This would be the basis but you might need to adapt it yourself.
Sub chex()
Dim osld As Slide
Dim newsld As Slide
Dim oshp As Shape
Dim otr As TextRange
Dim b_found As Boolean
Dim s As Long
Const Findstring As String = "This is me" ' change to suit
For Each osld In ActivePresentation.Slides
For Each oshp In osld.Shapes
If oshp.HasTextFrame Then
If oshp.TextFrame.HasText Then
Set otr = oshp.TextFrame.TextRange
For s = 1 To otr.Sentences.Count
If InStr(LCase(otr.Sentences(s)), LCase(Findstring)) > 0 Then
b_found = True
End If
If b_found Then Exit For
Next s
End If
End If
If b_found Then Exit For
Next oshp
If b_found Then Exit For
Next osld
If b_found Then
Set newsld = ActivePresentation.Slides.Add(1, ppLayoutText)
newsld.Shapes(1).TextFrame.TextRange = "Sentence Found"
newsld.Shapes(2).TextFrame.TextRange = otr.Sentences(s)
End If
End Sub