Biodegradable Polyurethane Foam Research Articles

Biodegradable Polyurethane Foams Based on Polyols Obtained from Cellulose and Its Hydroxypropyl Derivative

Three methods of cellulose-derived polyol synthesis were elaborated. The suitable substrates were (hydroxypropyl)cellulose or cellulose, which were hydroxyalkylated in reactions with glycidol and ethylene carbonate in triethylene glycol or in water. The products were characterized by IR, 1H NMR, and MALDI ToF spectroscopies. For all polyols, IR spectra showed strong bands at 1060 cm−1 from the ether group formed upon the ring opening of GL and EC. The polyol obtained from (hydroxypropyl)cellulose in the triethylene glycol solvent was accompanied by oligomeric products of glycol hydroxyalkylation and oligomeric glycidol. The polyol obtained by the hydroxyalkylation of cellulose with glycidol and ethylene carbonate in the water contained units of hydroxyalkylated cellulose and products of hydroxyalkylation of water. The physical properties of the obtained polyols, like density, viscosity, and surface tension, were determined. The polyols were then used to obtain rigid polyurethane foams. The foams have apparent density, water uptake, and polymerization shrinkage similar to classic rigid PUFs. The foams showed advantageous thermal resistance in comparison with classic ones. After thermal exposure, their compressive strength improved. The biodegradation of the obtained materials was tested by a respirometric method in standard soil conditions by the measurement of biological oxygen demand and also using the cellulases or the enzymes responsible for cellulose degradation. It has been found that polyols are totally biodegradable within one month of exposure, while the foams obtained thereof are at least 50% biodegraded in the same conditions. The enzymatic biodegradation of the PUFs by the action of microbial cellulase was confirmed.

Evaluation of sodium hyaluronate-based composite hydrogels for prevention of nasal adhesions.

During the healing process after intra-nasal surgery, the growth and repair of damaged tissues can result in the development of postoperative adhesions. Various techniques have been devised to minimize the occurrence of postoperative adhesions which include insertion of stents in the middle meatus, application of removable nasal packing, and utilizing biodegradable materials with antiadhesive properties. This study assesses the efficacy of two sodium hyaluronate (SH)-based freeze-dried hydrogel composites in preventing postoperative nasal adhesions, comparing them with commonly used biodegradable materials in nasal surgery. The freeze-dried hydrogels, sodium hyaluronate and collagen 1(SH-COL1) and sodium hyaluronate, carboxymethyl cellulose, and collagen 1 (SH-CMC-COL1), were evaluated for their ability to reduce bleeding time, promote wound healing, and minimize fibrous tissue formation. Results showed that SH-CMC-COL1 significantly reduced bleeding time compared to both biodegradable polyurethane foam and SH-COL1. Both SH-COL1 and SH-CMC-COL1 exhibited enhanced wound healing effects, as indicated by significantly greater wound size reduction after two weeks compared to the control. Histological analyses revealed significant differences in re-epithelialization and blood vessel count among all tested materials, suggesting variable initial wound tissue response. Although all treatment groups had more epithelial growth, with X-SCC having higher blood vessel count at 7 d post treatment, all treatment groups did not differ in all histomorphometric parameters by day 14. However, the long-term application of SH-COL1 demonstrated a notable advantage in reducing nasal adhesion formation compared to all other tested materials. This indicates the potential of SH-based hydrogels, particularly SH-COL1, in mitigating postoperative complications associated with nasal surgery. These findings underscore the versatility and efficacy of SH-based freeze-dried hydrogel composites for the management of short-term and long-term nasal bleeding with an anti-adhesion effect. Further research is warranted to optimize their clinical use, particularly in understanding the inflammatory factors influencing tissue adhesions and assessing material performance under conditions mimicking clinical settings. Such insights will be crucial for refining therapeutic approaches and optimizing biomaterial design, ultimately improving patient outcomes in nasal surgery.

Outcomes of Biodegradable Temporizing Matrix for Soft Tissue Reconstruction of the Hand and Extremities.

