Data on glycerol/tartaric acid-based copolymer containing ciprofloxacin for wound healing applications

This data article is related to our recently published research paper “Exploiting a new glycerol-based copolymer as a route to wound healing: synthesis, characterization and biocompatibility assessment", De Giglio et al. (Colloids and Surfaces B: Biointerfaces 136 (2015) 600–611) [1]. The latter described a new copolymer derived from glycerol and tartaric acid (PGT). Herein, an investigation about the PGT-ciprofloxacin (CIP) interactions by means of Fourier Transform Infrared Spectroscopy (FT-IR) acquired in Attenuated Total Reflectance (ATR) mode and Differential Scanning Calorimetry (DSC) was reported. Moreover, CIP release experiments on CIP-PGT patches were performed by High Performance Liquid Chromatography (HPLC) at different pH values.


b s t r a c t
This data article is related to our recently published research paper "Exploiting a new glycerol-based copolymer as a route to wound healing: synthesis, characterization and biocompatibility assessment", De Giglio et al. (Colloids and Surfaces B: Biointerfaces 136 (2015) 600-611) [1]. The latter described a new copolymer derived from glycerol and tartaric acid (PGT). Herein, an investigation about the PGT-ciprofloxacin (CIP) interactions by means of Fourier Transform Infrared Spectroscopy (FT-IR) acquired in Attenuated Total Reflectance (ATR) mode and Differential Scanning Calorimetry (DSC) was reported.

Data accessibility
Data is available with this article.

Value of the data
FT-IR spectra may help other researchers in the analysis of comparable polymeric structures. DSC data are useful to explain the CIP-PGT interactions. Data about CIP release from PGT-based patches provide insight into the antibiotic release at different pH values.

Data
FT-IR spectra acquired in ATR mode and DSC analysis are related to PGT, CIP and their mixture, while, HPLC measurements refer to CIP-loaded PGT casted on non-woven patches.

Materials
Chemical compounds used in this article: a new copolymer (PGT) was synthesized by using the following compounds: glycerol (PubChem CID: 753) and L-tartaric acid (PubChem CID: 444305), according to a procedure reported in [1]. Patches based on a non-woven tape impregnated by a mixture of PGT and ciprofloxacin hydrochloride (CIP) (PubChem CID: 62999) are proposed to provide a topical delivery vehicle to treat skin infections.

Fourier Transform Infrared Spectroscopy (FT-IR)
ATR spectra (Fig. 2) of CIP, PGT and CIP-loaded PGT (PGT/CIP 5:3 w/w ratio) were measured on a spectrum two Perkin-Elmer using the Universal ATR accessory (Single Reflection Diamond). The samples were analyzed without any preliminary preparative step. The peak wavenumbers and attributions of CIP, reported in Table 1, were in agreement with the literature data [2]. PGT copolymer and CIP-loaded PGT ATR peaks were also reported.

Thermal analysis by Differential Scanning Calorimetry (DSC)
DSC measurements were performed by a Perkin-Elmer DSC400, equipped with Pyris software for thermogram processing. Samples of 8-10 mg were placed in a flat bottomed aluminum pan and heated at a constant rate of 10°C/min, using dry nitrogen atmosphere as carrier gas, in a temperature range of 30-400°C. The instrument temperature and energy scales were calibrated using purified Indium (99.9%) as the standard reference material.    The thermal analysis is a valuable method to investigate drug-polymer interactions and to optimize formulations of pharmaceutical dosage forms [3]. DSC of plain drug, PGT copolymer and CIPloaded copolymer (PGT/CIP 5:3 w/w ratio), shown in Fig. 3, were performed to determine any change in the drug melting temperature, in order to investigate possible interactions between the drug and the copolymer.
The DSC data demonstrated endothermic peaks for CIP and PGT at 154°C and 108°C, respectively. The PGT-CIP mixture thermogram showed the disappearance of endothermic peaks of CIP and PGT and the appearance of another endothermic peak at 127°C. CIP melting point was found at 325°C followed by decomposition; this peak was anticipated to 310°C when CIP was included in PGT gel.

Ciprofloxacin release from PGT-based patches at different pH values
CIP release was monitored dipping the PGT impregnated patches in 10 ml of physiologic solution (NaCl 0.9%) at pH 5.0 or pH 7.4, equilibrated to 37 70.5°C in a thermostatic shaking incubator.
At pre-determined time intervals aliquots of 500 ml were withdrawn and replaced with fresh solution. CIP HPLC analyses were performed on an Agilent 1260 Infinity Chromatograph with a Multiple Wavelength (MW) detector, 20 ml injection loop. A reversed phase synergy column (15 cmx4.6 mm; 4 mm particles; Phenomenex) was eluted in isocratic mode, monitoring continuously the effluent at 280 nm [4]. A liter of mobile phase consisted of a mixture of 900 ml of 50 ml/L acetic acid, plus 50 ml acetonitrile and 50 ml methanol. The flow rate was maintained to 1.25 ml/min. Acquired data were processed by the Agilent Technologies ChemStation software for LC systems and compound quantification was carried out as previously reported [1].
Solubility is one of the properties which directly impact on bioavailability of an active pharmaceutical ingredient. The aqueous solubility of CIP is pH-dependent [5]. At neutral pH, the zwitterionic and unionised forms of CIP are dominant. In this form, CIP presents the minimum solubility. [6] Pathogenic bacteria prefer the neutral environment (pH 7.4) that characterizes subcutaneous tissue to the slightly acidic one of integer skin surface (pH 5.0) [6]. In this respect, CIP release from drug loaded PGT patches was performed in NaCl 0.9%, 37°C), varying only the medium pH. As shown in Fig. 4, no significant differences in the release profile were detected varying the pH of the release medium.