The Twinkle Factory launches tfCarmine for near-infrared

Dec 23, 2024 | FAST and splitFAST, Fluorogens, The Twinkle Factory

nirFAST and tfCarmine

nirFAST and tfCarmine

The Twinkle Factory launches tfCarmine for near-infrared labeling of proteins.  The new commercial fluorogen, tfCarmine, forms a bright near-infrared assembly with nirFAST, a variant of the well-known FAST tag.  Emitting at 715 nm with a 79-nm Stokes shift, tfCarmine builds up on FAST legacy: instantaneous, reversible, oxygen-free.  nirFAST-tfCarmine is hence unique for deep tissue imaging and spectral multiplexing.

tfCarmine meets the growing-every-day demand for far-red fluorescent proteins.  They indeed allow imaging deeper in tissues:  ridding of autofluorescence, less light scattering and absorbance by endogenous molecules, reduced light toxicity is reduced in the far-red region.  And also, they expand the accessible spectral window more and more obstructed by optical biosensors and optogenetic tools.

tfCarmine originates from the research led by Prof. Arnaud Gautier.  The team gathers researchers from Sorbonne University, Institut Curie and PSL Research University.  As a result of their collaboration, they issued an insightful paper in Nat. Commun. 2025.  tfCarmine is therein referred to as HPAR-3,5DOM or (4-hydroxy-3,5-dimethoxy-phenyl)allylidene-rhodanine.  The paper discloses a novel far-red system, nirFAST and HPAR-3,5DOM, engineered from the original FAST tag and HBR-based fluorogens.  Gautier indeed designed HPAR-3,5DOM together with nirFAST, specifically for near-infrared labeling.  HPAR-3,5DOM is a membrane-permeant fluorogenic ligand which selectively binds nirFAST-tagged proteins.  HPAR-3,5DOM is almost non-fluorescent when free in solution.  But it strongly fluoresces at 715 nm when bound to nirFAST.   nirFAST and HPAR-3,5DOM allow for imaging proteins in mammalian cells, but also in zebrafish embryo/larvae and chicken embryo.  It works in solution, in living cells or in fixed cells.  The paper discloses a variety of application cases and a comparison with emiRFP670 and miRFP713.

Interestingly, the fluorogen tfPoppy released earlier by The Twinkle Factory is also compatible with nirFAST.  And it emits at 680 nm (instead of 670 nm with frFAST).

The Twinkle Factory sells tfCarmine (a.k.a. HPAR-3,5DOM) and tfPoppy (a.k.a. HPAR-3OM).

More reading on near-infrared and far-red labeling with The Twinkle Factory

Nat. Commun. 2025 – A tunable and versatile chemogenetic near infrared fluorescent reporter (the princeps article introducing nirFAST and tfCarmine)

chemRxiv 2025 – Toward Far-red Emitting Chemogenetic Labelling for Live Cell Super-Resolution Microscopy using Fluorescence-Activating and Absorption-Shifting Tag (disclosing frFAST and tfPoppy for STED super-resolution microscopy)

Angew. Chem. Int. Ed. 2020 – A far-red fluorescent chemogenetic reporter for in vivo molecular imaging (the princeps article introducing frFAST and tfPoppy)