Mucoadhesive Properties Research Articles

Mucoadhesive in situ nasal gel of amoxicillin trihydrate for improved local delivery: Ex vivo mucosal permeation and retention studies

Orally administered amoxicillin is recommended as the first-line treatment of acute bacterial rhinosinusitis (ABR) and given in a high-dose regimen. However, the risk of various systemic adverse reactions and low oral bioavailability are unbearable, increasing the threat of antibiotic resistance. Therefore, nasal delivery of amoxicillin can be a potential approach for effectively treating ABR locally, as well as overcoming those drawbacks. In a way to guarantee the effectiveness for local therapy in nasal cavity, the permeation and retention properties are of significant importance considerations. Accordingly, the present work aimed to investigate the characteristics with respect to the nasal applicability of the in situ gelling amoxicillin trihydrate (AMT) and further evaluate its permeability and retention properties through human nasal mucosa. The lyophilized formulations were characterized utilizing the Differential Scanning Calorimetry (DSC) and X-ray Powder Diffraction (XRPD), and also evaluated for its polarity, reconstitution time, droplet size distribution, mucoadhesive properties, and ex vivo permeability and retention studies. The results confirmed that the in situ gelling AMT formulations possess adequate mucoadhesive behavior, especially the formulation containing 0.3 % of gellan gum. Substantially, the in situ gelling AMT formulations were able to retain the drug on the surface of nasal mucosa instead of permeating across the membrane; thus, suitable for treating nasal infections locally. Altogether, the in situ gelling systems demonstrates promising abilities as a delivery platform to enhance local application of AMT within the nasal cavity.

Synthesis of thiomer/nanoclay nanocomposites as a potential drug carrier: Evaluation of mucoadhesive and controlled release properties

Novel thiomer/nanoclay nanocomposites based on a thiomer and montmorillonite (MMT) were prepared in order to obtain a mucoadhesive material with controlled release properties for its potential use as drug carrier. The thiomer was synthesized by immobilization of L-cysteine in alginate mediated by carbodiimide reaction and further characterized by FT-IR and Ellman's reaction. Nanocomposites with growing concentrations of thiomer and MMT were prepared and analyzed by XRD, TGA and TEM. Rheological behavior of nanocomposite in contact with mucin and intestinal mucus were studied as in vitro and in situ mucoadhesion approach, showing until ∼10-fold increasing in the complex viscosity and ∼27-fold in elastic modulus when the amount of thiomer is increased. Higuchi and Korsmeyer-Peppas kinetic models were evaluated in order to study the release of deltamethrin from nanocomposite films. Release profiles showed a retard in the migration of the drug influenced by the amount of MMT (P < 0.05). Diffusion coefficient (D) showed a significant decrease (P < 0.0001) when concentration of MMT is increased reaching D = 4.18 × 10–7 m2 h–1, which resulted ∼7-fold lower in comparison with formulation without MMT. This hybrid nanocomposite can be projected as a potential mucoadhesive drug carrier with controlled release properties.

Eudragit® EPO, modified with 4-phenylboronic acid groups, as a novel polymeric excipient with enhanced mucoadhesive properties

Eudragit® EPO, modified with 4-phenylboronic acid groups, as a novel polymeric excipient with enhanced mucoadhesive properties

Design of experiment (DoE) of mucoadhesive valproic acid-loaded nanostructured lipid carriers (NLC) for potential nose-to-brain application

