PHP convert unicode to hex
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An app wants me to insert strings as ` text encoded using hex values in proper coding.`, the encoding being `Unicode_No_Compression`

For example, for `Sześć siedem` the correct HEX string is `0053007A0065015B0107002000730069006500640065006D`,  
`Źdźbło` = `01790064017A00620142006F`  
`String with no special chars` 
=`0053007400720069006E0067002000770069007400680020006E006F0020007300700065006300690061006C002000630068006100720073`

I tried playing with MySQL `HEX()`/`UNHEX()` and `dechex()` PHP, but been unable to figure out how to make this conversion. Any ideas?