Fu Yu, Liu Lin, Li Xiaodong, Chen Hongda, Wang Zhenxin, Yang Wensheng, Zhang Hua, Zhang Huimao
College of Chemistry, Jilin University Changchun 130021 P. R. China.
Department of Radiology, The First Hospital of Jilin University Changchun 130021 P. R. China
RSC Adv. 2021 Jan 11;11(4):2213-2220. doi: 10.1039/d0ra08171j. eCollection 2021 Jan 6.
Herein, a fluorescence turn-on nanosensor (MnIO@pep-FITC) has been proposed for detecting trypsin activity and through covalently immobilizing an FITC modified peptide substrate of trypsin (pep-FITC) on manganese-doped iron oxide nanoparticle (MnIO NP) surfaces a polyethylene glycol (PEG) crosslinker. The conjugation of pep-FITC with MnIO NPs results in the quenching of FITC fluorescence. After trypsin cleavage, the FITC moiety is released from the MnIO NP surface, leading to a remarkable recovery of FITC fluorescence signal. Under the optimum experimental conditions, the recovery ratio of FITC fluorescence intensity is linearly dependent on the trypsin concentration in the range of 2 to 100 ng mL in buffer and intracellular trypsin in the lysate of 5 × 10 to 1 × 10 HCT116 cells per mL, respectively. The detection limit of trypsin is 0.6 ng mL in buffer or 359 cells per mL HCT116 cell lysate. The MnIO@pep-FITC is successfully employed to noninvasively monitor trypsin activity in the ultrasmall ( 4.9 mm in volume) BALB/c nude mouse-bearing HCT116 tumor by fluorescence imaging with external magnetic field assistance, demonstrating that it has excellent practicability.
在此，已提出一种荧光开启纳米传感器（MnIO@pep-FITC）用于检测胰蛋白酶活性，该传感器通过将胰蛋白酶的FITC修饰肽底物（pep-FITC）共价固定在锰掺杂的氧化铁纳米颗粒（MnIO NP）表面，并使用聚乙二醇（PEG）交联剂。pep-FITC与MnIO NPs的结合导致FITC荧光猝灭。胰蛋白酶切割后，FITC部分从MnIO NP表面释放，导致FITC荧光信号显著恢复。在最佳实验条件下，FITC荧光强度的恢复率分别与缓冲液中2至100 ng/mL范围内的胰蛋白酶浓度以及每毫升5×10至1×10 HCT116细胞裂解物中的细胞内胰蛋白酶浓度呈线性相关。胰蛋白酶在缓冲液中的检测限为0.6 ng/mL，或在每毫升HCT116细胞裂解物中为359个细胞。MnIO@pep-FITC通过外部磁场辅助荧光成像成功用于无创监测超小（体积为4.9 mm）携带HCT116肿瘤的BALB/c裸鼠体内的胰蛋白酶活性，证明其具有出色的实用性。
