Bioconjugation is the process of coupling two biologically relevant molecules together with a covalent linkage. Almost all bioconjugations are facilitated with linkers, which are generally small organic molecules. These techniques have long provided a plethora of biologically useful reagents in various analytical applications such as tagging mechanisms, like the metal chelate mass/affinity tags, fluorescent markers for flow cytometry and microscopy, as well as therapeutic applications such as targeted drug delivery, nuclear magnetic imaging and nuclear medicine applications in oncology. These linkers are highly selective, stable in solution, not susceptible to non-specific binding in biological environment, with stable isolatable intermediates. They include small molecules, macrocyclic metal chelates and small cyclic peptides. These small linkers and cyclic peptides provide novel small molecule bioconjugation chemistries that use the thiol ester carbonyl to specifically react towards a lysine under biological conditions or through formation of disulfides. These new linkers are thought of such that they would all serve as infinite affinity binders.