Fluorescein isothiocyanate (fitc)

Chitosan (50 kDa, deacetylation degree 85%) was purchased from Jinan Haidebei Marine Bioengineering Co., Ltd, Shandong, China. Insulin (INS, 21 IU/mg) was from Dingguo Biotech Co., Ltd, Shanghai, China. HPMCP (HP-55S) was from Huzhou Mizuda Hope Bioscience Co., Ltd, Huzhou, China. Alloxan was from Sigma-Aldrich (Chicago, IL). Fluorescein isothiocyanate (FITC) and Rhodamine B (RhB) were from Tokyo Chemical Industry Co., Ltd, Tokyo, Japan. Sulfo-Cyanine5 NHS ester (Cy5) was from Lumiprobe, Hunt Valley, MD. Bicinchoninic acid (BCA) protein assay kit was from Thermo Fisher Scientific Inc, Waltham, MA. DMEM, fetal bovine serum, MEM non-essential amino acid solution, L-glutamine, penicillin and streptomycin were from GIBCO BRL Life Technologies Inc., Carlsbad, CA. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) was from Promega Co., Madison, WI. 2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride (DAPI) was from Beyotime Institute of Biotechnology, Jiangsu, China. DAPI Fluoromount-G^TM was from Yeasen Biotechnology, Shanghai, China. All other chemicals were of analytical grade and from Sinopharm Chemical Reagent Co., Ltd, Shanghai, China.

Exenatide (EXE) was purchased from Chinese Peptide Company Co., Ltd. (Hangzhou, Zhejiang, China). Zein, casein, cholic acid (CA, 98%) and glycocholic acid hydrate (GCA, ≥ 97%) were from Sigma-Aldrich (Shanghai, China). Hypromellose phthalate (HP, HP-55S) was from Huzhou Mizuda Hope Bioscience Co., Ltd. (Huzhou, Zhejiang, China), and was purified by dialysis and lyophilization. Phosphatidylcholine (PC, egg yolk lecithin PL-100 M, 80% phosphatidylcholine) was from A.V.T. Pharmaceutical Co., Ltd. (Shanghai, China). Deoxycholic acid (DCA, > 99%), rhodamine B isothiocyanate (RITC, conjugation grade), pepsin (from porcine stomach, 3000–3500 NFU/mg), pancreatin (pancreatin-8.0, from porcine pancreas, protease 214 USP.U/mg, amylase 214 USP.U/mg and lipase 24.2 USP.U/mg), colchicine (reagent grade) and chlorpromazine (> 98%) were from Sangon Biotech Co., Ltd. (Shanghai, China). Sulfo-cyanine 5 NHS ester (Cy5, analytical grade) was from Lumiprobe Corporation (Maryland, USA). Fluorescein isothiocyanate (FITC) was from Tokyo Chemical Industry Co. Ltd. (Tokyo, Japan). All culture reagents and materials were from Thermo Fisher Scientific Inc. (Shanghai, China). All other reagents were from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

Phos-tag acrylamide, acrylamide, N,N′-methylene-bis-acrylamide (TEMED), hydroxypropyl cellulose (HPC), N,N,N′,N′-tetramethylethylenediamine, EDTA, and 2,2′-azobis [2-methyl-N-(2-hydroxyethyl) propionamide] were obtained from FUJIFIRM Wako Pure Chemical Corporation Co., Ltd. (Tokyo, Japan). FITC was purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). β-Casein, monophosphopeptide was obtained from Cosmo Bio Co., Ltd. (Tokyo, Japan). DTAF and NBD-F were purchased from Sigma-Aldrich (Tokyo, Japan). The PDMS base and curing reagent (Sylgard 184) were purchased from Dow Corning Toray Co. Ltd. (Tokyo, Japan), and silicon wafers were procured from Kyushu Semiconductor KAW Co., Ltd. (Fukuoka, Japan). HPC (0.5% w/v) was added to all the buffers to prevent adsorption of the samples or/and fluorescent reagents to the PDMS/glass chip.
A PDMS microchannel was fabricated by the conventional soft lithography technique. The cross-channel chip consisted of three 5.8 mm and one 27.2 mm-long channels (100 µm width × 30 µm depth), as shown in Figure 1a. After creating the reservoir wells (2.5 mm diameter) with a piercer, these microchannels were directly bonded to the slide-glass via plasma treatment (YHS-R, SAKIGAKE-Semiconductor Co. Kyoto, Japan). An image of the produced PDMS/glass microchip is shown in Figure 1b.