FIB-milled plasmonic nanoapertures allow for long trapping times of individual proteins.We have developed a fabrication methodology for label-free optical trapping of individual nanobeads and proteins in inverted-bowtie-shaped plasmonic gold nanopores.  Arrays of these nanoapertures can be reliably produced using focused ion beam (FIB) milling with gap sizes of 10-20 nm, single-nanometer variation, and with a remarkable stability that allows for repeated use. 
FIB