Optical Platform to Analyze a Model Drug-Loading and Releasing Profile Based on Nanoporous Anodic Alumina Gradient Index Filters

Abstract

In this work, a methodology that exploits the optical properties of the nanoporous anodic alumina gradient index filters (NAA-GIFs) has been developed and applied to evaluate in real time the release dynamics of a cargo molecule, acting as a model drug, filling the pores. NAA-GIFs with two photonic stopbands (PSBs) were prepared with one of its stop bands in the same absorption wavelength range of the cargo molecule, whereas the second stopband away from this absorption range. Numerical simulation and experiments confirm that the relative height of the high reflectance bands in the reflectance spectra of NAA-GIFs filled with the drug can be related to the relative amount of drug filling the pores. This property has been applied in a flow cell setup to measure in real-time the release dynamics of NAA-GIFs with the inner pore surface modified by layer-by-layer deposition of polyelectrolytes and loaded with the cargo molecule. The methodology developed in this work acts as a tool for the study of drug delivery from porous nanostructures.

Real-Time Monitoring of Doxorubicin Release from Hybrid Nanoporous Anodic Alumina Structures

“…The analysis carried out in our previous study consisting of NAA-GIFs with two PSBs allows for obtaining the correlation between the height of the PSB and the amount of filling species within the structure [ 43 ]. In this work, we have designed a structure where the top part consists of GIF while the bottom part contains spectrum intensity.…”

“…It has been noticed with the previous experiments that the etching of the aluminium from the backside helps in improving the contrast of the PSB in the reflectance spectrum and also allows to see the interferometric color with the naked eye [ 43 ]. Therefore, the aluminium layer at the bottom was etched in a solution of HCl (100 mL in 400 mL H 2 O) and CuCl 2 (13.6 g added to the HCl/H 2 O mixture).…”

“…As mentioned in the introduction, this paper utilizes DOX to study the release kinetics in real-time. Inspired by the results obtained in our previous paper, which describes the in-depth filling pattern of a model drug (Rhodamine 6G) inside the NAA-GIFs structure, having two PSBs [ 43 ] that relate to the amount of drug filling the pores. In this study, we follow the same protocol for an effective filling and measurement of DOX with UV-VIS.…”

“…The same setup was also used to measure the drug loading inside the pores. The detailed instrumentation about the flow cell setup has been described in here [ 43 ]. In brief, the reflectance spectra of Hy-NAA-GIFs were registered with a light source (halogen) and a USB 2000+ fiber spectrometer (Ocean Optics, Orlando, FL, USA).…”

Development and Optimization of Experimental Biosensing Protocols Using Porous Optical Transducers

“…Nanoporous alumina is another material with similar features to pSi that has arisen interest for the development of biosensors. Indeed, several biosensors are developed using this material [46,47], as well as supports for the study of drug delivery [48].…”