Epilepsy is a highly prevalent neurological disease and valproic acid (VPA) is used as a first-line chronic treatment. However, this drug has poor oral bioavailability, which requires the administration of high doses, resulting in adverse effects. Alternative routes of VPA administration have therefore been investigated, such as the nose-to-brain route, which allows the drug to be transported directly from the nasal cavity to the brain. Here, the use of nanostructured lipid carriers (NLC) to encapsulate drugs administered in the nasal cavity has proved advantageous. The aim of this work was to optimise a mucoadhesive formulation of VPA-loaded NLC for intranasal administration to improve the treatment of epilepsy. The Design of Experiment (DoE) was used to optimise the formulation, starting with component optimisation using Mixture Design (MD), followed by optimisation of the manufacturing process parameters using Central Composite Design (CCD).The optimised VPA-loaded NLC had a particle size of 76.1 ± 2.8 nm, a polydispersity index of 0.190 ± 0.027, a zeta potential of 28.1 ± 2.0 mV and an encapsulation efficiency of 85.4 ± 0.8%. The in vitro release study showed VPA release from the NLC of 50 % after 6 h and 100 % after 24 h. The in vitro biocompatibility experiments in various cell lines have shown that the optimised VPA-loaded NLC formulation is safe up to 75 µg/mL, in neuronal (SH-SY5Y), nasal (RPMI 2650) and hepatic (HepG2) cells. Finally, the interaction of the optimised VPA-loaded NLC formulation with nasal mucus was investigated and mucoadhesive properties were observed. The results of this study suggest that the use of intranasal VPA-loaded NLC may be a promising alternative to promote VPA targeting to the brain, thereby improving bioavailability and minimising adverse effects.

Enhanced mucoadhesive properties of ionically cross-linked thiolated gellan gum films

Localized oral drug delivery offers several advantages for treating various disease conditions. However, drug retention at the disease site within the oral cavity is indeed a significant challenge due to the dynamic oral environment. The present study aimed to develop a mucoadhesive inner layer for a three-layer mucoadhesive bandage suitable for localized oral drug delivery. using gellan gum (GG) biopolymer. Gellan gum (GG) was modified using L-cysteine moieties via carbodiimide chemistry. Subsequently, gellan gum solution at different extents of thiolation was ionically cross-linked using aluminum ammonium sulfate. Thiolated gellan gum films of uniform thickness were prepared using a solvent casting method. The thickness of bare gellan gum film was 0.035 ± 0.0043 mm, whereas the thiolated gellan gum films, GG 1S and GG 2S showed a thickness of 0.0191 ± 0.0011 mm and 0.0188 ± 0.0004 mm respectively. A high work of adhesion was noted for thiolated gellan gum (GG 2S) with a value of 10 N.mm while using porcine buccal mucosa. An average tensile strength of 48.2 ± 2.46 MPa was measured for thiolated gellan gum films irrespective of the extent of thiolation. The high work of adhesion, favorable cytocompatibility, desirable mechanical properties, and free swell capacity in saline confirmed the suitability of ionically cross-linked thiolated gellan gum films as an inner mucoadhesive layer for the mucoadhesive bandage.

In situ forming hydrogels based on modified gellan gum/chitosan for ocular drug delivery of timolol maleate

In situ forming hydrogels are suitable candidates for increasing drug residence time in ocular drug delivery. In this study, gellan gum (GG) was oxidized to form aldehyde groups and in situ gelling hydrogels were synthesized based on a Schiff-base reaction between oxidized GG (OGG) and chitosan (CS) in the presence of β-glycerophosphate. The effect of OGG and CS concentration on the physical and chemical properties of the resulting hydrogels was investigated. The FT-IR spectroscopy confirmed the chemical modification of OGG as well as the functional groups of the prepared hydrogels. The scanning electron microscope (SEM) revealed the highly porous structure of hydrogels. The obtained hydrogels indicated a high swelling degree and degradability. Also, the rheological studies demonstrated self-healing behavior, shear thinning, thixotropy, and mucoadhesion properties for the developed hydrogels. The results of in vitro and ex vivo studies showed that the timolol-loaded hydrogel with a higher amount of OGG has a higher release rate. Moreover, the MTT cytotoxicity test on bone marrow mesenchymal stem cells (BMSCs) confirmed that developed hydrogels are not toxic. The obtained results revealed that the developed hydrogels can be a desirable choice for the ocular drug delivery of timolol in the treatment of glaucoma.

Novel Acryloylated and Methacryloylated Nanocellulose Derivatives with Improved Mucoadhesive Properties.

