The 20-year-old, who came to the City Ground with much potential from Bayern Munich, has failed to feature since the arrival of Joe Kinnear.
Kinnear told the Nottingham Evening Post: "I have made him available for anyone to have a look at on loan.
"But he has still got two years on his contract so, if anyone wants to take him permanently, I will be looking for a fee."
He has spent most of the season playing for the reserves but Hamburg are giving him a trial in a friendly match.