title: Bioconjugatable, PEGylated Hydroporphyrins for Photochemistry and Photomedicine. Narrow-Band, Near-Infrared-Emitting Bacteriochlorins.
abstract: Synthetic bacteriochlorins absorb in the near-infrared (NIR) region and are versatile analogues of natural bacteriochlorophylls. The utilization of these chromophores in energy sciences and photomedicine requires the ability to tailor their physicochemical properties, including the incorporation of units to impart water solubility. Herein, we report the synthesis, from two common bacteriochlorin building blocks, of five wavelength-tunable, bioconjugatable and water-soluble bacteriochlorins along with two non-bioconjugatable benchmarks. Each bacteriochlorin bears short polyethylene glycol (PEG) units as the water-solubilizing motif. The PEG groups are located at the 3,5-positions of aryl groups at the pyrrolic β-positions to suppress aggregation in aqueous media. A handle containing a single carboxylic acid is incorporated to allow bioconjugation. The seven water-soluble bacteriochlorins in water display Qyabsorption into the NIR range (679-819 nm), sharp emission (21-36 nm full-width-at-half-maximum) and modest fluorescence quantum yield (0.017-0.13). Each bacteriochlorin is neutral (non-ionic) yet soluble in organic (e.g., CH2Cl2, DMF) and aqueous solutions. Water solubility was assessed using absorption spectroscopy by changing the concentration ∼1000-fold (190-690 µM to 0.19-0.69 µM) with a reciprocal change in pathlength (0.1-10 cm). All bacteriochlorins showed excellent solubility in water, except for a bacteriochlorin-imide that gave slight aggregation at higher concentrations. One bacteriochlorin was conjugated to a mouse polyclonal IgG antibody for use in flow cytometry with compensation beads for proof-of-principle. The antibody conjugate ofB2-NHSdisplayed a sharp signal upon ultraviolet laser excitation (355 nm) with NIR emission measured with a 730/45 nm bandpass filter. Overall, the study gives access to a set of water-soluble bacteriochlorins with desirable photophysical properties for use in multiple fields.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204.
authors.forename: Nuonuo
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204.
authors.forename: Jianbing
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204.
authors.forename: Mengran
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Chemistry, Washington University, St. Louis, MO 63130-4889.
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Mandal
authors.affiliation: NIRvana Sciences, Research Triangle Park, NC 27709-3169.
authors.forename: Rosemary B
authors.initials: RB
authors.lastname: Evans-Storms
authors.affiliation: NIRvana Sciences, Research Triangle Park, NC 27709-3169.
authors.forename: J Bruce
authors.initials: JB
authors.lastname: Pitner
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521-0403.
authors.forename: David F
authors.initials: DF
authors.lastname: Bocian
authors.affiliation: Department of Chemistry, Washington University, St. Louis, MO 63130-4889.
authors.forename: Dewey
authors.initials: D
authors.lastname: Holten
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lindsey