Glutathione-responsive β-CD nanosponges (GSH-NSs) were prepared by a method developed by our group earlier 38 (link). Briefly, 2.0 g (1.76 mmol) of anhydrous β-CD was dissolved in 8 mL of DMSO with continuous stirring until a clear solution is formed. Later, 0.200 g (1.29 mmol) of 2-hydroxyethyl disulfide and 2.0 mL (14.35 mmol) of triethylamine was added as a catalyst. Finally, 5.5 g (24.48 mmol) of pyromellitic dianhydride was added to the solution with vigorous stirring to carry out the reaction. Gel-like mass was obtained within a few minutes which was incubated for the next 24 hours at room temperature to complete the reaction. At the end of the reaction, a solid monolith block of GSH-NSs was crushed to obtain a coarse powder followed by extensive washing with water and acetone. The prepared GSH-NSs were purified by Soxhlet extraction with acetone for a period of approximately 24 hours and air-dried at room temperature. GSH-NSs were kept in a desiccator for further use. The sulfur content within the GHS-NSs was determined by elemental analysis (Thermo Electron Corporation Flash EA 1112 series CHNS-O Analyzer) using an equal amount of V2O5 as a catalyst (2.5 mg).
Flashea 1112 series chns o analyzer
Manufactured by Thermo Fisher Scientific
The FlashEA 1112 series CHNS/O analyzer is a laboratory instrument designed for the determination of carbon, hydrogen, nitrogen, sulfur, and oxygen content in a wide range of organic and inorganic samples. The analyzer uses a combustion process to convert the sample material into simple gases, which are then separated and detected to provide quantitative analysis.
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5 protocols using flashea 1112 series chns o analyzer
1
Preparation of Glutathione-Responsive β-CD Nanosponges
2
CHNS Elemental Analysis of GSH/pH-NS
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CHNS elemental analysis was performed to quantify the sulfur content in the GSH/pH-NS and compare it with the theoretical value. The CHNS analyses were performed in triplicate in a Thermo Electron Corporation Flash EA 1112 series CHNS-O Analyzer, using 2,5-bis (5-tert-butyl-benzoxazol-2-yl) thiophene (BBOT) as an external standard. Approximately 2.5 mg of each sample was placed in a tin capsule. An approximately equal quantity of V2O5 was then added as a catalyst.
3
Spectroscopic Characterization of Compounds
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All reagents of commercial quality were used without further purification. The purity of the compounds was determined by elemental analysis and verified to be ≥95%. NMR spectra were recorded at 25°C on a Bruker Avance 400 FT spectrophotometer. The attenuated total reflectance IR spectra were recorded by means of a Nicolet-Nexus (Thermo Fisher) spectrophotometer by using a diamond crystal plate in the range of 4000–400 cm-1. Elemental analyses were performed by using a FlashEA 1112 series CHNS/O analyzer (Thermo Fisher) with gas-chromatographic separation. Electrospray mass spectral analyses (ESI-MS) were performed with an electrospray ionization (ESI) time-of-flight Micromass 4LCZ spectrometer. MS spectra were acquired in positive EI mode by means of a direct exposure probe mounting on the tip of a Re-filament with a DSQII Thermo Fisher apparatus, equipped with a single quadrupole analyzer.
4
NMR Spectroscopy and Elemental Analysis
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1HNMR spectra
were acquired by means of a Bruker AV300 or AV400 spectrophotometer,
using a mixture of DMSO-d6 and CF3COOD (one drop) to facilitate the complete solubilization
of the solids. The 19F{1H}-NMR spectrum of1 was instead recorded in DMSO-d6 after prolonged sonication. The 1H chemical shift values
are referenced to TMS, while the 19F{1H} chemical
shift is referenced to CFCl3. Elemental analyses were performed
on a FlashEA 1112 Series CHNS-O analyzer (ThermoFisher) with gas-chromatographic
separation.
were acquired by means of a Bruker AV300 or AV400 spectrophotometer,
using a mixture of DMSO-d6 and CF3COOD (one drop) to facilitate the complete solubilization
of the solids. The 19F{1H}-NMR spectrum of
are referenced to TMS, while the 19F{1H} chemical
shift is referenced to CFCl3. Elemental analyses were performed
on a FlashEA 1112 Series CHNS-O analyzer (ThermoFisher) with gas-chromatographic
separation.
5
Mg(II)-Binding Ligand Characterization
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All reagents of commercial quality were purchased from Sigma-Aldrich and used without further purification. The purity of the compounds was determined by elemental analysis and verified to be ≥95% for all synthesized molecules. NMR spectra were recorded at 25 °C on a Bruker Avance 400 FT spectrophotometer. The attenuate total reflectance IR spectra were recorded by means of a Nicolet-Nexus (Thermo Fisher) spectrophotometer by using a diamond crystal plate in the range of 4000–400 cm−1. Elemental analyses were performed by using a FlashEA 1112 series CHNS/O analyzer (Thermo Fisher) with gas-chromatographic separation. Electrospray mass spectral analyses (ESI-MS) were performed with an electrospray ionization (ESI) time-of-flight Micromass 4LCZ spectrometer. MS spectra were acquired in positive EI mode by means of a direct exposure probe mounting on the tip of a Re-filament with a DSQII Thermo Fisher apparatus, equipped with a single quadrupole analyzer. UV–Vis spectra were recorded on an Evolution 260 Bio Thermo spectrophotometer by using cells of 1 cm path length. UV-vis absorption spectra of 19 and 23 were registered using a ca. 10−5 M solution in methanol. Each metal/ligand system was studied by titrating a 2.8 ml sample of the ligand solution with a methanolic solution of Mg(CH3COO)2; 8–12 spectra of samples with M:L molar ratio ranging from 0 to 6 were measured.
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