Conjugates are provided containing a graphene quantum dot, a targeting moiety, and an active agent. The conjugates can be used to provide one or more therapeutic, prophylactic, or diagnostic effects to a subject in need thereof. The subject can be a cancer patient and the active agent an anti-cancer agent. The graphene quantum dots can have an average particle size of about 1-20 nm and a monodisperse size distribution. The size distribution can have a span about 1 or less and/or a coefficient of variance of about 0.5 or less. Methods of making the conjugates are provided. The methods can include conjugating the targeting moiety to the GQD using a reactive coupling group. Methods of treating, preventing, and/or diagnosing a disease or disorder in a patient in need thereof by administering the conjugates are provided.
