Amidelinked

Amidelinked is an adjective used in chemistry and bioconjugation to describe a molecule in which two components are joined by an amide bond. An amide linkage is formed between a carboxyl-derived carbonyl group and an amine, resulting in a bond written as -CO-NH-. In amidelinked compounds, this linkage connects fragments such as amino acids, peptides, drugs, dyes, or polymer segments. The term is often used interchangeably with amide-linked or peptide-linked when the connection is through an amide bond.

In nature, the backbone of proteins consists of amidelinked chains of amino acids connected by peptide (amide) bonds. In synthetic contexts, amidelinked structures are common in bioconjugation, drug delivery, and materials science, where a functional payload or label is tethered to another molecule via an amide bond. Synthesis typically involves activating a carboxyl group and coupling it to a free amine, using reagents such as carbodiimides (for example EDC or DCC) with additives or via activated esters and acid chlorides.

Amide bonds are relatively stable under physiological conditions, contributing to the persistence of amidelinked assemblies. They can be cleaved by proteases or amidases in biological environments, or by specific chemical or enzymatic triggers designed for controlled release in engineered systems.

Applications of amidelinked constructs include peptide therapeutics, antibody–drug conjugates, fluorescent or diagnostic probes, and polymer conjugates, where a stable yet potentially cleavable linkage is advantageous for function and delivery.