There are a lot of blockchain conferences and events where private investors and venture capitals are available. There you can give information and pitch your project. An example of one of this events is Rethink Trust.: https://rethinktrust.org/

If you really have good project especially you already have a start up big investor will comes to you. And if you really seriouse about your project. You need to attend to every blockchain event and describe your project to community. When you gain trust from community its easy to get private investor with big money. But please dont scam or you will goea to jail. Your project must be reasonable.