Characterization of membranes based on cellulose acetate butyrate/poly(caprolactone)triol/doxycycline and their potential for guided bone regeneration application

Polymeric Membranes for Biomedical Applications

Polymeric membranes are selective materials used in a wide range of applications that require separation processes, from water filtration and purification to industrial separations. Because of these materials' remarkable properties, namely, selectivity, membranes are also used in a wide range of biomedical applications that require separations. Considering the fact that most organs (apart from the heart and brain) have separation processes associated with the physiological function (kidneys, lungs, intestines, stomach, etc.), technological solutions have been developed to replace the function of these organs with the help of polymer membranes. This review presents the main biomedical applications of polymer membranes, such as hemodialysis (for chronic kidney disease), membrane-based artificial oxygenators (for artificial lung), artificial liver, artificial pancreas, and membranes for osseointegration and drug delivery systems based on membranes.

Analysis of the biocompatibility of a biocelulose and a poly L- lactic acid membrane

The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim: The purpose of the present study was to evaluate the biocompatibility of poly (L- lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods: Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) – Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results: The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion: The PLLA and COL membranes present better biocompatibility than the BC membranes.

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

Alleviating neuropathy of diabetic foot ulcer by co-delivery of venlafaxine and matrix metalloproteinase drug-loaded cellulose nanofiber sheets: production, in vitro characterization and clinical trial

BACKGROUND

The objective of the present study was co-delivery of venlafaxin (VEN) and doxycycline (DOX), a matrix metalloproteinase inhibitor drug, for alleviating inflammation and neuropathy in diabetic foot ulcer (DFU).

METHODS

Bacterial cellulose nanofiber sheets (BCNS) were loaded with DOX and VEN and categorized by their loading efficiency, release profiles and ex vivo permeation throughrat skin. The optimized nanofibers were used in patients with DFU to compare with the standard wound care regimen during a 12-week trial. Wound area was measured every 2 weeks. Biochemical parameters and microscopic studies of the skin were examined prior and at the end of the treatment. The Michigan Neuropathy Screening Instrument (MNSI) questionnaire was utilized to assess diabetic neuropathy.

RESULTS

The optimum formulation showed loading efficiency of 37.8 ± 1.6% for DOX and 48 ± 1.9% for VEN. Rat skin permeation was 40% for DOX after 7-29 h and 83% for VEN during 105 h. Patients treated with BCNS showed no significant difference in their biochemical parameters before and after intervention. The ulcer size showed faster reduction after 12 weeks in the treatment group compared to the control group. The abnormal responses in the MNSI questionnaire decreased and pain-free walking distance increased significantly in the treatment group compared with the control group (p < 0.001). Microscopic studies of the skin after using nanofibers showed a large number of polymorphonuclear chronic inflammatory cells and formation of new capillary beds.

CONCLUSIONS

The BCNS loaded with DOX and VEN may expedite healing and reduce neuropathy in the DFU of diabetic patients.

Chemical cross-linking on gelatin-hyaluronan loaded with hinokitiol for the preparation of guided tissue regeneration hydrogel membranes with antibacterial and biocompatible properties

The mechanical properties and structural stability of hydrogels and their performance in antidegradation can be enhanced by cross-linking them with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC). However, residual EDC compromises the biocompatibility of cross-linked hydrogels and the formability of un-cross-linked hydrogels. In this study, a facile process for preparing hydrogel regenerative membranes exerting antibacterial effects and containing gelatin/hyaluronic acid (G/HA) through solution casting was proposed. The membranes were cross-linked with EDC (G/HA-Ec-0H) and impregnated with two concentrations of the antibacterial agent of hinokitiol (G/HA-Ec-2H and G/HA-Ec-4H). Amide bonds formed, and the rate of active amino acid fixation was higher than 90%, which was directly proportional to the degree of cross-linking. The G/HA-Ec-2H and G/HA-Ec-4H groups with hinokitiol showed good antibacterial properties. The rate of hydrogel degradation decreased, and the integrity of sample morphology was maintained at more than 80% for over 3 days in the immersion. Then, the hydrogel structures relaxed and disintegrated through a rapid degradation reaction within 24 h. The biocompatibility results showed that low concentrations of hinokitiol did not affect cell viability. Moreover, hydrogel membranes after 14 days of cell incubation showed good cell adhesion and proliferation. In summary, the membrane biostability of the cross-linked gelatin/hyaluronan hydrogels was enhanced by EDC at a biocompatible concentration, and the functionalized group of G/HA-Ec-2H shows potential as a biodegradable material for biocompatible tissue-guarded regeneration membranes with antibacterial properties.

Antibacterial composite membranes of polycaprolactone/gelatin loaded with zinc oxide nanoparticles for guided tissue regeneration

The bacterial colonization of absorbable membranes used for guided tissue regeneration (GTR), as well as their rapid degradation that can cause their rupture, are considered the major reasons for clinical failure. To address this, composite membranes of polycaprolactone (PCL) and gelatin (Gel) loaded with zinc oxide nanoparticles (ZnO-NPs; 1, 3 and 6 wt% relative to PCL content) were fabricated by electrospinning. To fabricate homogeneous fibrillar membranes, acetic acid was used as a sole common solvent to enhance the miscibility of PCL and Gel in the electrospinning solutions. The effects of ZnO-NPs in the physico-chemical, mechanical and in vitro biological properties of composite membranes were studied. The composite membranes showed adequate mechanical properties to offer a satisfactory clinical manipulation and an excellent conformability to the defect site while their degradation rate seemed to be appropriate to allow successful regeneration of periodontal defects. The presence of ZnO-NPs in the composite membranes significantly decreased the planktonic and the biofilm growth of the Staphylococcus aureus over time. Finally, the viability of human osteoblasts and human gingival fibroblasts exposed to the composite membranes with 1 and 3 wt% of ZnO-NPs indicated that those membranes are not expected to negatively influence the ability of periodontal cells to repopulate the defect site during GTR treatments. The results here obtained suggest that composite membranes of PCL and Gel loaded with ZnO-NPs have the potential to be used as structurally stable GTR membranes with local antibacterial properties intended for enhancing clinical treatments.

