<?php
$pattern = "([あ-ん]+)[0-9]+";
$string = mb_ereg_replace($pattern, '「\\1」:\\0', $string);
?>
you can use \\n for capture group in replacement
<?php
$pattern = "([あ-ん]+)[0-9]+";
$string = mb_ereg_replace($pattern, '「\\1」:\\0', $string);
?>
you can use \\n for capture group in replacement