In this work, three nanocellulose derivatives are synthesized with the aim of preparing new mucoadhesive materials. Nanocellulose is reacted with glycidyl methacrylate in dimethylsulphoxide, and with acryloyl and methacryloyl chloride in dimethylacetamide in the presence of 4-(N,N-dimethylamino)pyridine as a catalyst. These reactions are carried out under heterogeneous conditions, and the reaction products are characterized using various spectroscopic techniques, X-ray diffraction, atomic force microscopy, and thermogravimetric analysis. The Fourier-transform infrared spectra showed all the characteristic absorption bands typical for cellulose and also new peaks at 1720cm-1 for the carbonyl group (C═O) and 1639, 812cm-1 for the double bond (C═C). It is established that the crystal structure of the nanocellulose is slightly changed with derivatisation and the thermal stability of these derivatives increased. Mucoadhesive properties of nanocellulose and its derivatives is evaluated using the tensile test, rotating basket method, and fluorescence flow-through method. The retention of these polymers is evaluated on sheep oral mucosal tissue ex vivo using artificial saliva. Test results demonstrated that the new derivatives of nanocellulose have improved mucoadhesive properties compared to the parent nanocellulose.

Development of cashew-alginate microbeads and powdered dose forms: prospects for oral vaccine delivery in chickens

ABSTRACT Conventional oral vaccine delivery in poultry is challenging due to vaccine degradation in the gastrointestinal (GI) environment and the need for cold-chain storage. Microencapsulation offers a solution by protecting vaccines from GI degradation and improving stability. Natural polymers like alginate and cashew gum have mucoadhesive properties, making them promising candidates for oral vaccine delivery. This study developed cashew-alginate microbeads and a powdered dose form for oral vaccine delivery in chickens. The microbeads were created using ionotropic gelation, while the powdered form was obtained via freeze-drying. These formulations were characterized for size, shape, and stability using scanning electron microscopy (SEM), light microscopy, X-ray diffraction (XRD), and Energy Dispersive X-ray (EDX). Peak adhesion time (PAT) was determined using chicken intestinal and esophageal tissues, and antigenicity was assessed with in-vitro hemagglutination (HA) and hemagglutination inhibition (HI) assays. The microbeads exhibited a spherical shape with a porous structure, suggesting enhanced antigen accommodation. Hemagglutination Inhibition tests indicated that the experimental vaccine remained effective without cold-chain storage for three months. These findings suggest that cashew-alginate microbeads are promising for oral vaccine delivery in poultry.

A thermosensitive chitosan hydrogel: An attempt for the nasal delivery of dimethyl fumarate

Dimethyl fumarate (DMF) is a drug that is orally administered for the treatment of relapsing-remitting multiple sclerosis. However, DMF causes gastrointestinal side effects and flushing in 43 % of patients, which significantly contributes to treatment discontinuation. To reduce side effects and increase patient compliance, the aim of this study was to develop a thermosensitive chitosan/glycerophosphate hydrogel for the nasal administration of DMF. A binary system of DMF with hydroxypropyl-β-cyclodextrin (HP-β-CD) was made and included in the hydrogel precursor solution. The precursor solution (drug content, DMF stability, thermogelling properties, viscosity), and the resulting thermosensitive hydrogel (mucoadhesion, in vitro DMF permeation) were characterized. HP-β-CD was able to interact with DMF and improve its water solubility. The leader thermosensitive nasal solution, G1 solution, was loaded with approximately 92 % DMF, which remained stable for 21 days. The G1 solution formed a hydrogel in approximately 2–1 min; it had a pH of 6.8 ± 0.06 and caused no significant change in the osmolality of the simulated nasal medium. The G1 hydrogel showed good mucoadhesive properties and released DMF that permeated in vitro in a controlled manner. As a result, G1 is a potential new approach to exploit the intranasal administration of DMF for treating multiple sclerosis.