NovoSorb biodegradable temporizing matrix (BTM) is a novel, bilayer, synthetic skin substitute made of biodegradable polyurethane foam covered with a sealing membrane. BTM has demonstrated excellent outcomes in burn literature; however, few studies have been published for hand and extremity soft tissue reconstruction. All patients who underwent extremity reconstruction with BTM from 2018 to 2023 were reviewed. Demographics, presentations, and clinical outcomes were recorded. A total of 86 cases from 54 patients (53.7% pediatric; age range: 0-81 years) were included. Common indications included trauma (36%), infection (18.6%), and malignancy (11.6%). BTM was placed over exposed tendon (38.4%), bone (19%), joints (12.8%), nerves (8.1%), and/or blood vessels (7%). BTM served as temporary wound coverage in 26 cases. Complications included hematoma (8.1%), infection (4.7%), and spontaneous delamination (4.7%). Wound closure was successfully obtained without flap use in 93.3%. Poor BTM take was associated with peripheral vascular disease, hypertension, immunosuppression, and BTM hematoma and infection (<0.05). This study contributes to the growing body of evidence favoring BTM use in challenging reconstructive cases. Although prospective comparative studies are forthcoming, BTM likely has broad applications in reconstructive surgery.

Cellulose-Based Polyurethane Foams of Low Flammability.

Decreasing oil resources creates the need to search for raw materials in the biosphere, which can be converted into polyols suitable for obtaining polyurethane foams (PUF). One such low-cost and reproducible biopolymer is cellulose. There are not many examples of cellulose-derived polyols due to the sluggish reactivity of cellulose itself. Recently, cellulose and its hydroxypropyl derivatives were applied as source materials to obtain polyols, further converted into biodegradable rigid polyurethane foams (PUFs). Those PUFs were flammable. Here, we describe our efforts to modify such PUFs in order to decrease their flammability. We obtained an ester from diethylene glycol and phosphoric(III) acid and used it as a reactive flame retardant in the synthesis of polyol-containing hydroxypropyl derivative of cellulose. The cellulose-based polyol was characterized by infrared spectra (IR) and proton nuclear magnetic resonance (1H-NMR) methods. Its properties, such as density, viscosity, surface tension, and hydroxyl numbers, were determined. Melamine was also added to the foamed composition as an additive flame retardant, obtaining PUFs, which were characterized by apparent density, water uptake, dimension stability, heat conductance, compressive strength, and heat resistance at 150 and 175 °C. Obtained rigid PUFs were tested for flammability by determining oxygen index, horizontal flammability test, and calorimetric analysis. Obtained rigid PUFs showed improved flammability resistance in comparison with non-modified PUFs and classic PUFs.

Renewable and Biodegradable Polyurethane Foams with Aliphatic Diisocyanates

Renewable and Biodegradable Polyurethane Foams with Aliphatic Diisocyanates

Comparison of Outcomes After Septoplasty With Non-Absorbable or Biodegradable Synthetic Polyurethane Foam Nasal Packing With a Focus on Pain and Cardiac Factors

Background and Objectives: We compared pain levels, cardiovascular parameters, and complications according to whether patients underwent nasal packing with non-absorbable or biodegradable materials.Methods: Patients who underwent septoplasty from May 2015 to April 2020 were retrospectively reviewed. Numeric rating scale (NRS) scores for pain, blood pressure, and heart rate were measured three times (immediately after surgery, 6 hours later, and on postoperative day [POD] 1). We collected data on complications, including postoperative bleeding, septal hematoma, adhesions, septal perforation, and the recurrence of septal deviation.Results: In total, 200 patients underwent septoplasty, of whom 100 underwent nasal packing with Merocel and 100 underwent packing with Nasopore. The summed NRS scores over the three time points did not differ significantly between the groups. The NRS scores at 6 hours after surgery were highest in both groups. The systolic and diastolic blood pressure and the heart rate immediately after surgery were significantly higher than before surgery in both groups. The blood pressure and heart rate at 6 hours after surgery and on POD 1 did not differ significantly from those before surgery in either group. The incidence of sleep disturbance, postoperative bleeding, septal hematoma, adhesions, septal perforation, and recurrence of septal deviation did not differ significantly between the two groups.Conclusion: Although the level of postoperative pain and the cardiovascular parameters changed over time, we found no significant differences in pain, blood pressure, heart rate, or the complication rate according to whether patients underwent nasal packing with Nasopore or Merocel.

