Earlier, there was a company using some kind of 'matrix' to mix with gRNA and Case9 protein (not DNA) to coat on gold particles for bombardment. So, they can shoot those proteins directly into plant cells, without worrying foreign gene integrating into its genome. They got a good result. But, when I asked what kind of 'matrix' they were using, they did not want to say. So, I would like to know that too.

OK, I found this paper (see below). This is the paper I was talking about in my previous answer. They called it "particle delivery matrix" (See Yellow highlights in Materials and Methods section). They are from DuPont Pioneer Company.

Also, see our (me and the author) discussion about this paper:

https://www.researchgate.net/publication/310474136_Genome_editing_in_maize_directed_by_CRISPR-Cas9_ribonucleoprotein_complexes

Article Genome editing in maize directed by CRISPR–Cas9 ribonucleopr...

there are a couple of references out there describing the coating of gold particles with cas9 protein-guideRNA complex. ours group was the first to publish this last year and the methods are in the paper. 

 Thank you so much Yuan-Yeu Yau  will go through the paper. 

 Thank you so much A. Mark Cigan, will go through the details, eventually I need something will get back to you.

Hi  A. Mark Cigan,

1. Yes, your group is the first to publish this. You are one of the authors in the paper I attached in my previous answer. But, in the Materials and Methods section of the paper, it did not mention what is the 'particle delivery matrix'. I guess this is the most important part of the whole procedure.

2. You mentioned that there are a few references for coating of gold particles with cas9 protein-guideRNA complex. Could you list the references. Thanks.

Have you seen this most recent published paper (2017 Jan) about bombardment of RNP complex into wheat genome. They followed the method published in: Martin-Ortigosa, S. & Wang, K. Proteolistics: a biolistic method for intracellular delivery of proteins. Transgenic Res. 23, 743–756 (2014).

See attached paper with yellow highlight.

It is quite challenging. And I agree with Yuan-Yeu Yau that the details are always missing in the papers. As far as I see it in my work is that simply mixing of Gold with RNPs by pipetting does work. When coating it works better when u dry them at 4°C. But even if u do everything very carefully it works in one shot and with the other not. To be honest the particle gun itself is one of the most shitty machines I ever used. Does someone now found some method which finally worked?