An in vitro method for preparing a recombinant full-length antibody library, comprising: providing primary immune cells previously obtained from at least one mammalian donor; isolating in a plurality of monodisperse droplets single immune cells from said primary immune cells; generating a plurality of recombinant fusion polynucleotides each comprising a first polynucleotide encoding a heavy chain variable domain and a second polynucleotide encoding a light chain variable domain, wherein said heavy chain variable domain and light chain variable domain on each of said plurality of recombinant fusion polynucleotides are a cognate pair from one of said isolated primary immune cells, wherein each of said plurality of recombinant fusion polynucleotides further comprise a linker polynucleotide linking said first and second polynucleotides; circularizing via Gibson Assembly each of said plurality of linear recombinant fusion polynucleotides; and inserting a third polynucleotide comprising a sequence encoding a promoter and a sequence encoding a constant region between said first and second polynucleotide in each of said circularized recombinant fusion polynucleotides, thereby generating at least 1,000 unique recombinant full-length antibody expression constructs, thereby generating a recombinant full-length antibody library, wherein the step of isolating single immune cells from said primary immune cells comprises encapsulating said single immune cells into a plurality of monodisperse droplets with beads comprising bound polynucleic acid probes with sequences that are complementary to both, polynucleotides encoding heavy chain variable domains and polynucleotides encoding light chain variable domains in a reaction mixture which lyses the primary immune cells and encourages polynucleic acid hybridization, thus allowing the beads to capture polynucleotides encoding heavy chain variable domains and polynucleotides encoding light chain variable domains. providing primary immune cells previously obtained from at least one mammalian donor; isolating in a plurality of monodisperse droplets single immune cells from said primary immune cells; generating a plurality of recombinant fusion polynucleotides each comprising a first polynucleotide encoding a heavy chain variable domain and a second polynucleotide encoding a light chain variable domain, wherein said heavy chain variable domain and light chain variable domain on each of said plurality of recombinant fusion polynucleotides are a cognate pair from one of said isolated primary immune cells, wherein each of said plurality of recombinant fusion polynucleotides further comprise a linker polynucleotide linking said first and second polynucleotides; circularizing via Gibson Assembly each of said plurality of linear recombinant fusion polynucleotides; and inserting a third polynucleotide comprising a sequence encoding a promoter and a sequence encoding a constant region between said first and second polynucleotide in each of said circularized recombinant fusion polynucleotides, thereby generating at least 1,000 unique recombinant full-length antibody expression constructs, thereby generating a recombinant full-length antibody library, wherein the step of isolating single immune cells from said primary immune cells comprises encapsulating said single immune cells into a plurality of monodisperse droplets with beads comprising bound polynucleic acid probes with sequences that are complementary to both, polynucleotides encoding heavy chain variable domains and polynucleotides encoding light chain variable domains in a reaction mixture which lyses the primary immune cells and encourages polynucleic acid hybridization, thus allowing the beads to capture polynucleotides encoding heavy chain variable domains and polynucleotides encoding light chain variable domains. <EOS>