Comprehensive evaluation of xylometazoline hydrochloride formulations: Ex-vivo and in-vitro studies

Xylometazoline is a well-established nasal decongestant that has been used alone and in combination with dexpanthenol as an over the counter (OTC) medicine. Considering the possibility of further improvement of xylometazoline nasal formulations, hyaluronic acid (HA) was evaluated as an additional ingredient. The aim of this study was to investigate the permeation, mucosal retention, and mucoadhesion properties of a new xylometazoline-HA [Xylo-HA] formulation ex vivo and to explore the potential benefits of incorporating HA in the formulation in vitro. Sheep nasal mucosa was used in the ex vivo study, where Xylo-HA was compared with xylometazoline alone [Xylo-Mono], and in combination with dexpanthenol [Xylo-Dex] to understand the impact of formulation changes. The permeation of xylometazoline was generally low (Xylo-Mono 11.14 ± 4.75 %, Xylo-HA 14.57 ± 5.72 % and Xylo-Dex 11.00 ± 3.05 % of the applied dose). The steady state fluxes of xylometazoline were determined as 12.64 ± 3.52 μg/cm2h, 14.94 ± 3.38 μg/cm2h and 12.19 ± 2.05 μg/cm2h for Xylo-Mono, Xylo-HA and Xylo-Dex, respectively. No significant differences were observed between the formulations in the permeation nor mucosal retention studies (p > 0.05 for all), while Xylo-HA exhibited superior mucoadhesive proprieties (p < 0.05 for all). The effects on wound healing and barrier integrity of the three xylometazoline formulations were tested in vitro on HaCaT cells. To better elucidate the role of HA, an additional HA formulation without xylometazoline was prepared (HA-Mono). A scratch test was performed to evaluate wound healing, revealing that the test formulations did not achieve complete wound closure within 72 h and demonstrated a similar effect at the end of the testing period. To assess the effect on barrier integrity, cells were treated for 5 days with daily measurements of transepithelial electrical resistance (TEER). At the end of the experiment, Xylo-Dex showed a moderate 14 % increase in TEER, while Xylo-Mono did not significantly affect this parameter. TEER rose by 951 % in the Xylo-HA, and by 10497 % in the HA group, suggesting that incorporating HA led to enhanced barrier function. Further clinical studies are recommended to better understand the clinical implications and efficacy of the Xylo-HA formulation, with particular focus on the role of HA.

Development of mucoadhesive 3D-printed Carbopol/Eudragit/SNAC tablets for the oral delivery of enoxaparin: In vitro and ex vivo evaluation

3D-printed dosage forms comprised of Carbopol and Eudragit were fabricated through semi-solid extrusion, combining Enoxaparin (Enox) and the permeation enhancer SNAC in a single-step process without subsequent post-processing. Inks were characterized using rheology and Fourier-transform infrared (FTIR) spectroscopy. The stability of Enox in the fabricated dosage forms was assessed by means of Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) analysis. In vitro release studies revealed the release of Enox in a sustained manner, whereas ex vivo experiments demonstrated the mucoadhesive properties of the 3D-printed dosage forms and their ability to enhance Enox permeability across intestinal mucosa. Cellular assays (CCK-8 assay) revealed a dose- and time-dependent response following incubation with the 3D-printed dosage forms. The encapsulation of SNAC in the 3D-printed dosage forms demonstrated their capacity to increase the transcellularly transport of macromolecule across Caco-2 monolayer in a reversible manner, as confirmed by Transepithelial Resistance (TEER) measurements.

Tailored Sticky Solutions: 3D-Printed Miconazole Buccal Films for Pediatric Oral Candidiasis.

In this research, 3D-printed antifungal buccal films (BFs) were manufactured as a potential alternative to commercially available antifungal oral gels addressing key considerations such as ease of manufacturing, convenience of administration, enhanced drug efficacy and suitability of paediatric patients. The fabrication process involved the use of a semi-solid extrusion method to create BFs from zein-Poly-Vinyl-Pyrrolidone (zein-PVP) polymer blend, which served as a carrier for drug (miconazole) and taste enhancers. After manufacturing, it was determined that the disintegration time for all films was less than 10min. However, these films are designed to adhere to buccal tissue, ensuring sustained drug release. Approximately 80% of the miconazole was released gradually over 2h from the zein/PVP matrix of the 3D printed films. Moreover, a detailed physicochemical characterization including spectroscopic and thermal methods was conducted to assess solid state and thermal stability of film constituents. Mucoadhesive properties and mechanical evaluation were also studied, while permeability studies revealed the extent to which film-loaded miconazole permeates through buccal tissue compared to commercially available oral gel formulation. Histological evaluation of the treated tissues was followed. Furthermore, in vitro antifungal activity was assessed for the developed films and the commercial oral gel. Finally, films underwent a two-month drug stability test to ascertain the suitability of the BFs for clinical application. The results demonstrate that 3D-printed films are a promising alternative for local administration of miconazole in the oral cavity.