Surgiflo® hemostatic matrix versus NasoPore® nasal packing following postassium titanyl phosphate laser surgery for hereditary hemorrhagic telangiectasia: A randomized controlled trial.

To help ensure adequate hemostasis immediately following potassium titanyl phosphate (KTP) laser treatment, many centres treating hereditary hemorrhagic telangiectasia (HHT) routinely use nasal packing post-operatively. The purpose of this study was to compare hemostatic thrombin matrix with standard packing for postoperative bleeding, patient pain, and comfort. A prospective, randomized, double-blinded, non-inferiority study was conducted with participants at an HHT centre of excellence (COE) and randomized to the treatment group with reconstituted thrombin gelatin matrix (Surgiflo®) or control group with a biodegradable synthetic polyurethane foam (NasoPore®). Adult subjects with confirmed HHT and moderate to severe epistaxis (a minimum calculated epistaxis severity score [ESS] of 4.0) warranting KTP laser treatment were recruited. Data was collected 2 weeks post operatively by a blinded reviewer completing a visual outcomes evaluation and each patient completing a subjective symptoms questionnaire. Non-parametric statistical analysis was employed. Twenty-eight adult patients were randomized to the treatment and control arms with comparable preoperative epistaxis severity scores. Postoperative nasal bleeding was equivalent. Significantly less pain was found in the treatment arm (p=.005). While there were trends towards less obstruction and increased satisfaction in the treatment group as well as less crusting in the control group, these findings were not statistically significant. Allocation to the treatment group was associated with an approximately $75 higher cost. When compared to NasoPore® for hemostasis, Surgiflo® hemostatic matrix performed equivalently while causing less discomfort in HHT patients following nasal KTP treatment. 1b.

Comparison of biopolymer scaffolds for the fabrication of skin substitutes in a porcine wound model.

This study compared three acellular scaffolds as templates for the fabrication of skin substitutes. A collagen-glycosaminoglycan (C-GAG), a biodegradable polyurethane foam (PUR) and a hybrid combination (PUR/C-GAG) were investigated. Scaffolds were prepared for cell inoculation. Fibroblasts and keratinocytes were serially inoculated onto the scaffolds and co-cultured for 14 days before transplantation. Three pigs each received four full-thickness 8cm × 8cm surgical wounds, into which a biodegradable temporising matrix (BTM) was implanted. Surface seals were removed after integration (28 days), and three laboratory-generated skin analogues and a control split-thickness skin graft (STSG) were applied for 16 weeks. Punch biopsies confirmed engraftment and re-epithelialisation. Biophysical wound parameters were also measured and analysed. All wounds showed greater than 80% epithelialisation by day 14 post-transplantation. The control STSG displayed 44% contraction over the 16 weeks, and the test scaffolds, C-GAG 64%, Hybrid 66.7% and PUR 67.8%. Immunohistochemistry confirmed positive epidermal keratins and basement membrane components (Integrin alpha-6, collagens IV and VII). Collagen deposition and fibre organisation indicated the degree of fibrosis and scar produced for each graft. All scaffold substitutes re-epithelialised by 4 weeks. The percentage of original wound area for the Hybrid and PUR was significantly different than the STSG and C-GAG, indicating the importance of scaffold retainment within the first 3 months post-transplant. The PUR/C-GAG scaffolds reduced the polymer pore size, assisting cell retention and reducing the contraction of in vitro collagen. Further investigation is required to ensure reproducibility and scale-up feasibility.

