Thursday, February 1, 2018

DBCO or Azide reactive liposomes (Click chemistry)

For the past 50 years various types of chemistries have been used for conjugation of molecules such as antibodies, peptides, proteins or other reactive ligands to the surface of liposomes. In general the conjugation can be achieved through the N-terminus, the C-terminus or the available sulfur (Fab’ fraction or thiolated antibodies). Not all chemistries have the same yield and efficiency of conjugation and often reproducing biocompatible batches can be a challenge.
Copper-free click chemistry is a fairly new chemistry that has been commercialized during the past few years. More and more click chemistry based reagents are becoming available commercially which makes the formulation development much easier for scientists. The great advantage of this chemistry is biocompatibility since no cytotoxic copper catalyst is required.
By far, click chemistry is the most efficient and easiest conjugation chemistry available for coupling of antibodies and other reactive ligands to the surface of the liposomes. The conjugation chemistry is based on the reaction of the dibenzocyclooctyne (DBCO) reagent with an azide linker to form a stable triazole. DBCO moiety can be on the antibody and azide moiety can be on liposomes and vice versa.

Wednesday, January 21, 2015

Antibody structure and Fragments

This is an educational video that shows the antibody structure and fragments that are made during digestion with various enzymes such as Pepsin, Papain and Ficin. If you need to conjugated your antibody through available free sulfur to the reactive group on the surface of the liposomes such as Maleimide, PDP, MCC or MPB then the antibody has to be digested and the disulfide bridge should be broken by using reducing agents such as DTT.

The video also shows various methods for making antibody fragments that are suitable for conjugation through N-terminus or C-terminus.


Monday, January 19, 2015

Liposome size calculation

The animation below only applies to unilamellar liposomes.