Polymer-based wafers containing in situ synthesized gold nanoparticles as a potential wound-dressing material

Polymer-based wafers containing gold nanoparticles (AuNP) were prepared using κ-carrageenan (κC), locust bean gum (LBG) and polyvinyl alcohol (PVA) at ratios of 42/22/13% ^w/_w and 35/15/17% ^w/_w. The synthesized AuNPs were evaluated for their particle size and morphology. The produced wafers containing AuNPs were investigated for their physicochemical, morphological, mechanical, and swelling properties. In addition, bacterial barrier activity and in vitro cytotoxicity were also evaluated in this study. The AuNPs obtained were spherical in shape (~ 10-15 nm in diameter) and exhibited a single bell-shaped UV-vis absorption band centered ~ 540 nm. FT-IR spectra of the wafers containing AuNPs exhibited a shift of ν(O=S=O) absorption band toward a lower wavenumber and a shift of ν(OH) absorption band toward a higher wavenumber due to the coordination of OH groups to AuNPs and their interaction with O=S=O groups of κC, respectively. SEM images confirmed the porous structure of the produced wafers, being the surface area, mechanical properties, and swelling behavior directly affected by changing both the initial amount of [Au⁺³] and the composition of the wafers. Lastly, the produced wafers showed non-toxicity to NIH-3T3 fibroblast cells, and they also serve as a bacterial barrier. These findings endorsed the claim that the produced wafers containing AuNPs could be a promising material for wound dressing applications.

Formulation and Evaluation of Novel Thiolated Intra Pocket Periodontal Composite Membrane of Doxycycline

Localized intra-pocket, retentive, biodegradable, prolonged release thiolated membrane can provide an improved therapeutic efficacy of doxycycline at the site of action with evading off target side effects. To this end, thiolated chitosan-hyaluronic acid composite polymeric complex next-generation of the periodontal membrane was manufactured by solvent casting method. FTIR spectroscopic analysis displayed successful immobilization of thiol groups on the manufactured thiolated periodontal membrane. Moreover, XRD, DSC, AFM and TGA of the membrane confirmed the compatibility of ingredients and modifications in surface chemistry. The thiolated periodontal film was also investigated in terms of thickness, weight uniformity, water-uptake capacity, drug content, pH, entrapment efficiency, lysozymal degradation and release patterns. Also, mucoadhesion profile was explored on gingival mucosa. The immobilized thiol groups on thiolated chitosan and thiolated hyaluronate were found to be 168 ± 11 μM/g (mean ± SD, n = 3) and 189 ± 8 μM/g (mean ± SD, n = 3) respectively. Swelling capacity of the thiolated periodontal membrane was significantly ∼2-fold higher (p < 0.05) as compared to unmodified membrane. The obtained thiolated membrane depicted 3 -old higher mucoadhesive features as compared to the un-modified membrane. In vitro release kinetics indicated approximately more than 80% prolonged release within 7 days. Mechanical strength of the Thiolated bandage was also significantly ∼2-fold higher (p < 0.05) as compared to unmodified membrane. Ex-vivo retention study revealed enhanced retention of thiolated membrane as compared to unmodified membrane. In-vitro antimicrobial studies demonstrated that thiolated membrane could efficiently kill Porphyromonas gingivalis cells as compared to the native membrane. Moreover, ex-vivo biodegradation results indicated that 90% of the thiolated membrane was biodegradable in 28 days. Based on these findings, thiolated next-generation of the periodontal membrane seems to be promising for periodontitis therapy.

Bi-layered electrospun nanofibrous membrane with osteogenic and antibacterial properties for guided bone regeneration

Guided bone regeneration (GBR) membranes have the potential to prevent the invasion of epithelial and connective tissues as well as to maintain a stable space for facilitating the ingrowth of regenerative bone tissue. However, the bioactivity and regeneration potential of currently available membranes still need to be improved. In this study, a novel bi-layered membrane with both osteogenic and antibacterial functions was developed for GBR applications. The loose layer (LL) of the membrane was composed of conjugated electrospun poly (lactic-co-glycolic acid) (PLGA)/gelatin nanofibers incorporating dexamethasone-loaded mesoporous silica nanoparticles (DEX@MSNs), while the dense layer (DL) of the membrane consisted of traditionally electrospun PLGA nanofibers loaded with the broad-spectrum antibiotic doxycycline hyclate (DCH). Morphological results showed that the LL (DEX@MSNs/PLGA/Gel) membrane exhibited a porous and loosely packed structure, which was beneficial for cell adhesion and infiltration, while the DL (DCH/PLGA) membrane remained dense enough to act as a barrier. In vitro drug release tests indicated that both DEX and DCH followed a favorable sustained release profile. The cell viability evaluation suggested that the electrospun membranes possessed good cytocompatibility. Furthermore, in vitro osteogenesis analyses demonstrated that the DEX@MSNs/PLGA/Gel composite membrane possessed an enhanced osteoinductive capacity for rat bone marrow stem cells (BMSCs), which was verified by the increased alkaline phosphatase (ALP) activity, the enhanced calcium deposition, and the upregulated osteocalcin (OCN) expression. In vitro antimicrobial experiments revealed the effective antibacterial potency of the DCH/PLGA membrane. In conclusion, the prepared nanocarrier-incorporated bi-layered composite membrane with combined osteogenic and antibacterial properties may be a promising candidate for GBR application.