Boundedness is not a topological concept. For example, take [itex]\mathbb{R}[/itex], then this is not bounded for the metric [itex]d(x,y)=|x-y|[/itex], but it is bounded for the metric [itex]d(x,y)=|atan(x)-atan(y)|[/itex]. However, the two spaces are homeomorphic.
So it's possible that two metric spaces carry a homeomorphic topology, but that one is bounded and the other is not.
This is why boundedness is not studied in topology.