Disclosed herein include systems, methods, compositions, and kits for 5′-based gene expression profiling. Some embodiments provide synthetic particles (e.g., beads) associated with a first plurality of oligonucleotide barcodes and a second plurality of oligonucleotide barcodes. In some embodiments, nucleic acid targets (e.g., mRNAs) are initially barcoded on the 3′ end with the first plurality of oligonucleotide barcodes and subsequently barcoded on the 5′ end following a template switching reaction and intermolecular hybridization with the first plurality of oligonucleotide barcodes and extension. Immune repertoire profiling methods are also provided in some embodiments.