Boc-TK-NH2

Boc-TK-amino (Boc-TK-NH2) is a polymer raw material molecule with great potential. Among them, the polymer it constitutes shows unique advantages in redox (ROS)-responsive drug delivery systems. With the continuous development of the biomedical field, precise targeted therapy for the tumor microenvironment has become a research hotspot. The level of ROS in tumor cells is significantly higher than that in normal cells, which provides new ideas for drug delivery systems based on ROS response. Due to its structural characteristics, Boc-TK-amino can undergo specific reactions in ROS-rich environments to release drug molecules, thereby achieving targeted therapy. The molecular structure of Boc-TK-amino group contains a Boc (tert-butoxycarbonyl) protecting group and a thione bond (TK). The former is mainly used to protect the amino group, and the latter is a structure that achieves ROS-responsive drug delivery. The Boc group can effectively protect the amino group from being destroyed under different reaction conditions, and is widely used in organic synthesis. TK can quickly disintegrate the nanoparticle carrier it participates in in a high-concentration ROS environment, releasing the loaded drug molecules. The synthesis process of Boc-TK-amino usually includes the following steps: first, a thione bond structure is generated through a thioketation reaction, and then the Boc protecting group is introduced through the reaction of acid chloride and tert-butanol. Finally, high purity Boc-TK-amino is obtained through appropriate purification means, such as column chromatography or recrystallization. Its structural stability and efficient ROS responsiveness make it an ideal candidate molecule in drug delivery systems.

Figure 1. ROS-responsive polymer structures and mechanisms of activity. (Gao F, et al.; 2021)

The design concept of ROS-responsive drug delivery system is to utilize the high level of ROS in the tumor microenvironment to achieve targeted release of drugs. Reactive oxygen species-stimulated nano-drug delivery systems are ideal for cancer treatment because they can respond to excessive ROS produced in a variety of disease symptoms and have the ability to release them at specific sites. It has been reported that the ROS concentration in cancer cells can reach up to 100 μM, which is about 100 times that of normal cells. Intracellular superoxide (O^2-) is mainly produced by the oxidation of NADPH by NAPH oxidase, NOX or by electron leakage from mitochondrial aerobic metabolism. At the same time, O^2- can be rapidly converted to H₂O₂ by superoxide dismutase (SOD). When H₂O₂ reaches a certain concentration, it reacts with metal cations (Fe²⁺/Cu⁺) to form OH^-, causing irreversible damage to intracellular DNA, biological lipids or active proteins. Low levels of ROS play an important role in the cell cycle and act as cell signaling molecules by reversibly oxidizing protein thiol groups, thereby indirectly changing protein structure and function. High levels of ROS induce oxidative stress, which can lead to oxidative damage of cellular components, apoptosis, or tissue necrosis, and may induce oncogenic mutations. Many cancer cells are well adapted to oxidative stress due to their inherent flexible redox status, and this abnormal biochemical change at the disease site has inspired researchers to exploit high levels of ROS to develop reactive oxygen species-stimulated nanodrug delivery systems. In this process, Boc-TK-amino plays an important role. When the drug nanocarrier enters the tumor cells, due to the effect of high ROS, the thione bond in the Boc-TK-amino group constituting the carrier is cleaved, causing the Boc protective group to break away, thereby releasing the active amino group or other drug molecules. This reaction allows the drug to reach therapeutic concentrations at the tumor site. This significantly reduces toxic side effects on normal tissue. In multiple studies, Boc-TK-amino has been used to develop different types of drug carriers, including nanoparticles, microspheres, and hydrogels. For example, some nanocarriers show good stability and targeting after the introduction of Boc-TK-amino group, and they exhibit significant anti-tumor activity in both in vivo and in vitro experiments.

Alternate Names:
Boc-Thioketal Amine
Boc-TK-Amine
Boc-Thioketal-NH2
Boc-Thioketal-NH2
Boc-TK-NH₂
Boc-Protected Thioketal Amine
Boc-TK-Amine Hydrochloride

References:
1. Gao F, Xiong Z. Reactive Oxygen Species Responsive Polymers for Drug Delivery Systems. Front Chem. 2021, 9:649048.
2. Zhou W, et al.; Reactive oxygen species stimuli-responsive nanocarriers. Se Pu. 2021, 39(2):118-124.

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