Allophycocyanin (APC) | High-Purity Fluorescent Label for Flow Cytometry & Immunoassays

Exceptional Brightness in the Far-Red Channel APC's high molar extinction coefficient combined with a quantum yield of approximately 0.68 makes it one of the brightest naturally available far-red fluorescent labels. Its signal in the 660–680 nm emission range is well-separated from common blue-laser dyes (FITC, PE), enabling clean multicolor panel design without heavy compensation.

Minimal Autofluorescence Interference Biological samples — particularly cells and tissue sections — produce significant autofluorescence under blue laser excitation. APC is excited by red lasers (633/640 nm), a wavelength range where cellular autofluorescence is intrinsically very low. This makes APC particularly valuable for detecting low-abundance targets that would be obscured by background in other channels.

Large Stokes Shift for Clean Spectral Separation APC has a large gap between its excitation (~650 nm) and emission (~660 nm) peaks, reducing the risk of spectral overlap with the excitation source. Combined with its far-red emission, this makes APC an ideal complement to blue-laser fluorophores in multicolor cytometry panels.

Highly Water-Soluble and Easy to Conjugate APC is highly water-soluble and presents accessible surface lysine and cysteine residues, making it straightforward to conjugate to antibodies, streptavidin, and other proteins using standard crosslinker chemistry (e.g., SMCC, NHS esters). Its large size (~105 kDa) also makes it an efficient energy acceptor in FRET-based tandem dye configurations.

Broad Excitation Range Although optimally excited at 650 nm, APC can be excited across a broad range of red-wavelength laser lines including 594 nm, 633 nm, and 640 nm, providing flexibility across different instrument configurations.

Vertically Integrated from Algae Cultivation Flogen APC is purified from microalgae grown by FEBICO — one of the world's most experienced microalgae cultivation companies. This upstream control over biomass quality is the foundation of our lot-to-lot consistency and means you are never dependent on a third-party raw material supplier.

Strict QC Release Criteria Every lot is tested and released against defined spectral purity specifications (A651/A280 ≥ 5.0; A651/A620 ≥ 1.5) before shipment, with a COA available for every production batch.

Flow Cytometry, Antibody Conjugation APC is one of the most widely used fluorescent labels for antibody conjugation in flow cytometry. Its far-red emission (662 nm) is cleanly detected in the APC channel (typically a 660/20 nm bandpass filter) on instruments equipped with a red laser. Because APC is spectrally distinct from FITC (525 nm), PE (578 nm), and PerCP (677 nm on the blue laser), it is an essential building block of multicolor panels — enabling 4-, 5-, and 6-color configurations on instruments with blue and red lasers. Flogen APC is supplied at a purity suitable for antibody conjugation (A651/A280 ≥ 5.0), ensuring high conjugation efficiency with minimal non-fluorescent protein contamination.

Tandem Dye Production APC's favorable FRET donor-acceptor geometry and bright far-red emission make it the standard energy donor for APC-based tandem fluorophores, including APC-Cy5.5, APC-Cy7, and APC-R700. In these configurations, APC absorbs red laser energy and transfers it to the cyanine acceptor dye, shifting the effective emission into the near-infrared (700–800 nm) — extending the spectral range of a single red laser across multiple detection channels. Flogen APC is used as a raw material for tandem dye production by diagnostic reagent manufacturers.

Streptavidin Conjugate Production APC conjugated to streptavidin (SA-APC) provides a far-red reporter for biotin-based detection systems in flow cytometry, bead-based assays, and immunohistochemistry. Flogen's Streptavidin APC (Cat. No. 4SA) is manufactured using cl-APC (see below) for enhanced stability, but standard APC (RM3) is available for customers who prefer to perform their own conjugation.

Immunohistochemistry (IHC), Fluorescence APC's far-red emission is well-suited to fluorescence IHC workflows, particularly in multiplexed tissue staining where co-localization with nuclear counterstains (DAPI, ~461 nm) or green-channel markers (FITC/Alexa 488, ~525 nm) is required. The wide spectral separation between APC and these shorter-wavelength labels minimizes channel crosstalk and simplifies image analysis.

Fluorescence Immunoassays and Diagnostics APC is used as a reporter fluorophore in fluorescence-based immunoassay formats (FIA) for point-of-care and laboratory diagnostics, where its red-laser compatibility and low background autofluorescence contribute to high assay sensitivity