Fabrication and characterization of chitosan film impregnated ciprofloxacin drug: A comparative study

Tuning glycerol plasticization of chitosan with boric acid

Chitosan-based bioplastics are attractive biodegradable alternatives to petroleum-derived plastics. However, optimizing the properties of chitosan materials to fit a particular application or obtain a desired property is not a trivial feat. Here, we report the tunability of glycerol-plasticized chitosan films with the addition of boric acid. In combination, glycerol and boric acid form neutral complexes that alter the hydrogen-bonding face of the plasticizer and ultimately limit glycerol's ability to plasticize chitosan. Thus, we found that chitosan films containing glycerol-boric acid complexes were less flexible, had increased thermal transition temperatures, and showed more uniform morphologies. Structural, thermal, mechanical and morphological characterization was performed using ATR-FTIR, TGA and DSC, DMA, and SEM respectively. Molecular-level interactions of the neutral boron complexes and D-glucosamine, the repeat unit of chitosan, were also investigated used NMR and ATR-FTIR. The results of this work demonstrate the necessity of specific hydrogen-bonding interactions between the plasticizer and the polymer for effective plasticization, an important insight into the plasticization mechanism of chitosan films. Furthermore, the formation of complexes with glycerol is a novel and convenient method for tuning the physical properties of chitosan films.

Synthesis and Characterization of Antibacterial Chitosan Films with Ciprofloxacin in Acidic Conditions

This work presents the results of research on obtaining chitosan (CS) films containing on their surface ciprofloxacin (CIP). A unique structure was obtained that not only gives new properties to the films, but also changes the way of coverage and structure of the surface. The spectroscopic test showed that in the process of application of CIP on the surface of CS film, CIP was converted from its crystalline form to an amorphic one, hence improving its bioavailability. This improved its scope of microbiological effect. The research was carried out on the reduction of CIP concentration during the process of CIP adhesion to the surface of chitosan films. The antibacterial activity of the CS films with and without the drug was evaluated in relation to Escherichia coli and Staphylococcus aureus, as well as Candida albicans and Penicillium expansum. Changes in the morphology and roughness of membrane surfaces after the antibacterial molecule adhesion process were tested with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Structural analysis of CS and its modifications were confirmed with Fourier-transform spectroscopy in the infrared by an attenuated total reflectance of IR radiation (FTIR-ATR) and solid-state nuclear magnetic resonance (NMR).

New Zinc-Based Active Chitosan Films: Physicochemical Characterization, Antioxidant, and Antimicrobial Properties

The improvement of the antioxidant and antimicrobial activities of chitosan (CS) films can be realized by incorporating transition metal complexes as active components. In this context, bioactive films were prepared by embedding a newly synthesized acylpyrazolonate Zn(II) complex, [Zn(Q^PhtBu)₂(MeOH)₂], into the eco-friendly biopolymer CS matrix. Homogeneous, amorphous, flexible, and transparent CS@Zn_n films were obtained through the solvent casting method in dilute acidic solution, using different weight ratios of the Zn(II) complex to CS and characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), Raman, and scanning electron microscopy (SEM) techniques. The X-ray single-crystal analysis of [Zn(Q^PhtBu)₂(MeOH)₂] and the evaluation of its intermolecular interactions with a protonated glucosamine fragment through hydrogen bond propensity (HBP) calculations are reported. The effects of the different contents of the [Zn(Q^PhtBu)₂(MeOH)₂] complex on the CS biological proprieties have been evaluated, proving that the new CS@Zn_n films show an improved antioxidant activity, tested according to the DPPH method, with respect to pure CS, related to the concentration of the incorporated Zn(II) complex. Finally, the CS@Zn_n films were tried out as antimicrobial agents, showing an increase in antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus) with respect to pure CS, when detected by the agar disk-diffusion method.

