Evolution of zinc oxide nanostructures through kinetics control

Abstract

In-depth understanding of the kinetics of the vapor deposition process is substantial for advancing this capable bottom-up nanostructure synthesis approach into a versatile large-scale nanomanufacturing technology. In this paper, we report a systematic study of the vapor deposition kinetics of ZnO nanomaterials under controlled atmosphere and properly refined deposition conditions. The experiments clearly evidenced the self-catalyzed growth of ZnO NWs via the formation of ZnO nanoflowers. This result illustrated how ZnO morphologies were associated with the discrepancy between oxidation rate and condensation rate of Zn. The capability of switching the NW morphologies and possibly mechanisms was demonstrated by kinetically controlling the deposition system. The high Zn composition during the deposition resulted in strongly luminescent NWs, which can be used for optical imaging applications. This research discovered a fundamental kinetics that governs the mechanisms and morphology selection of nanostructures in a non-catalyst growth system.

Biomedical Applications of Zinc Oxide Nanomaterials

“…We recently synthesized green fluorescent ZnO nanowires (NWs), which could overcome the abovementioned hurdles, and demonstrated that the ZnO NWs can be employed for targeted imaging of cancer cells [44, 45]. The c(RGDyK) (abbreviated as RGD) peptide, which is a potent antagonist of integrin α v β 3 (a key protein involved in tumor angiogenesis and metastasis) [46, 47], was used as the targeting ligand.…”

Structural and optical properties of TZO thin films

“…The deposition of ZnO consists of two different procedures, condensation and oxidation of zinc. At high temperatures (>1000 C), the oxidation rate is very faster than condensation [17]. Comparison between condensation and oxidation rate at different temperatures can help us to explain the formation of different ZnO nanostructures.…”

Red Fluorescent Zinc Oxide Nanoparticle: A Novel Platform for Cancer Targeting

“…19 The fluorescent ZnO NPs coupled with PET imaging capacity can enable the in vivo monitoring of ZnO nanomaterials in biomedical applications. Compared with our previously developed green fluorescent ZnO nanowires, 20, 21 these red-fluorescing ZnO NPs possess better tissue penetration of the optical signal, making them more preferable for fluorescence-guided drug delivery purposes. However, the requirement of ultraviolet light excitation (excitation wavelength: ~350 nm) for their fluorescence limited their applications in vivo, which serves as the primary reason that no fluorescence imaging was performed in vivo in the current study.…”