I would suggest you to give Gate entrance test once you are done with B.Tech in BioTech and get required score so that you can take admission in NITs and IITs. Apart from this, you can also try in private colleges as they may be accepting Gate score or conduct their own entrances so in case, you are interested in any private institute/college then kindly name it so that I can help you with the eligibility and admission process.

Good Luck!!!