Is there a bus from Wan Chai City to Shenzen China? And what are the schedules of the bus trips?

I will arrive at SZ airport and planning to visit my friend to Wan Chai City, Hong Kong after the business trip in SZ China. There are 24 /7 bus from Shenzen airport to Wan Chai but i do not know if there are 24 hours bus trip from Wan Chai City, HK to SZ?