Chemometric Evaluation of a Biodegradable Tannic Acid-Polyurethane System for the Removal of Pb(II) and Hg(II) Ions from Water

The industrialization has brought advances that have enabled a better quality of life for people and improved production stages and business models. However, some impacts still need to be resolved, such as water pollution. Industrial pollutants containing potentially toxic metal ions are expensive for the industry, so studying new materials and new processes has helped solve this problem. Adsorption processes using biodegradable adsorbent materials have been presented as relevant alternatives for reusing metallic ions from water bodies and sewage networks. In this perspective, tannic acid (TA) immobilization in biodegradable polyurethane (PU) foams based on vegetable oil (castor oil) was used to remove metal ions Hg (II) and Pb (II) from water. The preliminary study was carried out in TA's immobilization in PUs, with a 2k order factorial experimental design. The responses were obtained and evaluated by gravimetry and UV-Vis spectroscopy using Central Composite Design (CCD). The molar concentration of 0.1000 mol L-1 by TA solution at pH equal to 7 and 19 hours of contact time was defined as optimal conditions for TA adsorption in the PU. The optimized PU-TA system was evaluated for removing Pb (II) and Hg (II) ions in aqueous solutions, and the tests showed that 59.93% and 51.48% were removed from water, respectively. The use of the PU-TA adsorbent system for removing metals in water can be widely valuable in industrial plants that need water treatment.

724 Role of synthetic dermal matrix for reconstruction of complex non-graftable wound defects

IntroductionThe aim of this study was to investigate the role of a synthetic dermal matrix, Biodegradable Temporising Matrix (BTM), for coverage of complex wounds. The authors defined complex wounds as wounds not amenable to reconstruction with skin grafting alone due to an inherent avascularity of the wound bed, such as the presence of exposed bone, tendinous or neural structures.MethodsA retrospective review of a prospectively maintained database of complex wounds as defined above was carried out. Clinical and operative notes were reviewed along with review of an extensive photographic database demonstrating wound healing progress using staged dermal matrix (BTM) and autologous skin graft reconstruction.Results55 patients were identified who underwent staged dermal matrix and autologous skin graft reconstruction for complex wounds affecting a wide variety of patient demographics, treatment indications and body sites. Wound aetiology varied between burn injury, non-burn related trauma including degloving injury and infective complications. We discuss caveats relating to successful application of a dermal matrix, technique tips, prevention and management of complications.Dermal substitutes play an integral role in providing biological wound cover for avascular wound beds which may otherwise require complex distant flap or microsurgical free flap reconstruction. BTM is a completely synthetic dermal matrix comprised of a 2-mm-thick sheet of biodegradable polyurethane foam bonded to a non-biodegradable polyurethane sealing membrane. Our department has developed significant expertise in the use of BTM throughout its development from initial animal studies through to recent human clinical trials. The synthetic composition of BTM does not require rapid neo-vascularisation for its integrity or survival. As such, two-stage BTM reconstruction has proven robustness in the face of unfavourable wounds compared with other popular dermal matrices, physiologically covering avascular structures, allowing for early graft take, expediting rehabilitation and mobilisation with excellent scar cosmesis and limited contracture formation.ConclusionsDermal matrices such as BTM play an important role in complex wound healing, frequently achieving excellent results with a low complication profile. BTM has been used successfully in cases where biological matrices would not routinely be considered as demonstrated by this clinical series. It has provided a valuable alternative to free-tissue transfer in patients with significant co-morbidities, vascular insufficiency and/or those for whom long operations are undesirable.

Bioabsorbable dressing impregnated with betamethasone and ciprofloxacin after endoscopic sinus surgery: A randomized, double-blind, placebo-controlled study.