An Up-to-Date Review of Biomaterials Application in Wound Management

Whether they are caused by trauma, illness, or surgery, wounds may occur throughout anyone's life. Some injuries' complexity and healing difficulty pose important challenges in the medical field, demanding novel approaches in wound management. A highly researched possibility is applying biomaterials in various forms, ranging from thin protective films, foams, and hydrogels to scaffolds and textiles enriched with drugs and nanoparticles. The synergy of biocompatibility and cell proliferative effects of these materials is reflected in a more rapid wound healing rate and improved structural and functional properties of the newly grown tissue. This paper aims to present the biomaterial dressings and scaffolds suitable for wound management application, reviewing the most recent studies in the field.

Understanding the Molecular-Level Interactions of Glucosamine-Glycerol Assemblies: A Model System for Chitosan Plasticization

Glycerol is the most widely used plasticizer for the biopolymer chitosan. However, there remains a lack of understanding of the molecular-level interactions between chitosan and glycerol. Here, we describe an in-depth spectroscopic study of the intermolecular interactions between the monomeric repeating unit of chitosan, glucosamine, and the plasticizer glycerol. Infrared and nuclear magnetic resonance spectroscopy were used to probe glucosamine assembly at high and low concentrations to establish diagnostic signals for intra- and intermolecular glucosamine interactions. Systematic addition of glycerol was found to disrupt intramolecular glucosamine hydrogen bonds and promote glucosamine self-assembly. Furthermore, we observed a significant preference for glycerol binding to the amine functionality of glucosamine. These findings indicate that the plasticization of chitosan with glycerol requires a specific binding motif and likely occurs via the gel theory mechanism.

Non-intuitive Behavior of Polymer-Ciprofloxacin Nanoconjugate Suspensions: a Tool for Flexible Oral Drug Delivery

Ciprofloxacin (CPX) is prone to spontaneous self-aggregation and formation of supramolecular dimers (π - π stacking) due to its complicated surface chemistry which has been associated with its anomalous solubility and instability in aqueous systems particularly near neutral pH. The surface characteristic of ciprofloxacin was modified through non-intuitive counterion interaction between CPX and diethylaminoethyl dextran (DDEX) to form nanoconjugate assembly. The CPX-DDEX nanoconjugate was confirmed by FTIR, SEM, DSC, TGA, and ¹H-NMR. The DSC thermograms showed a remarkable 20% reduction in the melting temperature (T_m) of CPX from 268.57±1.11°C to 214.36±1.0211°C and 78% reduction in enthalpy of fusion (ΔH_f) from 59.84 kJ/mol (180.59 J/g) to 12.90 kJ/mol (38.92 J/g), indicating increased solubility and dissolution efficiency. DDEX polymer alone exhibited pseudoplastic characteristics however with more viscous rather than elastic response, while the CPX-DDEX nanoconjugate suspensions exhibited remarkable elastic behavior with significantly increased storage modulus (G') thus controlling and extending the release of CPX. The reconstituted freeze-dried CPX-DDEX nanoconjugate suspension was chemically stable throughout the 90-day study both in the refrigerator and at controlled room temperature, while the aqueous suspension of pure CPX without DDEX was only stable for 72 and 24 h, respectively. The dissolution efficiency of the CPX-DDEX nanoconjugate suspensions increased with increasing molar concentration of DDEX to a maximum of 100% at 50 μM of DDEX followed by a remarkable decrease within the 3-week study. It was apparent that the dissolution efficiency was governed by a critical balance between the CPX solubility and the viscoelastic characteristics of the polymeric nanoassembly. This study demonstrates the potential application of polymer-drug nanoconjugation formulation design to stabilization and flexible delivery of CPX from aqueous suspension systems. Graphical abstract.

