Catholic scholar and priest, Michael O’Carroll, CSSp, wrote the following on the Immaculate Conception:
The first apparently explicit testimony is in the Nisibene hymns of St Ephraem, a fourth century Syrian writer: “Certainly you are alone and your other are from every aspect completely beautiful, for there is no blemish in you, my Lord, ad no stain in your mother.” But there are other texts in the same author’s writings which, to put it mildly, call for subtle interpretation to maintain the doctrine—he spoke for example of Mary’s baptism.
The opinion of St Ambrose is also controverted; he did first establish the complete personal sinlessness of Mary. St Augustine held this latter doctrine; his opinion, on the Immaculate Conception is endlessly debated. His much quoted text “except the holy Virgin Mary, about whom, for the hour of the Lord, I want there to be no question” is offset by some enigmatic words which he used to counter the taunt of Julian of Eclanum, a Pelagian who said to him “you deliver Mary herself to the devil through the condition of her birth.” Unfortunately, in another way, Augustine’s negative influence on the development of the doctrine was for centuries decisive. He thought that original sin was transmitted by conjugal intercourse through inherent concupiscence. Christ was immune because he was conceived virginally—the conclusion was drawn that Mary was not. (Michael O’Carroll, CSSp, “The Immaculate Conception and Assumption of our Lady in Today’s Thinking” in Mary in the Church [ed. John Hyland; Dublin: Veritas, 1989], 44-56, here, p. 45)
Catholic Mariologist, Luigi Gambero, wrote the following on Ephrem the Syrian:
Ephrem’s insistence on Mary’s spiritual beauty and holiness, and her freedom from any stain of sin, has led some scholars to hold that he was aware of the privilege of the Immaculate Conception and to point to him as a witness to the dogma. Yet it does not appear that our author was familiar with the problem, at least not in the terms in which it was made clear by later tradition and the dogmatic declaration of 1854. In one passage he even used the term “baptized” to indicate her Son’s saving intervention in her regard:
Handmaid and daughter
of blood and water [am I] whom You redeemed and baptized. (Hymns on the Nativity 16, 10) (Luigi Gambero, Mary and the Fathers of the Church: The Blessed Virgin Mary in Patristic Thought [San Francisco: Ignatius Press, 1999], 110)
For more on the lack of evidence for the Immaculate Conception among the patristic-era writers, see my article:
On Luke 1:28, which is the most popular "proof-text" Catholic apologists appeal to from the Bible to support this dogma, see:
When one examines both the Bible and early Chrisitan writings, there is no meaningful evidence supporting Rome's claim that the Immaculate Conception is an apostolic tradition.