A Brief Guide to Bioconjugation
Posted: Oct 25, 2017
Theoretically speaking, nearly all compounds, whether natural or synthetic, can be chemically combined to create new characteristics as desired by their creators, without compromising too much to their individual features.
What is bioconjugation?
Bioconjugation, as its name suggests, is a technique to form a stable covalent link between at least two different molecular parts of biological origin. Bioconjugates used in organisms or cells are designed this way so that they are water soluble or that cells are able to compartmentalize them.
What sense does bioconjugation make?
As time went on, researchers have gained an increasing understanding of biomolecules, making it possible to apply biomolecules into numerous fields like medicine and materials. You may wonder why scientists endeavor so much for personalizing new biomolecules, and here is the reason. Biomolecules, when artificially and technically modified, can take on diverse characteristics and thus serving different functions, like
a. tracking cellular events;
b. revealing enzyme function;
c. determining protein biodistribution;
d. imaging specific biomarkers;
e. delivering drugs to targeted cells
(Just to name a few)
And, bioconjugation is a crucial strategy that scientists employ to link these modified biomolecules with different substrates.
What are the types of bioconjugation?
Based on the level of difficulty of synthesis, bioconjugation can be roughly classified into the following categories. One is the most common bioconjugation synthesis, such as the coupling of a small molecule (for example, a biotin, a protein or a fluorescent dye), or the coupling of an antibody to an enzyme. Of course, there are less commonly seen molecules also used in bioconjugation like carbon nanotubes.
Apart from what are mentioned above, antibody-drug conjugate (or briefly referred to as ADC) also belongs to one type of bioconjugation, with Brentuximab vedotin and Gemtuzumab ozogamicin being its fine examples. Recently ADCs are getting more active as a research topic in the pharmaceutical industry. More attention has been focused on exploring targeted therapy for cancer treatment such as peptide drug bioconjugation. Also, ADCs are closely involved with nanotechnology applications such as bioconjugated quantum dots in recent decade.
What challenges still facing bioconjugation?
Be it the simple use of a fluorescent dye marker or the complex design of antibody drug conjugates, it’s no easy task for the employment of bioconjugation. As a matter of fact, synthesis of bioconjugates faces a variety of challenges, both known and unknown, including but not limited to the following:
a. enhancing specificity and stability;
b. improving bioavailability;
c. reducing toxicity of carrier molecules.
However difficult, bioconjugation is still by far the most constructive technique for target-based treatment for curing a string of diseases such as cancer, etc., according to scholar Hermanson.
Most importantly, we should first identify the principle target group on the biomolecules and then match them with the appropriate reactive groups for conjugation. At the same time, researchers should also watch carefully any potential side reactions or competing hydrolysis that may occur, and any interfering substances that should be avoided. To sum up, the prerequisite for success of bioconjugation is a solid understanding of these reactions and hence shedding some light on how to optimize them in order to create the best possible bioconjugates for the intended downstream applications.
There is still a long way to go. No doubt for that.
The author is a true follower of biochemistry. BOC Sciences, the company he works for, is a trustworthy supplier of inhibitors.