Two dual-functional Zn-MOFs with fluorescent sensing of biomarker 3-nitrotyrosine and proton conduction

The construction of dual-functional metal-organic frameworks (MOFs) with fluorescent sensing and proton conduction is always challenging and attractive. This work successfully designed and synthesized two dual-functional Zn-based MOFs , [Zn 2 (L)(μ 3 –OH)(DMF)] ( Zn-MOF-1 ) and [Zn(HL)(4,4′-bipy)]·DMF·H 2 O ( Zn-MOF-2 ), (H 3 L = 5-(3-(carboxyl)-benzylamino)-isophthalic acid; 4,4′-bipy = 4,4′-bipyridine; DMF = N,N -dimethylformamide) under solvothermal condition. Based on the excellent stability and fluorescent characteristic of compounds, the two fluorescent probes realize the sensing of 3-nitrotyrosine (3-NT) as a biomarker of oxidative damage with good selectivity, high sensitivity and low limits of detection. More importantly, Zn-MOF-1 and Zn-MOF-2 firstly realize the sensing of 3-NT in the real human plasma with satisfactory recoveries of 97.94 %∼111.71 % and 91.99 %∼103.04 %, respectively. The construction of portable test paper with the obvious color change broadens the practical application. Furthermore, the smartphone-assisted platform is used to the detection of 3-NT, thereby facilitating the advancement of diagnostic methods for related diseases. In addition, the proton conductivities of Zn-MOF-1 and Zn-MOF-2 can reach up to 3.80×10 −4 S·cm −1 and 4.74×10 −6 S·cm −1 under 368 K and 95 % relative humidity (RH) with the considerable time stability, respectively. Meanwhile, the relationship between the structure and property is also studied. This work provides a foundation for the construction of dual-functional MOFs with fluorescent sensing and proton conduction.