Chitosan derivatives-based films as pH-sensitive drug delivery systems with enhanced antioxidant and antibacterial properties

The purpose of this study was to develop and characterize chitosan (Ch)-based films incorporated with varying molecular weight (Mw) and acetylation degree (AD) chitosan-depolymerization-products (CDP), to be applied as drug delivery materials. As compared to Ch-film, optical and antioxidant potentials of Ch/CDP-based films were improved, particularly using low Mw and AD-CDP. Whereas, films water resistance, mechanical and antibacterial properties increased as CDP-Mw increased and AD decreased. For the thermal and swelling behaviors, better values were obtained using higher Mw and AD-CDP. Further, to assess their in vitro ciprofloxacin (CFX)-release behavior, loaded-CFX Ch/CDP-based films, crosslinked using glutaraldehyde, were prepared. Expect of elongation at break, crosslinked CFX-loaded films showed increased optical, water resistance, tensile strength and thermal properties, as compared to unloaded films. The CFX-release profiles indicated that a slower and sustained release was observed, particularly when using lower Mw and AD-CDP, and mainly for the crosslinked films during 48 h. These films can release CFX for up to 54% in 6 and 24 h, at pH 1.2 and 7.4, respectively. Through this study, novel biodegradable, swellable and pH-sensitive crosslinked Ch/CDP-based films may be considered as suitable and promising drug delivery systems.

Effect of plasticizer and surfactant on the properties of poly(vinyl alcohol)/chitosan films

The objective of this study was to develop eco-friendly films based on poly(vinyl alcohol) (PVA) and chitosan (CTS) with the addition of plasticizer (glycerol or sorbitol) and surfactant (cocamidopropyl betaine). The properties of the obtained polymeric films were determined by contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), mechanical tests, and moisture content analysis. The results indicated that four-component blends had high surface hydrophilicity and surface roughness due to the presence of the surfactant. Glycerol incorporation into PVA/CTS blends resulted in higher flexibility and greater water absorption capacity of the three- and four-component polymeric blends compared with these blends with sorbitol. By contrast, the addition of the surfactant to the materials is essential for their application in personal hygiene products as disposable wipes.

Chitosan-induced Synergy for Extended Antimicrobial Potency and Enhanced In Vitro Drug Release of Free Base Ciprofloxacin Nanoplexes

BACKGROUND

Ciprofloxacin free base is practically insoluble in aqueous medium (0.0011 and 0.09 mg/mL at 25 and 37°C respectively). Its inorganic salt form (ciprofloxacin hydrochloride) is more soluble in water (1.35 mg/mL) however when administered orally, it exhibits decreased solubility in the stomach due to common ion effects. Ciprofloxacin free base was used in this study because of its greater hydrophobicity than its hydrochloride salt, which is required for effective permeability and potent antibacterial activity.

OBJECTIVE

The purpose of this study is to enhance oral solubility and bacterial cell permeability of the free base ciprofloxacin (CPX) using a single step CPX-chitosan (CT) selfassembly to form nanoplexes with organic counterions. It was envisioned that this would allow the delivery of larger amounts of active drug into the microorganisms.

METHODS

Ciprofloxacin-chitosan nanocomplex (nanoplex) was prepared using low energy electrostatic self-assembly technique previously described. Formation of eutectic nanoplex was confirmed using FTIR, DSC, TGA and SEM. The saturated solubility, in vitro release kinetics and mechanism of drug release were determined using mathematical models. Potency and synergism were determined from the inhibition zones, minimum inhibitory concentration (MIC) and Fractional Inhibitory Concentration (FIC) of the nanoplexes using Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.

RESULTS

Formation of CPX-CT eutectic adduct polymeric nanoplexes was confirmed with FT-IR and DSC and SEM revealed the conversion of rod-like crystals of CPX (117 μm long) into spherical nanostructures (23-503 nm) dictated by pH, ionic strength and concentration of CT. The solubility of free base CPX increased to a maximum of 32.77 mg/mL compared to 0.0011-0.09 mg/mL reported in literature and dissolution efficiency increased to a maximum of 100% within 72 h. The synergistic effect of CT on antimicrobial activity of CPX was quantified, for the first time, using Fractional Inhibitory Concentration (FIC) of the nanoplexes. FIC was less than 0.5 in both Gram positive (0.031-0.250) and Gram negative (0.036-0.281) microorganisms used in this study, confirming synergistic enhancement of antimicrobial efficacy of CPX.

CONCLUSION

It is evident that the design of drug-polymer nanocomplex formulation provides a platform for the synergistic enhancement of therapeutic potency of antibiotics.