Formulation and Evaluation of Colon Targeted Mucoadhesive Microsphere of Aceclofenac

The aim of this research was to formulate and evaluate colon-targeted mucoadhesive microspheres of aceclofenac, an anti-inflammatory drug, to enhance its bioavailability and reduce gastrointestinal side effects. Aceclofenac- loaded microspheres were prepared using a variety of mucoadhesive polymers such as chitosan, sodium alginate, and Eudragit. The prepared microspheres were characterized for particle size, surface morphology, drug encapsulation efficiency, in vitro drug release, and mucoadhesion properties. The optimized formulation demonstrated a sustained drug release profile, efficient mucoadhesion, and enhanced stability in simulated colonic fluid. The findings suggest that mucoadhesive microspheres are a promising carrier for the targeted delivery of aceclofenac to the colon.

Thermosensitive and mucoadhesive Xanthan gum-based hydrogel for local release of anti-Candida peptide

A thermoresponsive and mucoadhesive hydrogel has been developed for the local delivery of a novel anti-Candida peptide. This antimicrobial peptide was custom-designed and synthesized, utilizing a natural peptide identified in the hemolymph of the freshwater crayfish Procambarus clarkii as a molecular scaffold. The hydrogel, fabricated from a xanthan gum/poly-N-isopropylacrylamide graft copolymer, demonstrates temperature-dependent viscoelastic properties and a pseudoplastic behaviour, making it suitable for potential administration in various tissues. Moreover, the high stability of the hydrogel (about 9 % weight loss after 24 h of incubation) in physiological fluids as well as its mucoadhesive properties indicate that it could withstand in the application site long enough to perform its intended function. Furthermore, the good cytocompatibility of the hydrogel and the peptide's release profile (approximately 90 % release within the first 24 h), coupled with its efficacy in inhibiting fungal growth (logarithmic reduction of 1.08 compared to the control), validates the prospective application of the formulation in managing mucosal and superficial skin C. albicans infections. This not only addresses concerns related to drug resistance but also establishes the hydrogel as a versatile platform for advanced drug delivery systems aimed at circumventing systemic administration of antifungal drugs for the treatment of superficial skin and mucosal candidiasis.

Development of a chitosan/propolis-based polymeric system: Characterization, biocompatibility, and modulation of transcription factor expression

Chitosan (CHT) and propolis (P) are natural materials with antiseptic, anti-inflammatory, antimicrobial, and mucoadhesive properties with many applications in orthopaedia dentistry. The objective of this study was to develop a low molecular weight (LMW) and medium molecular weight (MMW) chitosan polymeric system with propolis at different concentrations (0.31%, 0.62%, 1.25%, 2.5%, and 5%) and to evaluate the effect in terms of their cell interaction with dental pulp fibroblasts. FTIR spectra of both molecular weights CHT’s films with propolis show increased transmittance bands at 1730–1720 cm−1 and 1460 cm−1, indicating the presence of propolis ethanolic extract in the organic matrix. Contact angles test to determine hydrophobicity CHT films functionalized with propolis exhibit a more hydrophobic surface as propolis concentration increases. Cytotoxicity showed synergy between chitosan and propolis; the highest proliferation was observed in LMW CHT with 0.31% of propolis. Membranes made with CHT of both molecular weights plus propolis in an inflammatory stage (cells previously treated with LPS) can inhibit the expression of NF-k-B, MAPK, and VEGF. A polymeric system based on chitosan/ethanolic extract propolis could be a future alternative treatment for oral ulcers.

