there are a few things to consider. everyone who meets one of 2 requirements is entitled to unsubsidized stafford loans.
1. enrolled in a GRADUATE program
2. over the age of 24
if you're doing the post bac program to fulfill your basic science pre reqs, then its considered undergrad, and youre only entitled to subsidized stafford loans. The problem is that a lot of people, such as myself, reached to cap on their subsidized stafford loans while in undergrad, so this isn't an option. you need to find out if you reached your cap. If you're over the age of 24, you 're finally considered an adult by the federal government, and you're entitled to unsubsidized loans regardless if you have a graduate or undergraduate status. I was in a similar situation where I was 22, too young to get the unsubsidized loans, and had reach my subsidized cap while in undergrad. Luckily I has taken my pre med reqs and found a graduate program so I got the loans. ANyway, I think it still works like this.
If you look into all these options and still can't find a solution, there are alternative student loan companies like sallie mae that offer unsubsidized loans with low intrest rates. you need pristine credit or a co signer. hope this helps, if you have more questions you can PM me.