Metal-assisted chemical etching (MACE) affords porous silicon nanostructures control over size, shape, and porosity in a single step. Simplicity and flexibility are potential advantages over more traditional silicon bulk micromachining techniques. MACE-generated porous micro- and nanostructures are suitable as biomaterials through their length scales and biocompatibility.

This work provides a comprehensive overview of the MACE reaction mechanism that yields biomedically relevant silicon nanostructures – from nanowires, nanopillars, to sub-micrometer holes and pores. We discuss their biomedical applications in biosensors, cell capture and transfection arrays, and drug delivery vectors. We assess the reported benefits of the various nanostructures and discuss whether MACE provides clear and distinct advantages over other techniques.

The flexibility and simplicity of MACE comes at a cost. The reaction parameters are many and inter-related, and we lack a full model of the etching mechanism. While the cathode reaction is well understood, the anode reaction involving dissolution of the silicon remains controversial. Such uncertainties impede rational design of specific structures that address biomedical requirements. We summarize current understanding to provide design guidelines for structures used in biomedicine and review the effects of key parameters on the morphological attributes of the etched features.

金属辅助化学蚀刻 (MACE) 可在单个步骤中提供多孔硅纳米结构对尺寸、形状和孔隙率的控制。与更传统的硅体微加工技术相比，简单性和灵活性是潜在优势。MACE 生成的多孔微纳米结构因其长度尺度和生物相容性而适合作为生物材料。

这项工作全面概述了 MACE 反应机制，该机制产生了与生物医学相关的硅纳米结构——从纳米线、纳米柱到亚微米孔和孔隙。我们讨论了它们在生物传感器、细胞捕获和转染阵列以及药物递送载体中的生物医学应用。我们评估了所报告的各种纳米结构的好处，并讨论了 MACE 是否比其他技术具有明显和独特的优势。

MACE 的灵活性和简单性是有代价的。反应参数很多且相互关联，我们缺乏蚀刻机制的完整模型。虽然阴极反应很好理解，但涉及硅溶解的阳极反应仍然存在争议。这种不确定性阻碍了满足生物医学要求的特定结构的合理设计。我们总结了当前的理解，为生物医学中使用的结构提供设计指南，并审查关键参数对蚀刻特征的形态属性的影响。