Chemicals & Small Molecules

9-Oxoheptadecanedioic acid

Azido-PEG4-Val-Ala-PAB-Exatecan serves as a cathepsin-cleavable Val-Ala dipeptide conjugated to an exatecan payload, a structural analog of camptothecin. The terminal azido partakes in click chemistry reactions with DBCO, BCN, and linear alkynes.

Azido-PEG4-Val-Ala-PAB-SN38 serves as a cleavable ADC linker featuring a cleavable Val-Cit dipeptide, a PAB group, and an SN38 warhead. The PEG linker improves the solubility of the compound. The azide moiety can perform click chemistry reactions with BCN, DBCO, and linear alkynes.

FAM Phosphoramidite, 6-isomer (hydroxyprolinol) serves as a versatile reagent for 5’ and internal labeling of oligonucleotides. It facilitates the synthesis of fluorescein-labeled strands. The 6-aminohexanoate linkage acts as a spacer between the nucleotide skeleton and the functional group. Additionally, this reagent features a dimethoxythrityl protection group, enabling purification via reversed-phase HPLC or cartridge methods.

TCO Phosphoramidite C6 acts as a versatile reagent for TCO-modified oligonucleotides, introducing a TCO moiety into substrates with primary or secondary hydroxyl groups. Trans-cyclooctene readily reacts with tetrazines via inverse electron-demand Diels-Alder cycloaddition (IEDDA). The resulting TCO-Tetrazine ligation offers ultrafast kinetics, selectivity, and long-term stability in aqueous media, making it valuable for low-concentration applications like protein-protein conjugations.

DAPI (hydrochloride) is a blue-emitting fluorescent dye that strongly binds to adenine-thymine-rich regions in DNA. Widely used in fluorescence microscopy and flow cytometry, DAPI serves as a nuclear counterstain. When bound to double-stranded DNA, DAPI exhibits ~20-fold fluorescence enhancement, with an absorption peak at 358 nm and emission peak at 461 nm. It also binds to RNA, albeit with less intensity, causing its emission spectrum to shift to ~500 nm.

Hoechst 33258 is a blue-emitting fluorescent dye that selectively binds to adenine-thymine-rich regions in double-stranded DNA. Its fluorescence is enhanced by AT-rich DNA strands. With excitation/emission maxima at 351/463 nm, it exhibits a considerable Stokes shift. Although it can enter living cells, its permeability is lower than Hoechst 33342. Notably, Hoechst 33258 is less toxic than DAPI, ensuring better cell viability.

Hoechst 33342 is a blue-emitting fluorescent dye which selectively binds to adenine-thymine-rich regions in double-stranded DNA. With excitation/emission maxima at 351/461 nm, it exhibits a considerable Stokes shift. Notably, Hoechst 33342 is less toxic than DAPI, ensuring better cell viability. It is widely used in fluorescence microscopy and flow cytometry for staining chromosomes and nuclei in live and fixed cells, particularly to distinguish condensed pycnotic nuclei in apoptotic cells and for cell sorting.

Hoechst 34580 serves as a blue-emitting fluorescent dye that selectively binds to adenine-thymine-rich regions in double-stranded DNA. It exhibits excitation/emission peaks at 380/438 nm when bound to DNA, with fluorescence intensity sensitive to solvent pH. Unbound dye emits green light in the 510–540 nm range, more pronounced at higher concentrations or inadequate washing. While capable of penetrating living cells, it is less permeable than Hoechst 33342. Importantly, the dye is less toxic than DAPI, ensuring better cell viability post-staining.