Compare string alphabetically django db

I have a following model:

class Page(Model):
      book = ForeignKey(Book, on_delete=CASCADE)
      page = IntegerField()
      start = CharField(max_length=350, db_index=True)
      end = CharField(max_length=350, db_index=True)

How do I query DB in order to get pages that "contain" a given word?

page1 = Page.objects.create(start='beaver', end='brother')
page2 = Page.objects.create(start='boy', end='brother')

• Page.objects.filter("breast" between start and end) should return page1 and page2.
• Page.objects.filter("beast" between start and end) should return nothing.
• Page.objects.filter("block" between start and end) should return the only page1, since block is alphabetically after beaver and before brother.

Search should be case-insensitive.

So, I need to write a query that fetches all rows, where start is alphabetically "smaller" than the given word and end is alphabetically "larger" than the given word.

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