In addition to its hemostatic and stabilization role, biodegradable nasal packing can be used as a carrier for drugs after functional endoscopic sinus surgery (FESS). The aim of this study was to compare the influence of biodegradable synthetic polyurethane foam (NasoPore) soaked with ciprofloxacin, or betamethasone, or both to the same foam soaked with saline after FESS. 120 adults with chronic rhinosinusitis, with and without polyps, directed for bilateral full-house FESS were enrolled for the study. The patients were randomized and blinded into 3 groups, depending on the type of postoperative procedure applied. Thus, NasoPore soaked with antibiotic was provided to the first group; in the second group, the steroid was used; and the combination of both, in the third group. In each case, the aforementioned procedure was administered on one side of the nose, while NasoPore was soaked in saline on the other, at the end of the surgery, respectively. The patients were requested to complete a questionnaire during their postoperative visits at 2, 10, 30, 90, and 180 days, scoring the level of complaints on the VAS scale, separately for each side. The evaluation of the healing process was performed at each visit using rigid endoscopy and subsequently rated on numerical scales. Decreased mucosal edema and secretion; reduced Lund-Kennedy score; and favorable influences on facial pressure, nasal blockage, and smell were most evidently seen in the group receiving the antibioticsteroid combination. The application of biodegradable nasal packing with betamethasone and ciprofloxacin in sino-nasal surgery has positive effects not only on the healing process but also impacts patient's comfort. To optimize it, however, further research is needed.

Influence of biodegradable polyurethane foam on biocoenosis and sludge activity in reactors simulating low-load wastewater treatments

Hydrophilic and fully aliphatic polyurethane (PUR) foam exhibiting a highly open cellular structure was used as a biodegradable biofilm carrier that would serve simultaneously as a nutrient source. A one-month laboratory testing in a reactor simulating domestic wastewater treatment plants was conducted based on chemical and hydrobiological analyses as well as evaluation of microorganism development and enzymatic activity. It was found that PUR foam can successfully serve as a carrier for microorganisms and simultaneously can be biodegraded when the supply of nutrition is limited.

Synthesis and degradation of 3D biodegradable polyurethane foam scaffolds based on poly (propylene fumarate) and poly[(R)-3-hydroxybutyrate

Tissue degeneration due to diseases, accidents, and wars is a worldwide issue. One of the methods used by regenerative medicine (RM) to aid tissue repair is by using a biodegradable tissue engineering scaffold (TES). Different body tissues have variable regeneration abilities, and hence, they require TES with variable degradation rates. This paper focuses on synthesising four polyurethane foam scaffolds (PUFS) with variable degradation rates based on the concentration of incorporated chain extender (CE) poly[(R)-3-hydroxybutyrate] (P3HB). The polyol employed is poly (propylene fumarate) (PPF) along with aliphatic 1,6-hexamethylene diisocyanate (HDI). GPC provided the molecular weight (Mn = 455.67 g mol−1, Mw = 587.15 g mol−1) and PDI (1.29) of the PPF. FTIR and 1H and 13C NMR confirmed the proposed structures (CC, COOR, and NHCOO) of the PUFS. The FESEM images revealed a bimodal pore structure, with random, irregular, interconnected pores (242–340 µm) and discrete void spaces (735–860 µm). The size of PUFS pores and void spaces (PU4 > PU3 > PU2 > PU1) is directly proportional to their respective degradation rates. The TGA/DTA curves show a decrease of an onset thermal decomposition temperature from PU1 to PU4 (267.17 ºC PU1, 267.28 ºC PU2, 256.01 ºC PU3 and 240.72 ºC PU4) due to the respective increase in CE concentration. The results of in-vitro degradation analysis at day 70, revealed significant difference between the weight loss (%) of each group (PU1 = 4.09 ± 0.18%, PU2 = 8.03 ± 0.17%, PU3 = 13.14 ± 0.12% and PU4 = 20.21 ± 0.19%). Thus, PUFS with a higher concentration of P3HB have a faster degradation rate due to the associated P3HB hydrolysable ester/-COOR functional group within the PUFS backbone. The chemical structure, bimodal morphology, and variable degradation rate of these PUFS could be employed for various RM applications.

The biodegradable cellulose-derived polyol and polyurethane foam

The method of polyol synthesis from cellulose, glycidol, and ethylene carbonate in water was elaborated. The obtained polyol was characterized by IR, 1H NMR and MALDI ToF spectroscopy. The polyol was then used to obtain rigid polyurethane foam. That foam have apparent density, water uptake, and polymerization shrinkage similar to conventional rigid polyurethane foams. The foam showed advantageous thermal resistance in comparison with classic ones. After thermal exposure its compressive strength was improved. The polyol is totally biodegradable in soil. The polyurethane foam obtained from this polyol was 70–80% biodegraded in soil within 28 days.

