The present patent discloses the identification of small-molecule fluorescent probes constituted by pteroic acid moiety connected to near-infrared (NIR) dye via amino acids. These folate receptor (FR) targeted conjugates were shown to have high affinity for tumors that overexpress FRs. A selected compound from this new class, pteroyl-L-tyrosine-S0456 (OTL-0038), displays high affinity and specificity for FRs and was shown (i) to accumulate in vivo in tumor cells expressing FRs, and (ii) to be non-toxic in mice at clinical dose x 1000. This compound holds considerable promise for the location and detection of tumoral cells in the context of fluorescence guided surgery.