Ultrospec 3100 pro spectrophotometer

For scanning electron microscopy (SEM), mesh fragments (1 × 1 cm²) were coated by immersion in the formulated gels (n = 3 each) under sterile conditions and the coating was air-dried overnight at room temperature, in a Telstar AV 30/70 type-II vertical laminar flow hood (Telstar S.A., Madrid, Spain). Dried samples were placed onto aluminium pin stubs, metalized with gold palladium and examined in a JSM-IT500 InTouchScope™ SEM (JEOL Ltd., Akishima, Tokio, Japan). Uncoated meshes (n = 3) were included as control.
Spectrophotometric analyses were performed to record the UV–Vis absorption spectra of CHX- and RIF-loaded biopolymer gels. To determine the spectrum of the gel carrier, measurements were also performed in drug-free 1% CMC. Freshly prepared gels were allowed to stabilize for 24 h at room temperature prior to carry out the measurements, which were recorded in triplicate. An Ultrospec 3100 Pro spectrophotometer (Amersham Biosciences, Little Chalfont, UK) with a wavelength accuracy of 1 nm, a 10 mm matched quartz cell and in the spectral range of 200 to 800 nm, was used. To avoid exceeding the detection threshold of this technique, RIF-gel concentration was diluted (1:3) in CMC 1%.

Spectrophotometric assays were carried out to determine whether the presence of the coated meshes inhibited the bacterial growth in culture. As previously described, samples from the different groups (n = 6 per group per strain) were immersed in 3 mL of LB broth, inoculated with 1 mL of the corresponding bacteria and incubated 37 °C for 24 h. As blank, mesh samples immersed in 3 mL of LB broth plus 1 mL of sterile 0.9% saline were kept under the same conditions. Following incubation, the liquid was aspirated, vortexed, and measured by spectrophotometry (OD600) using an Ultrospec 3100 Pro spectrophotometer (Amersham Biosciences, Little Chalfont, UK). Results were expressed as the mean absorbance recorded for the different study groups.

Commercial reagents were purchased from Acros Organics, Aldrich, and Fluka. Solvents were used without further purification and distillation. Column chromatography was carried out on silica gel 60 0.040–0.063 mm (Merck, Darmstadt, Germany). Thin layer chromatography was performed on silica gel 60F₂₅₄ aluminum foil (Merck, Darmstadt, Germany). NMR spectra were recorded on an AMX III-400 spectrometer (Bruker, Billerica, USA) with an operating frequency of 400 MHz and 300 MHz for ¹H NMR (solvent—DMSO-d₆, Me₄Si as internal standard) and 100.6 MHz for ¹³C NMR. UV spectra were recorded on an Ultrospec 3100 pro spectrophotometer (Amersham Biosciences, Chicago, USAs) in ethanol. High-resolution mass spectra were recorded on a Bruker Daltonics MicrOTOF-Q II device using electrospray ionization mass spectrometry (ESI-MS). The measurements were carried out in the mode of positive ions in accordance with the previously applied conditions [32 (link)].