Diatom Frustule Array for Flow-Through Enhancement of Fluorescent Signal in a Microfluidic Chip

Zhenhu Wang,Jun Cai,De Gong

doi:10.3390/mi12091017

Abstract

Diatom frustules are a type of natural biomaterials that feature regular shape and intricate hierarchical micro/nano structures. They have shown excellent performance in biosensing, yet few studies have been performed on flow-through detection. In this study, diatom frustules were patterned into step-through holes and bonded with silicon substrate to form an open-ended filtration array. Then they were fixed into a microfluidic chip with a smartphone-based POCT. Human IgG and FITC-labeled goat–anti-human IgG were adopted to investigate the adsorption enhancement when analyte flowed through diatom frustules. The results indicated up to 16-fold enhancement of fluorescent signal sensitivity for the flow-through mode compared with flow-over mode, at a low concentration of 10.0 μg/mL. Moreover, the maximum flow rate reached 2.0 μL/s, which resulted in a significant decrease in the testing time in POCT. The adsorption simulation results of diatom array embedded in the microchannel shows good agreement with experimental results, which further proves the filtration enrichment effect of the diatom array. The methods put forward in this study may open a new window for the application of diatom frustules in biosensing platforms.

Highlights

The frustules regarded as bowl-shaped micro-sieves, where three layers of pores are regularly synthecould be regarded as bowl-shaped micro-sieves, where three layers of pores are regularly sized by diatom cells from concave surface to the convex surface, synthesized by diatom cellsthe from the concave surface to the convex surface,with withdiameters diameters of ~1 μm, nm, and nm, respectively, as shown in
There was no significant difference in the adsorption rate at a low flow velocity, such as less than 200 mm/s, as shown in Figure 8c, which was consistent with the smartphone processing data
Conclusions tules into an array pattern precisely with a micromanipulator, followed by bonding frusthis study, a template step-through holes was etched to arrange diatom tules to silicon substrate Inwith hot-melt glue, with aimed at improving fluorescence intensity frustules into an array pattern precisely with a micromanipulator, followed by bonding under the enrichment effect of porous biomaterial diatom frustules

Summary

Introduction

A type of nanostructured biomaterials synthesized by diatoms, are famous for their hierarchical regular pores structure composed of amorphous silica Their delicate structures and composition have drawn considerable attention in recent decades, and are verified to endow diatom frustules with excellent properties, such as outstanding mechanical strength [1], high specific surface ratio [2,3], biocompatibility [4,5], and transparency. They are petri-dish shaped with three layers of pores, of which the diameters range from 40 nm to 1 μm Their frustule valves can be regarded as “micro-sieves”, when similar artificial porous membranes are often used for the filtration and separation process. From that point of view, diatom frustules have an optimized filtration and separation membrane, which shows great potential in microfluidic systems

Methods

Results

Conclusion