In Vitro and Ex Vivo Evaluation of Novel Methacrylated Chitosan-PNIPAAm-Hyaluronic Acid Hydrogels Loaded with Progesterone for Applications in Vaginal Delivery.

Miscarriage is defined as the loss of a pregnancy before 24 weeks and administration of progesterone in pregnancy has considerably decreased the risk of premature birth. Progesterone (PGT) starting from the luteal phase stabilizes pregnancy, promotes differentiation of the endometrium, and facilitates the implantation of the embryo. Within the present study, novel hybrid hydrogels based on chitosan methacrylate (CHT), hyaluronic acid (HA), and poly(N-isopropylacrylamide) (PNIPAAm) for vaginal delivery of progesterone were evaluated. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) for structural identity assessment and evaluation of their morphological aspects. The ability to swell, the release capacity, enzymatic degradation, cytotoxicity, and mucoadhesion were also reported. The characterized hydrogels demonstrated mucoadhesive properties in contact with the vaginal tissue of swine and bovine origin as substrates, and biodegradability and controlled release in a simulated vaginal environment. Cytocompatibility tests confirmed the ability of the hydrogels and progesterone to support cell viability and growth. The results showed pH-dependent behavior, controlled drug release, good cytocompatibility, and mucoadhesive properties. The hydrogels with higher chitosan amounts demonstrated better bioadhesive properties. This study provides insights into the potential of these hydrogels for the controlled vaginal delivery of progesterone, with promising therapeutic effects and no cytotoxicity observed. The experimental results indicated that a composition with a moderate content of PNIPAAm was suitable for the controlled delivery of progesterone.

Eudragit-maleimide as total denture base material: Proof of concept for a promising mucoadhesive strategy

AimTo develop an Eudragit S100-2(aminoethyl) maleimide (ES100-AEMal) conjugate as total denture base material candidate and to prove mucoadhesive properties. Methods2-(N-aminoethyl) maleimide (AEMal) was attached to Eudragit S100 (ES100) backbone via amide bond formation resulting in ES100-AEMal. After characterization of the product via nuclear magnetic resonance, infrared spectroscopy, and quantification of attached maleimide groups by a quantification assay kit, safety was assessed following the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay towards Caco-2 cells and fibroblasts. In addition, membrane damage was tested using human erythrocytes. Mucoadhesive properties were examined on gingiva in terms of rheometry and detachment time. ResultsThe successfully synthesized conjugate ES100-AEMal presented a 15 % degree of modification and no toxicity or membrane damage could be observed after one day of incubation. Mucoadhesiveness exhibited 239.91-fold, 490.6-fold and 24.15-fold increase in elastic modulus, viscous modulus, and dynamic viscosity, respectively. Furthermore, detachment time was enhanced 47.5-fold. ConclusionES100-AEMal demonstrated enhancement in gingival mucoadhesiveness maintaining biocompatibility.

Chitosan/Hesperidin Nanoparticles for Sufficient, Compatible, Antioxidant, and Antitumor Drug Delivery Systems.

One flavonoid glycoside with demonstrated therapeutic potential for several illnesses, including cancer, is hesperidin. However, because of its limited bioavailability and solubility, it is only marginally absorbed, necessitating a delivery mechanism to reach the intended therapeutic target. Additionally, the cytoskeleton of crustaceans yields chitosan, a naturally occurring biopolymer with mucoadhesive properties that has been used to improve the absorption of advantageous chemical substances like flavonoids. Chitosan/hesperidin nanoparticles (Hes-Nanoparticles) were made using the ion gelation technique. The synthesis of Hes-Nanoparticles was confirmed by several characterization methods, including the swelling test, zeta potential, particle size, FTIR, XRD, TEM, and SEM. DPPH and ABTS were used to demonstrate radical scavenging activity in antioxidant assays of chitosan, hesperidin, and the synthesized Hes-Nanoparticles. In addition, by a viability assay against MDA-MB-231, the anticancer efficacies of chitosan, hesperidin, and the synthesized Hes-Nanoparticles were assessed. Furthermore, annexin-V/PI double staining and the cycle of cell analysis were determined by flow cytometry. The results displayed that Hes-Nanoparticles have higher antioxidant activity than chitosan and hesperidin alone. Also, it has been demonstrated that Hes-Nanoparticles are more effective in early cell cycle arrest, suppressing the viability of cancer cells, and increasing cell apoptosis than chitosan and hesperidin alone. In conclusion, Hes-Nanoparticles demonstrated more antioxidant and antitumor activities than chitosan and hesperidin alone. Moreover, it has been established that Hes-Nanoparticles, in a highly soluble form, increase activity in contrast to the poorly soluble form of hesperidin alone.

