Breast cancer is the most common disease among women and the second most common disease worldwide, accounting for 2.09 million new cases of cancer diagnosis in 2018. It accounts for 11.6% of all cancer cases and is the leading cause of cancer mortality for women as well as the fourth cause of cancer death overall. HER2-positive breast cancer is distinguished as a distinct subtype of breast cancer by the overexpression of HER2, a specific protein found on the surface of cancer cells. Because targeted medicines precisely target the overexpression of the HER2 protein, the management of HER2-positive breast cancer has undergone a complete revolution. Monoclonal antibodies targeting the extracellular domain of the HER2 protein were regarded to be a step forward in the treatment of breast cancer; however, affibody-DNA nanoparticles in particular offer a paradigm-shifting picture of cancer treatment and diagnostics. The advantages of affibody DNA nanoparticles include targeted distribution, customization, small size, potential for combination therapy, and unique character. These attributes make them a promising alternative to monoclonal antibodies, the current standard therapy, in the treatment of HER2 positive breast cancer. The purpose of this paper is to provide information on the most promising recently developed nanoparticle-based therapies for the diagnosis and management of HER-2-positive breast cancer.

Due to a continued interest in the fundamental properties of dihydrofolate reductase (DHFR) and its enzymatic activities, this study employed the use of six fluorescent tryptophan derivatives, for single site amino acid replacements. The two positions 30 and 47 within DHFR were studied to discover the rate at which these larger tryptophan analogues may be incorporated. Additionally, it was to be determined how much activity the mutated DHFR’s could retain when compared to their wild type counterpart. Through a review of literature, it was shown that previous studies have illustrated successful incorporation and toleration of unnatural amino acids.
Each of the six analogues A through F were relatively efficiently incorporated into the enzyme and well tolerated. Each maintained at least a third of their catalytic activity, measured through the consumption of β-nicotinamide adenine dinucleotide phosphate. Primarily, derivatives B, C, and D were able to retain the highest amount of activity in each position; B and D were the most tolerated in positions 30 and 47 with respective values of 68 ± 6.1 and 80 ± 12. The findings in this study illustrate that single tryptophan derivatives are able to be incorporated into Escherichia coli DHFR while still allowing the maintenance of a significant portion of its enzymatic activity.