Fabrication of Biodegradable Polyurethane Foam Scaffolds with Customized Shapes and Controlled Mechanical Properties by Gas Foaming Technique

AbstractPoly(ε‐caprolactone) (PCL)‐based polyurethane (PU) foam scaffolds with different mechanical properties are fabricated using a gas foaming technique to use as porous substitutes for ear or bone with cartilage. PCL diol or triol is used as a polyol in PU foam for biocompatibility and biodegradation, with an aqueous gelatin solution as a blowing agent. The highly porous inner and outer structures of the scaffolds are developed by employing a silicone surfactant and sulfuric acid, respectively. The PU scaffolds prepared by PCL diol show ductile and flexible properties, whereas the PU scaffolds prepared by PCL triol exhibit high compression strength. In vitro test reveals the low toxicity of the PU scaffolds and the high ALP activity of MC3T3‐E1 cells in the PU scaffold prepared by PCL triol. By taking advantage of the difference in mechanical properties, customized PU scaffolds with ear or bone shapes are fabricated using a silicone mold. The PU scaffolds with two compartments of PCL diol and triol (corresponding to cartilage and bone, respectively) are fabricated as a substitute for bone with cartilage. It is believed that the PU scaffolds with highly porous structure and controlled mechanical properties have wide potential application for tissue engineering.

Scale-up of a Composite Cultured Skin Using a Novel Bioreactor Device in a Porcine Wound Model.

Extensive deep-burn management with a two-stage strategy can reduce reliance on skin autografts; a biodegradable polyurethane scaffold to actively temporize the wound and later an autologous composite cultured skin (CCS) for definitive closure. The materials fulfilling each stage have undergone in vitro and in vivo pretesting in "small" large animal wounds. For humans, producing multiple, large CCSs requires a specialized bioreactor. This article reports a system used to close large porcine wounds. Three Large White pigs were used, each with two wounds (24.5 cm × 12 cm) into which biodegradable dermal scaffolds were implanted. A sample from discarded tissue allowed isolation/culture of autologous fibroblasts and keratinocytes. CCS production began by presoaking a 1-mm-thick biodegradable polyurethane foam in autologous plasma. In the bioreactor cassette, fibroblasts were seeded into the matrix with thrombin until established, followed by keratinocytes. The CCSs were applied onto integrated dermal scaffolds on day 35, alongside a sheet skin graft (30% of one wound). Serial punch biopsies, trans-epidermal water loss readings (TEWL), and wound measurements indicated epithelialization. During dermal scaffold integration, negligible wound contraction was observed (average 4.5%). After CCS transplantation, the control skin grafts were "taken" by day 11 when visible islands of epithelium were clinically observed on 2/3 CCSs. Closure was confirmed histologically, with complete epithelialization by day 63 post-CCS transplantation (CCS TEWL ~ normal skin average 11.9 g/m2h). Four of six wounds demonstrated closure with robust, stratified epithelium. Generating large pieces of CCS capable of healing large wounds is thus possible using a specialized designed bioreactor.

Is Nasal Packing Necessary After Endoscopic Dacryocystorhinostomy Without Stent and Mucosal Flaps Preservation?

This study aimed to evaluate the effect of nasal packing on the surgical success and postoperative complications of endoscopic dacryocystorhinostomy (EnDCR) without using stents and mucosal flaps. The retrospective study comprised of 75 eyes of 65 consecutive patients undergoing EnDCR with the biting and removing technique. The patients were assigned to 2 groups depending on whether the biodegradable synthetic polyurethane foam was used or not (the packing group, 34 eyes; the nonpacking group, 41 eyes). At least 6 months after the EnDCR, the postoperative outcomes including anatomical and functional successes, and the postoperative complications such as synechia, granuloma, and bleeding were compared between the packing and nonpacking groups. Synechia was lower in the packing group (23.5% versus 24.4%) but it was not statistically significant (P = 0.93). There were also no significant differences in the granuloma and bleeding complications between the 2 groups (respectively, P = 0.72, P = 0.08). The success rates of anatomical and functional reached 88% in the packing group compared with 82.9%, and 75.6% in the nonpacking group (respectively, P = 0.74, P = 0.76). The present study findings suggest that both groups have no superiorities over each other in the surgical outcomes after the EnDCR. However, further randomized studies are recommended before the generalization can be made.

