Abstract: The present invention generally relates to micro- and nanoneedles, e.g., for use in penetrating plant cells, or other cells. In some embodiments, delivery of target biomolecules into cells with protective outer layers (e.g. plant cells or plant pollen), cells in seeds, or cells in tissues may be achieved. These outer layers could be native biological protections (e.g. complex exines for pollens), other types of cells, or general biological materials. In some cases, the needles are attached at an end on a surface. In some cases, pollen or seeds may have substantially thick and tough layers (intine and exine), which may render it more difficult to penetrate such materials, as compared with cell membranes, e.g., in mammalian cells.