rewrite MSXML2.DOMDocument to Xml.xmlDocument

I have the following VB function which I need to rewrite for VB.Net (VS2013) I have been breaking my head over this, anyone know how to do this:

Public Function EncodeBase64(ByRef arrData() As Byte) As String

    Dim objXML As MSXML2.DOMDocument
    Dim objNode As MSXML2.IXMLDOMElement

    Set objXML = New MSXML2.DOMDocument

    ' byte array to base64
    Set objNode = objXML.createElement("b64")
    objNode.DataType = "bin.base64"
    objNode.nodeTypedValue = arrData
    EncodeBase64 = objNode.Text

    Set objNode = Nothing
    Set objXML = Nothing

End Function