cements; Polymethyl Methacrylate; Humans; Elastic Modulus; Biomechanical Phenomena; Porosity
PubMed: 38919359
DOI: No ID Found -
The International Journal of... Jun 2024To analyze the effect of disinfectants on the roughness and mechanical properties of CAD/ CAM polymethylmethacrylate (PMMA) dentures.
PURPOSE
To analyze the effect of disinfectants on the roughness and mechanical properties of CAD/ CAM polymethylmethacrylate (PMMA) dentures.
MATERIALS AND METHODS
Two groups of denture base resins were tested-heat-polymerized and milled blocks. For each resin, 120 specimens were produced for flexural strength (FS) and flexural modulus (FM) analyses (total: 240 specimens), and 40 were produced for microhardness and surface roughness evaluations (total: 80 specimens). They were categorized into the following groups based on immersion: control (deionized water); H1 (1% sodium hypochlorite); H05 (0.5% sodium hypochlorite); and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using threeway ANOVA. Microhardness (KHN) and surface roughness (Ra) were analyzed using repeated-measures ANOVA. A significance level of 5% was set.
RESULTS
CAD/CAM PMMA showed higher FS (P = .001) and FM (P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA (P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/ CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs baseline; P < .05).
CONCLUSIONS
The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable.
Topics: Polymethyl Methacrylate; Surface Properties; Computer-Aided Design; Materials Testing; Flexural Strength; Hardness; Denture Bases; Disinfection; Chlorhexidine; Sodium Hypochlorite
PubMed: 38905586
DOI: 10.11607/ijp.8301 -
Indian Journal of Ophthalmology Jul 2024The aim of this study is to describe a modified technique for internal refixation of dislocated scleral-sutured polymethylmethacrylate (PMMA) intraocular lenses (IOLs)...
The aim of this study is to describe a modified technique for internal refixation of dislocated scleral-sutured polymethylmethacrylate (PMMA) intraocular lenses (IOLs) with eyelets. Three-port pars plana vitrectomy was performed. Through the scleral fixation site, a 30-gauge needle loaded with an 8-0 polypropylene suture was inserted into the vitreous cavity. The suture end was passed through the eyelet of IOL with 25-gauge forceps. Next, it was guided out of the eye through the original scleral fixation point. The end of the exterior suture was buried with a flapless intrascleral knotting technique. Six eyes of six patients were successfully treated with this technique and followed up for 6-12 months postsurgery. In all cases, there was significant improvement in uncorrected visual acuity. IOLs were stable with proper centration and no major complications. This modified technique offers an effective and minimally invasive surgical alternative for refixation of dislocated scleral-sutured PMMA IOLs with eyelets.
Topics: Humans; Polymethyl Methacrylate; Male; Visual Acuity; Lenses, Intraocular; Female; Reoperation; Suture Techniques; Vitrectomy; Middle Aged; Sclera; Artificial Lens Implant Migration; Follow-Up Studies; Aged; Sutures; Adult
PubMed: 38905465
DOI: 10.4103/IJO.IJO_2809_23 -
Frontiers in Veterinary Science 2024Even with recent research advances, effective delivery of a compound to its target cells inside the inner ear remains a challenging endeavor due to anatomical and...
INTRODUCTION
Even with recent research advances, effective delivery of a compound to its target cells inside the inner ear remains a challenging endeavor due to anatomical and physiological barriers. Direct intracochlear drug administration with an inner ear catheter (IEC) aims to overcome this obstacle and strives to provide a safe and efficient way for inner ear pharmacotherapy. The goal of this study was to histologically and audiologically evaluate the traumatic properties of a novel IEC for intracochlear drug delivery in a large animal model.
METHODS
Seven inner ears of piglets that had undergone intracochlear fluorescein isothiocyanate dextran application via an IEC ( = 4) or round window membrane (RWM) puncture with a needle ( = 3) followed by sequential apical perilymph sampling were histologically analyzed. Additionally, obtained objective auditory compound action potential and cochlear microphonic measurements were compared. Cochlear cryosections were stained using hematoxylin and eosin, and preservation of inner ear structures was investigated. Moreover, one cochlea was methylmethacrylate-embedded and analyzed with the IEC .
