Bs were collected and their phagocytic ability was assessed. Sheep lymphocyte separation medium (TBD, Tianjin, China) was used to isolate the cells. Monocytes cultured in RPMI-1640 (Gibco, Grand Island, NY, USA) medium supplemented with 10 FBS. Medium was changed every 24 hours. To assess phagocytosis, cells were cultured for 72 hours. Briefly, cells were incubated in 100 mL culture medium containing 0.5Author ContributionsConceived and designed the experiments: SD ZL. Performed the experiments: SD YZ YY GL KY QW WL ZD. Analyzed the data: SD. Contributed reagents/materials/analysis tools: GL WL ZL. Wrote the paper: SD QW.
Exertion of cell functions is critically dependent on genome fidelity, which is threatened by various DNA lesions [1?]. Abasic site (AP site) is one of commonly observed DNA mutagenic and carcinogenic lesions [4], arising from spontaneous depurination or depyrimidination during in vivo base excision repair (BER) of damaged DNA bases [5]. Therefore, recognition of the AP site holds great promise for diagnostic and therapeutic applications [6]. Although the AP site can be targeted by non-fluorescent small molecules including binder/insertor heterodimer [5,7?], metalloinsertor [6,10], redox probe [11], nitroxide spin label [12], and DNA base analog [13], fluorescent small molecules have received much attention due to simplicity and cost saving in the detection technologies. In this aspect, some fluorophores were found to be effective such 
as environment polarity-sensitive naphthalene derivative [14] as well as the organic probes possessing hydrogen bond moieties that are complementary to the bases opposite the AP site, including naphthyridine [15,16], pyrazine [17], lumazine [18], pteridine [19,20] and flavin [21] derivatives. However, dueto formation of the Epigenetic Reader Domain static DNA complexes, excited state electron transfer, and the other intricate processes, fluorescence quenching was usually observed [15?1]. More seriously, the presence of the AP site-containing DNA (AP-DNA) did not alter the fluorophores’ emission wavelength. Thus, high background emissions can not be overcome using these probes as the AP site binders. We have being focused on seeking new fluorophores exhibiting novel optical properties upon binding to the AP site. A new longwavelength emission band arising from an excited-state intramolecular proton transfer (ESIPT) probe [22], fisetin, one of natural 3-hydroxyflavonols, was observed in the presence of the AP site. Recently, we found that berberine [23], one of natural isoquinoline alkaloids, can selectively bind to the AP site with a sequencedependent manner. Although fluorescence enhancement was observed for these fluorophores, the alteration in their emission wavelengths upon binding to the AP site was not more than 60 nm. Herein, another alkaloid, sanguinarine (SG), was employed to achieve a much larger emission shift up to 170 nm when binding to the AP site. SG belongs to a benzophenanthridine alkaloid, which is known for its antitumor inhibitor property and possesses the potential for selective/DNA Abasic Site Binderpreferential elimination of cancer cells [24?8]. Besides its interaction with proteins [29] and amino acids [30], one of the potential antitumor activities of SG is believed to result from its highly specific binding to many types of nucleic acid structures and subsequent modification of the genetic information [31]. SG exhibits a pH-dependent structure equilibrium in aqueous solution between the positivel.Bs were collected and their phagocytic ability was assessed. Sheep lymphocyte separation medium (TBD, Tianjin, China) was used to isolate the cells. Monocytes 
cultured in RPMI-1640 (Gibco, Grand Island, NY, USA) medium supplemented with 10 FBS. Medium was changed every 24 hours. To assess phagocytosis, cells were cultured for 72 hours. Briefly, cells were incubated in 100 mL culture medium containing 0.5Author ContributionsConceived and designed the experiments: SD ZL. Performed the experiments: SD YZ YY GL KY QW WL ZD. Analyzed the data: SD. Contributed reagents/materials/analysis tools: GL WL ZL. Wrote the paper: SD QW.
Exertion of cell functions is critically dependent on genome fidelity, which is threatened by various DNA lesions [1?]. Abasic site (AP site) is one of commonly observed DNA mutagenic and carcinogenic lesions [4], arising from spontaneous depurination or depyrimidination during in vivo base excision repair (BER) of damaged DNA bases [5]. Therefore, recognition of the AP site holds great promise for diagnostic and therapeutic applications [6]. Although the AP site can be targeted by non-fluorescent small molecules including binder/insertor heterodimer [5,7?], metalloinsertor [6,10], redox probe [11], nitroxide spin label [12], and DNA base analog [13], fluorescent small molecules have received much attention due to simplicity and cost saving in the detection technologies. In this aspect, some fluorophores were found to be effective such as environment polarity-sensitive naphthalene derivative [14] as well as the organic probes possessing hydrogen bond moieties that are complementary to the bases opposite the AP site, including naphthyridine [15,16], pyrazine [17], lumazine [18], pteridine [19,20] and flavin [21] derivatives. However, dueto formation of the static DNA complexes, excited state electron transfer, and the other intricate processes, fluorescence quenching was usually observed [15?1]. More seriously, the presence of the AP site-containing DNA (AP-DNA) did not alter the fluorophores’ emission wavelength. Thus, high background emissions can not be overcome using these probes as the AP site binders. We have being focused on seeking new fluorophores exhibiting novel optical properties upon binding to the AP site. A new longwavelength emission band arising from an excited-state intramolecular proton transfer (ESIPT) probe [22], fisetin, one of natural 3-hydroxyflavonols, was observed in the presence of the AP site. Recently, we found that berberine [23], one of natural isoquinoline alkaloids, can selectively bind to the AP site with a sequencedependent manner. Although fluorescence enhancement was observed for these fluorophores, the alteration in their emission wavelengths upon binding to the AP site was not more than 60 nm. Herein, another alkaloid, sanguinarine (SG), was employed to achieve a much larger emission shift up to 170 nm when binding to the AP site. SG belongs to a benzophenanthridine alkaloid, which is known for its antitumor property and possesses the potential for selective/DNA Abasic Site Binderpreferential elimination of cancer cells [24?8]. Besides its interaction with proteins [29] and amino acids [30], one of the potential antitumor activities of SG is believed to result from its highly specific binding to many types of nucleic acid structures and subsequent modification of the genetic information [31]. SG exhibits a pH-dependent structure equilibrium in aqueous solution between the positivel.
