function quote_escape(&$str) {
$str = '"' . mysql_real_escape_string(chop($str)) . '"';
}
$brands = explode(',', $brand_value);
array_walk($brands, "quote_escape");
$brands = implode(',', $brands);
или
function quote_escape($str) {
return '"' . mysql_real_escape_string(chop($str)) . '"';
}
$brands = implode(',', array_map("quote_escape", explode(',', $brand_value)));