<?php
$string = 'PHP is a server side web programming language , PHP is amazing , I love PHP';
$array = array('html','css','javascript','ajax','html5','css3','jquery','PHP');
$escaped_array = array_map(function($value){
return preg_quote($value, '/');
}, $array);
$regex = '/\b(' . implode('|', $escaped_array) . ')\b$/';
preg_match($regex, $string, $match);
print_r($match);