Template‐Synthesized Vertical Needle Array as Injection Platform for Microalgae

Increasing numbers of studies in the past few decades have demonstrated vertically-oriented nanoneedles arrays (NNAs) as innovative tools to interrogate and manipulate biological cells, where the needles are inserted into the cells as functional probes for high-throughput detection and biomolecule delivery. However, majority of these studies use mammalian cells: leaving NNA application to plant cells still in its infancy and largely unexplored. This paper highlights our contributions in exploring the utility of NNAs to microalgae - a diverse group of aquatic, photosynthetic organisms studied intensively as bio-factories for producing high-value-added products such as fuels and pharmaceuticals. Microalgal strain development processes have long suffered from the hard cell wall that surrounds the cell and inhibits delivery of foreign materials into the cell. Conically-shaped, metallic NNAs were developed with template synthesis that successfully penetrate through the cell wall barrier and achieve material injection - using the widely studied model microalga, Chlamydomonas reinhardtii. Earlier works from mammalian cells are introduced and discussed to clarify the framework established in this field, while recent studies of both mammalian and microalgal cells are also referenced to examine the trends, challenges, and future perspectives of NNA application to microalgae.