Concept Herein, a combined Metal-organic Chemical Vapour Deposition - Chemical Bath Deposition approach has been used to grow ZnO nanorods on unpatterned and patterned substrates. Ordered two-dimensional arrays, obtained by colloidal lithography, have been proven to be effective to build up hybrid ZnO/SiO2 nanoplatforms in the perspective of development of advanced biosensor substrates. High surface area ZnO nanoplatforms were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was revealed that structure and thickness of ZnO buffer layers (deposited by MOCVD) strongly influence the CBD growth rate and, consequently, the final morphology and crystal texturing of ZnO nano-arrays. Moreover, the fluorescence recovery after photobleaching (FRAP) technique provides evidence that the protein mobility and fluorescence detection capability are tunable by proper patterning and morphological control of the hybrids ZnO based nanoplatforms. Motivations and Objectives Wet chemical approaches, being low cost, versatile and compatible with patterning techniques, are currently attracting considerable attention as bottom-up strategies to form one-dimensional ZnO nanostructures.1,2 In addition, colloidal lithography has been proven to be a flexible and cost-effective technique for the patterning of nanostructured arrays with long-range periodicity in a large scale.3 Recently, ZnO nanoplatforms have been investigated to study protein adsorption processes and have demonstrated a potential as fluorescence based sensor.4,5 Indeed, the green emission of the different hybrid ZnO nanostructures is significantly affected by the protein immobilization process. In this work, the interaction of the ZnO surfaces, deposited by MOCVD-CBD approach, with a model biomolecule (fluorescein-labeled albumin) was investigated by FRAP. Results and Discussion Using a successful integration of MOCVD, colloidal lithography and CBD techniques, large-area, highly ordered bimodal porous ZnO nanoplatforms were assembled (see Figure). Three different ZnO morphologies can be identified after the CBD growth: i) columnar seed layer; ii) nanotubes just below the PS colloids; iii) solid nanorods at the uncovered areas between adjacent spheres. Both patterned and unpatterned ZnO nanorods have been tested for model studies of protein mobility at the interface. The patterned layers, having a higher contribution of surface polar moieties than the corresponding unpatterned surfaces, exhibit a reduced lateral diffusion of the adsorbed protein. The gives an insight to the fabrication of tunable ZnO nanoplatforms having multiple morphologies and exceptionally high surface areas suitable for application in sensing devices. References [1] M.E. Fragalà, C. Satriano, G. Malandrino, Chem. Comm., 7 (2009) 839-841. [2] M.E. Fragalà, C. Satriano, Y. Aleeva, G. Malandrino, Thin Solid Films, 518 (2010) 4484-4488. [3] S.-M. Yang, S.G. Jang, D.-G. Choi, S. Kim, H.K. Yu, Small, 2 (2006) 458-475. [4] Dorfman, N. Kumar, J.I. Hahm, Langmuir, 22 (2006) 4890-4895. [5] M.E.Fragalà, C. Satriano, J. Nanosci. Nanotechn., 10 (2010) 5889-5893.

ZnO nano-platforms for fluorescence based biosensing

FRAGALA', Maria Elena;SATRIANO, Cristina
2011-01-01

Abstract

Concept Herein, a combined Metal-organic Chemical Vapour Deposition - Chemical Bath Deposition approach has been used to grow ZnO nanorods on unpatterned and patterned substrates. Ordered two-dimensional arrays, obtained by colloidal lithography, have been proven to be effective to build up hybrid ZnO/SiO2 nanoplatforms in the perspective of development of advanced biosensor substrates. High surface area ZnO nanoplatforms were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was revealed that structure and thickness of ZnO buffer layers (deposited by MOCVD) strongly influence the CBD growth rate and, consequently, the final morphology and crystal texturing of ZnO nano-arrays. Moreover, the fluorescence recovery after photobleaching (FRAP) technique provides evidence that the protein mobility and fluorescence detection capability are tunable by proper patterning and morphological control of the hybrids ZnO based nanoplatforms. Motivations and Objectives Wet chemical approaches, being low cost, versatile and compatible with patterning techniques, are currently attracting considerable attention as bottom-up strategies to form one-dimensional ZnO nanostructures.1,2 In addition, colloidal lithography has been proven to be a flexible and cost-effective technique for the patterning of nanostructured arrays with long-range periodicity in a large scale.3 Recently, ZnO nanoplatforms have been investigated to study protein adsorption processes and have demonstrated a potential as fluorescence based sensor.4,5 Indeed, the green emission of the different hybrid ZnO nanostructures is significantly affected by the protein immobilization process. In this work, the interaction of the ZnO surfaces, deposited by MOCVD-CBD approach, with a model biomolecule (fluorescein-labeled albumin) was investigated by FRAP. Results and Discussion Using a successful integration of MOCVD, colloidal lithography and CBD techniques, large-area, highly ordered bimodal porous ZnO nanoplatforms were assembled (see Figure). Three different ZnO morphologies can be identified after the CBD growth: i) columnar seed layer; ii) nanotubes just below the PS colloids; iii) solid nanorods at the uncovered areas between adjacent spheres. Both patterned and unpatterned ZnO nanorods have been tested for model studies of protein mobility at the interface. The patterned layers, having a higher contribution of surface polar moieties than the corresponding unpatterned surfaces, exhibit a reduced lateral diffusion of the adsorbed protein. The gives an insight to the fabrication of tunable ZnO nanoplatforms having multiple morphologies and exceptionally high surface areas suitable for application in sensing devices. References [1] M.E. Fragalà, C. Satriano, G. Malandrino, Chem. Comm., 7 (2009) 839-841. [2] M.E. Fragalà, C. Satriano, Y. Aleeva, G. Malandrino, Thin Solid Films, 518 (2010) 4484-4488. [3] S.-M. Yang, S.G. Jang, D.-G. Choi, S. Kim, H.K. Yu, Small, 2 (2006) 458-475. [4] Dorfman, N. Kumar, J.I. Hahm, Langmuir, 22 (2006) 4890-4895. [5] M.E.Fragalà, C. Satriano, J. Nanosci. Nanotechn., 10 (2010) 5889-5893.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/87748
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