Biflex 4 maldi tof ms

To synthesize cystine dimethacrylate (CDA), a redox-responsive crosslinker, L-cystine (0.48 g, 2 mmol) was dissolved with 5 mL DI water and 1 mL TEA was added to the solution. After complete dissolution of L-cystine, 2 mL MA was added dropwise into the solution. The mixture was then stirred vigorously and the reaction was allowed for 48 h at room temperature. Following the reaction, TEA and unreacted MA were extracted with diethyl ether. Then the pH value of the resulted solution was adjusted to 2 with hydrochloric acid. The sample was then lyophilized and the final product was obtained as an off-white powder. Its molecular structure was confirmed by ¹HNMR (Varian Inova-500M, Varian Inc., Palo Alto, USA) with CO(CD₃)₂ (d-Acetone) as the solvent and tetramethylsilane (TMS) as the internal standard. Its molecular weight was confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF, Bruker Biflex IV MALDI-TOFMS) mass spectrometry.

Nuclear magnetic resonance (NMR) spectra were collected on a Bruker 300 MHz NMR spectrometer. Spectra are reported in parts per million (ppm) on the δ scale relative to the residual solvent as an internal standard. Size exclusion chromatography (SEC) was performed on a Hitachi Chromaster system equipped with an RI detector and an 8 μm, mixed bed, 300 × 7.5 mm cm PL aquagel–OH mixed medium column. 96-well plate assays (ELISA, carbazole) were analyzed using a Varioskan LUX multimode microplate reader. Matrix-assisted laser desorption ionization coupled with time-of-flight (MALDI-TOF) analysis was acquired via a Bruker Biflex IV MALDI-TOF MS in positive ion mode using sinapinic acid matrix. Bright field and fluorescence microscopy images were taken using ZEISS Axio Observer microscope. Radioactive thymidine assays were analyzed using a Beckman Coulter LS6500 Liquid Scintillation Counter.