Gold nanoparticles aunps

The aptamer for thrombin was purchased from Sangon Biotechnology Co., Ltd. (Shanghai, People’s Republic of China) with high-performance liquid chromatography purification and mass spectrometry confirmation. The complementary sequence of thrombin aptamer modified with thiol used in this study is as follows: 5′-thiol–AGTCACCCCAACCTGCCCTACCACGGACT-3′. The underlined sequences can have a hairpin-like structure.
Thrombin-binding aptamer was as follows: 5′-AAAA GTCCGTG GTAGGGCA GGTTGGGGTGA CT-FAM-3′. The underlined sequences can be easily recognized by RecJf Exo.
Human α-thrombin with purity more than 95%, was obtained from Haematologic Technologies Inc (Essex, VT, USA). Exo was purchased from New England Biolabs (Beijing) Ltd (Beijing, People’s Republic of China). Gold nanoparticles (AuNPs) with an average diameter of 13±2 nm along with Tween 80 and other proteins were purchased from Sigma-Aldrich Chemical Co. (Shanghai, People’s Republic of China). All solutions that were used in the experiments were prepared with Milli-Q water (18.2 MΩ⋅cm). Human blood serum samples were obtained from Affiliated Hospital of Jiangsu University.

GDNF and rabbit anti-GDNF polyclonal antibody, bovine serum albumin (BSA), streptavidin, and gold nanoparticles (AuNPs) (5 nm, 10 nm, and 20 nm) were purchased from Sigma-Aldrich (Steinheim, Germany). The polymerase Klenow fragment exo- and deoxynucleoside triphosphates (dNTPs) were obtained from New England Biolabs (Ipswich, MA, USA). Other chemicals were purchased from standard commercial sources and were of analytical grade. All buffer solutions used in this study were prepared in our laboratory with ultrapure water.
The oligonucleotide sequences were synthesized and purified through high-performance liquid chromatography by Shanghai Sangon Biological Engineering Technology & Services Co. Ltd (Shanghai, People’s Republic of China). The oligonucleotide sequences are listed in Table 1.