Cell barcoding for single cell sequencing

A solid hydrogel around a cell mixture or nuclei mixture such that individual cells or individual cell nuclei are separated from each other by the hydrogel, wherein:

• the individual cells comprise heterologous oligonucleotides attached to cell membranes of the individual cells or the individual cell nuclei comprise heterologous oligonucleotides attached to nuclear membranes of the individual cell nuclei.