RESULTS
Histological evaluation revealed an atraumatic insertion and subsequent compound application in a majority of IEC-inserted inner ears. Click cochlear compound action potential (CAP) shifts in the IEC groups reached a maximum of 5 dB (1.25 ± 2.5 dB) post administration and prior to perilymph sampling. In comparison, application by RWM puncture generated a maximum click CAP hearing threshold shift of 50 dB (23.3 ± 23.1 dB) coinciding with coagulated blood in the basal cochlear turn in one specimen of the latter group. Furthermore, histology showed an atraumatic insertion of the IEC demonstrating preserved intracochlear structures.
CONCLUSION
The IEC appears to be a promising and efficient way for inner ear drug delivery. The similarities between the porcine and human inner ear enhance the clinical translation of our findings and increase confidence regarding the safe applicability of the IEC in human subjects.
PubMed: 38903692
DOI: 10.3389/fvets.2024.1397554 -
Langmuir : the ACS Journal of Surfaces... Jun 2024Polymers are the most commonly used packaging materials for nutrition and consumer products. The ever-growing concern over pollution and potential environmental...
Polymers are the most commonly used packaging materials for nutrition and consumer products. The ever-growing concern over pollution and potential environmental contamination generated from single-use packaging materials has raised safety questions. Polymers used in these materials often contain impurities, including unreacted monomers and small oligomers. The characterization of transport properties, including diffusion and leaching of these molecules, is largely hampered by the long timescales involved in shelf life experiments. In this work, we employ atomistic molecular simulation techniques to explore the main mechanisms involved in the bulk and interfacial transport of monomer molecules from three polymers commonly employed as packaging materials: polyamide-6, polycarbonate, and poly(methyl methacrylate). Our simulations showed that both hopping and continuous diffusion play important roles in inbound monomer diffusion and that solvent-polymer compatibility significantly affects monomer leaching. These results provide rationalization for monomer leaching in model food formulations as well as bulky industry-relevant molecules. Through this molecular-scale characterization, we offer insights to aid in the design of polymer/consumer product interfaces with reduced risk of contamination and longer shelf life.
Topics: Food Packaging; Diffusion; Plastics; Molecular Dynamics Simulation; Polymethyl Methacrylate; Polycarboxylate Cement; Polymers; Food Contamination
PubMed: 38847174
DOI: 10.1021/acs.langmuir.4c00859 -
Injury Jul 2024As a two-stage surgical procedure, Masquelet's technique has been used to care for critical-size bone defects (CSD). We aimed to determine the effects of modified and...
BACKGROUND
As a two-stage surgical procedure, Masquelet's technique has been used to care for critical-size bone defects (CSD). We aimed to determine the effects of modified and altered bone cement with biological or chemical enriching agents on the progression of Masquelet's induced membrane (IM) applied to a rat femur CSD model, and to compare the histopathological, biochemical, and immunohistochemical findings of these cements to enhance IM capacity.
METHODS
Thirty-five male rats were included in five groups: plain polymethyl methacrylate (PMMA), estrogen-impregnated PMMA (E+PMMA), bone chip added PMMA (BC+PMMA), hydroxyapatite-coated PMMA (HA) and calcium phosphate cement (CPC). The levels of bone alkaline phosphatase (BALP), osteocalcin (OC), and tumor necrosis factor-alpha (TNF-α) were analyzed in intracardiac blood samples collected at the end of 4 weeks of the right femur CSD intervention. All IMs collected were fixed and prepared for histopathological scoring. The tissue levels of rat-specific Transforming Growth Factor-Beta (TGF-β), Runt-related Transcription Factor 2 (Runx2), and Vascular Endothelial Growth Factor (VEGF) were analyzed immunohistochemically.
RESULTS
Serum levels of BALP and OC were significantly higher in E+PMMA and BC+PMMA groups than those of other groups (P = 0.0061 and 0.0019, respectively). In contrast, TNF-α levels of all groups with alternative bone cement significantly decreased compared to bare PMMA (P = 0.0116). Histopathological scores of E+PMMA, BC+PMMA, and CPC groups were 6.86 ± 1.57, 4.71 ± 0.76, and 6.57 ± 1.51, respectively, which were considerably higher than those of PMMA and HA groups (3.14 ± 0.70 and 1.86 ± 0.69, respectively) (P < 0.0001). Significant increases in TGF-β and VEGF expressions were observed in E+PMMA and CPC groups (P = 0.0001 and <0.0001, respectively) whereas Runx2 expression significantly increased only in the HA group compared to other groups (P < 0.0001).