Bio-Degradable Polyurethane Foams Produced by Liquefied Polyol from Wheat Straw Biomass.

In the present work, an abundant and unused residue (wheat straw) has been employed to synthesize a polyol as a substituent of castor oil in polyurethane foams. The liquefied product showed excellent properties for the proposed application. Castor oil was substituted with up to 50% wheat straw polyol in the formulation of polyurethane foams, which were prepared using two different isocyanates (methylene diphenyl diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI)). The evaluation of physical, mechanical, and thermal properties of the foams revealed that these materials can successfully be formed with up to 40% wheat straw polyols since all the results were improved. Moreover, at this polyol concentration, the morphology of the foams was presented as a compact and ordered structure. Following this trend, the foams showed excellent biodegradability at 30 days (5.60 and 7.31% for TDI and MDI foams, respectively) and 60 days (8.49 and 9.88% for TDI and MDI foams, respectively) in the soil media tests carried out. Thus, the materials prepared in this work can be proposed for agricultural applications such as use in plant nurseries.

Comparison of biodegradable synthetic polyurethane foam versus Gelfoam packing in cartilage graft myringoplasty procedures

ObjectiveTo compare cartilage graft rates and graft morphologies when biodegradable Synthetic Polyurethane Foam (BSPF) and Gelfoam are used to pack the EAC after cartilage graft myringoplasty. MethodsEighty-two patients with chronic perforations underwent endoscopic myringoplasty and were randomized to receive Gelfoam or BSPF packing of the middle ear and EAC.The groups were compared with respect to the pre- and postoperative air-bone gap (ABG), graft integrity, graft epithelialization, graft lateralization, and exudate. ResultsGraft success rate was 87.8% in postoperative 3rd month and 87.8% in postoperative 12th month in the Gelfoam group, whereas graft success rate was 97.6% in postoperative 3rd month and 95.1% in postoperative 12th month in the BSPF group, with no statistical significance between two groups in the 3rd (P = 0.089) and 12th (P = 0.236) month after surgery. Comparing the two groups, there was no difference in preoperative or postoperative mean ABG and ABG closure. Graft lateralization or medialization was evident in 6 patients in the Gelfoam group and one in the BSPF group. Re-peroration occured in one patient in the BSPF group. ConclusionsAlthough cartilage graft myringoplasty between Gelfoam packing and BSPF packing of EAC achieve similar graft success rate and ABG closure, BSPF packing afford better graft support and less exudation than did Gelfoam, well prevent graft lateralization and promote earlier graft epithelialization.

Multifunctional and fully aliphatic biodegradable polyurethane foam as porous biomass carrier for biofiltration

Water-blown fully aliphatic polyurethane foam was prepared at room temperature from trimer of hexamethylene diisocyanate and poly(diethylene glycol adipate) diol and post cured at 55 °C. In contrast to aromatic-based PUR foam analog, the produced flexible PUR foam exhibited highly porous structure with open cell content of 94% and average cell size of 700 μm. Therefore, it was subsequently tested as biodegradable cellular carrier of microorganisms (fungus Fusarium solani and bacterium Pseudomonas sp.) for biofiltration. Firstly, tests on enzyme activities (lipase, protease and urease) and utilization of PUR foam as the sole carbon and nitrogen source and determination of degradation products were carried out. Fusarium solani shown much higher both enzyme and degradation activities and higher spectrum of degradation products. Finally, the performance of a biofilter packed with the developed cellular carrier was investigated for removal of a mixture of acetone, propionic acid, ethyl acetate, toluene and α-pinene. Proven sorption properties of PUR foam against all pollutants and a high maximum elimination capacity of 218 ± 33 g m−3 h−1 make the new lightweight biofilm PU carrier suitable for this application due to their multi-functionality.