Amine-Functionalized ZIF-8 as a Fluorescent Probe for Breath Volatile Organic Compound Biomarker Detection of Lung Cancer Patients

Abstract

The highly thermally and chemically stable imidazole framework ZIF-8 samples were separately postmodified with amine groups by using N,N′-dimethylethylenediamine (MMEN) and N,N-dimethylaminoethylamine (MAEA), which had the same molecular formula but different structures. The modified ZIF-8 samples (ZIF-8@amine) were thoroughly characterized, including powder X-ray diffractometry, Fourier-transformed infrared spectroscopy, and physical adsorption at 77 K by nitrogen, thermogravimetric analysis, and photophysical characterization. Results showed that after modification, the Brunauer–Emmett–Teller surface area and total pore volume both increased, almost one time higher than those of the original ZIF-8 sample, and followed the order: ZIF-8-MMEN > ZIF-8-MAEA > ZIF-8. Furthermore, the N–H group was successfully grafted into the modified ZIF-8 samples. To examine the sensing properties of the modified ZIF-8@amine samples toward the breath biomarkers of lung cancer, five potential volatile organic compound biomarkers were used as analytes. ZIF-8-MMEN and ZIF-8-MAEA revealed a unique capacity for sensing hexanal, ethylbenzene, and 1-propanol with high efficiency and sensitivity. The three samples all did not show sensing ability toward styrene and isoprene. In addition, ZIF-8, ZIF-8-MMEN, and ZIF-8-MAEA all can sense hexanal with a detection limit as low as 1 ppb.

ZIF-8 as a promising drug delivery system for benznidazole: development, characterization, in vitro dialysis release and cytotoxicity

“…The breathing flexing of the ZIF-8 framework is the process in which the movement/twisting of the imidazolate linkers in the network, providing a greater opening of the crystal pore windows, causing a dilation or contraction of the pores, directly interfering with the adsorbed load and in the diffusion of molecules. ZIF-8 presents the beginning of the dissociation of the coordination network in the pH range between 5.0 and 6.0, and intense erosion in an even more acidic pH, which can promote the network's "breathing", opening of spaces between the polymeric mesh and, consequently, intensifying the drug release which, in this case, can be modulated by changing the pH 37,38,47 .…”

Benznidazole in vitro dissolution release from a pH-sensitive drug delivery system using Zif-8 as a carrier

“…Due to the flexible structure ZIF-8 it is possible to observe movements of the organic ligands of the coordination network in acidic pH, which, in turn, open or close the pore windows of the ZIF-8 cavities and enabling the delivery or release of the drug. This phenomenon is best seen in a pH range between 5.0 and 6.0, because at more acidic pHs, ZIF-8 begins to suffer the erosion process that has already been mentioned [46,47].…”

Recent development of the fluorescence-based detection of volatile organic compounds: a mechanistic overview

“…47,48 Zhang and co-workers have demonstrated a post-synthetic modification strategy to modify ZIF-8 with N,N 0 -dimethylethylenediamine (MMEN) and N,N-dimethylaminoethylamine (MAEA) as the functional groups for the fluorescence detection of lung cancer VOC biomarkers. 49 These ZIF-8-MMEN and ZIF-8-MAEA revealed a unique capacity for the sensing of lung cancer biomarkers like hexanal, ethylbenzene, and 1-propanol with high efficiency and sensitivity. OFs have been extensively explored and much success has been achieved in developing fluorescent probes.…”