CONCLUSIONS
The modified PMMA with E and BC, and CPC as an alternative spacer resulted in a well-differentiated IM and increased IM progression by elevating BALP and OC levels in serum and by mediating expressions of TGF-β and VEGF at the tissue level. Estrogen-supplemented cement spacer has yielded promising findings between modified and alternative bone cement.
Topics: Animals; Bone Cements; Rats; Male; Polymethyl Methacrylate; Disease Models, Animal; Vascular Endothelial Growth Factor A; Femur; Femoral Fractures; Core Binding Factor Alpha 1 Subunit; Osteocalcin; Alkaline Phosphatase; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Rats, Sprague-Dawley; Calcium Phosphates; Fracture Healing; Bone Regeneration; Durapatite
PubMed: 38834011
DOI: 10.1016/j.injury.2024.111627 -
Journal of Materials Science. Materials... Jun 2024This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate...
AIM
This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate (MMA), crucial components in dental materials for interim prosthetic restorations.
METHODOLOGY
Molecular docking was employed to predict the binding affinities, energetics, and steric features of MMA and PMMA with selected receptors involved in bone metabolism and tissue development, including RANKL, Fibronectin, BMP9, NOTCH2, and other related receptors. The HADDOCK standalone version was utilized for docking calculations, employing a Lamarckian genetic algorithm to explore the conformational space of ligand-receptor interactions. Furthermore, molecular dynamics (MD) simulations over 100 nanoseconds were conducted using the GROMACS package to evaluate dynamic actions and structural stability. The LigandScout was utilized for pharmacophore modeling, which employs a shape-based screening approach to identify potential ligand binding sites on protein targets.
RESULTS
The molecular docking studies elucidated promising interactions between PMMA and MMA with key biomolecular targets relevant to dental applications. MD simulation results provided strong evidence supporting the structural stability of PMMA complexes over time. Pharmacophore modeling highlighted the significance of carbonyl and hydroxyl groups as pharmacophoric features, indicating compounds with favorable biocompatibility profiles.
CONCLUSION
This study underscores the potential of PMMA in dental applications, emphasizing its structural stability, molecular interactions, and safety considerations. These findings lay a foundation for future advancements in dental biomaterials, guiding the design and optimization of materials for enhanced biocompatibility. Future directions include experimental validation of computational findings and the development of PMMA-based dental materials with improved biocompatibility and clinical performance.
Topics: Molecular Docking Simulation; Biocompatible Materials; Molecular Dynamics Simulation; Polymethyl Methacrylate; Dental Materials; Materials Testing; Humans; Ligands; Computer Simulation; Binding Sites
PubMed: 38833196
DOI: 10.1007/s10856-024-06799-7 -
ACS Applied Bio Materials Jun 2024We investigated the possibility of loading PMMA bone cement with antimicrobial nanostructured AgNbO particles to counter biofilm formation at the cement-tissue...
We investigated the possibility of loading PMMA bone cement with antimicrobial nanostructured AgNbO particles to counter biofilm formation at the cement-tissue interface. We found that a formulation containing (1-4)% AgNbO showed high antibacterial activity against Gram-positive and Gram-negative while not showing any toxicity against THP1 human cell lines. In addition, loading the particles did not impact the mechanical properties of the cement. The results thus obtained illustrate the potential of the approach to replace the current technique of mixing cement with conventional antibiotics, which is associated with shortcomings such as efficacy loss from antibiotic depletion.
Topics: Bone Cements; Polymethyl Methacrylate; Anti-Bacterial Agents; Humans; Staphylococcus aureus; Pseudomonas aeruginosa; Microbial Sensitivity Tests; Materials Testing; Particle Size; Biocompatible Materials; Biofilms; Nanoparticles
PubMed: 38830835
DOI: 10.1021/acsabm.4c00373