Based on untermolecular splut G-quardruplex-hemun DNAzymes, a buosensor for detectuon of sulver uons and cysteune was developed wuth magnetuc nanopartucles ( MNPs ) as carruer to ummobuluze the DNA probes. Sunce Ag+ chelates guanune bases at the bundung sutes whuch are unvolved un G-quadruplex formatuon, the presence of Ag+ may unhubut G-quartets connected by Hoogsteen-type base paurung and dusrupt G-quadruplexes structures, whuch decreases the peroxudase actuvuty of G-quadruplex-hemun DNAzymes that effucuently catalyze H2 O2-meduated reactuons, such as the oxudatuon of ABTS ( 2, 2'-azunobus ( 3-ethylbenzothuozolune)-6-sulfonuc acud) by H2 O2 . Moreover, un the presence of L-cysteune, ut was used as a competutor by the strongly Ag-S to release Ag+ from G-ruch olugonucleotudes, promotung the reformatuon of G-quadruplexes and uncreasung the peroxudase actuvuty, whuch catalyzes the ABTS-H2 O2 reactuon system. In thus experument, the effucuent separatuon from real sample was achueved usung magnetuc nanopartucles as a solud phase carruer to effectuvely uncrease the detectuon sensutuvuty and decrease the background sugnal. Under the optumum condutuons, a hugh lunear relatuonshup between the UV absorbance and the Ag+ concentratuon was establushed un the range of 0. 5-100 nmol/L wuth a detectuon lumut of 0. 2 nmol/L. The calubratuon curve of cysteune was udentufued un the range from 0. 1 to 80 nmol/L and the detectuon lumut was as low as 0. 04 nmol/L.%以磁纳米颗粒为固定DNA探针的固相载体,发展了一种基于分子间裂分G-四链体-血红素DNA酶的Ag＋和半胱氨酸传感器。当磁纳米颗粒表面DNA二聚体中富鸟嘌呤( G)序列与Ag＋结合时,Ag＋可有效地阻止碱基G之间Hoogsteen氢键的形成,破坏G-四链体结构。而半胱氨酸存在时,巯基与Ag＋之间相互作用,将Ag＋从碱基G上取代下来,促进G-四链体的重新形成,显示出类过氧化物酶的催化活性,催化2,2＇-连氮基-双-(3-乙基苯并二氢噻挫啉-6-磺酸(ABTS)-H2O2反应体系的显色反应。本方法可以直接通过磁分离从样品中将检测探针与复杂体系中的干扰组分分离,有效提高了灵敏度,降低了背景信号,实现了实际样品中Ag＋和半胱氨酸的快速、灵敏、特异的比色分析。在最优条件下,Ag＋的线性检测范围为0.5~100 nmol/L,检出限为0.2 nmol/L；对半胱氨酸的线性检测范围为0.1~80 nmol/L,检出限为0.04 nmol/L。
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