Exploring Mucoadhesive and Toxicological Characteristics Following Modification of Linear Polyethylenimine with Various Anhydrides.

Linear polyethylenimine (L-PEI) has numerous applications, such as in pharmaceutical formulations, gene delivery, and water treatment. However, due to the presence of secondary amine groups, L-PEI shows a relatively high toxicity and low biocompatibility. Here, various organic anhydrides were used to modify L-PEI to reduce its toxicity and enhance its functionality. We selected methacrylic anhydride, crotonic anhydride, maleic anhydride, and succinic anhydride to modify L-PEI. The structure of the resulting derivatives was characterized using 1H NMR and FTIR spectroscopies, and their behavior in aqueous solutions was studied using turbidimetric and electrophoretic mobility measurements over a broad range of pHs. A fluorescence flow through method determined the mucoadhesive properties of the polymers to the bovine palpebral conjunctiva. Methacrylated L-PEI and crotonylated L-PEI showed strong mucoadhesive properties at pH 7.4, likely due to covalent bonding with mucin thiol groups. In contrast, maleylated and succinylated L-PEI were poorly mucoadhesive as the pH was above their isoelectric point, resulting in electrostatic repulsion between the polymers and mucin. The toxicity of these polymers was evaluated using in vivo assays with planaria and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay in human alveolar epithelial cells. Moreover, the irritancy of polymers was assessed using a slug mucosa irritation assay. The results demonstrated that anhydride modification mitigated the adverse toxicity effects seen for parent L-PEI.

Thiolated nanoclays as a potential mucoadhesive material: Optimization by design of experiments and multivariate regression

An integrated strategy based on design of experiments (DoE) and multivariate regression was carried out to produce an optimized surface functionalized nanoclay (Mt–SH) with potential mucoadhesive properties. A mercaptosilane was grafted in montmorillonite in order to immobilize thiol groups (–SH) on the clay. The functionalization was confirmed by IR, TGA, XRF and XRD analyses. Five variables involved in the synthesis were optimized in order to maximize two responses: mass of functionalized nanoclay and amount of thiol groups attached in the clay surface. This optimization was performed by a two–step DoE strategy using Plackett–Burman and Box–Behnken designs. The five variables and two responses were simultaneously calibrated in a single ANOVA–validated PLS regression model. Analyzing scores, loading and surface response plots, the main processing variables, interactions and quadratic terms were found achieving the optimal processing conditions for the synthesis. The quadratic model (R2 > 0.8589) predicted an optimized functionalized nanoclay of mass 3.29 ± 0.13 g of Mt–SH with 19.65 ± 0.78 μmol –SH per g Mt–SH (P < 0.05). The optimized Mt–SH was evaluated by in vitro and in situ mucoadhesion assays with porcine mucin and fresh intestinal mucus by using rheometry. The complex viscosity showed an increase of ∼54-fold higher compared to the unmodified Mt, and ∼12.8-fold increase in the elastic modulus, which indicates a more resistance to elastic deformation probably due to an increase in cross-linking points between Mt–SH and mucus. The formation of disulfide bonds between thiol groups from Mt–SH and glycoproteins in the mucin could be a reasonably explanation which shows a correlation respect other thiolated materials which show the same mucoadhesion properties. These results could project this functionalized silicate material as a potential mucoadhesive prospect for pharmaceutical applications.