Can I specify shards to database?

Hello.
Is any solution to specify shards for special database.

For example: I have 4 shards:

web0001:web0001:/server1,server2,server3
web0002:web0002:/server4,server5,server6

photo0001:photo0001:/server7,server8,server9
photo0002:photo0002:/server10,server11,server12

Can I assign database 'web' works only on web0001,web0002 shards and 'photo' database works on photo0001,photo0002 on one mongos instance and in one config?

Thank you.