Compositions of matter for detection assays

A composition of matter comprising a ribonucleoprotein complex and a blocked nucleic acid molecule, wherein the blocked nucleic acid molecule is represented by Formula III, wherein

• Formula III in the 5′-to-3′ direction comprises:
• T-D-M-A-(B-L)J-C;
• wherein T is 17-135 nucleotides in length;
• D is 0-10 nucleotides in length;
• M is 1-25 nucleotides in length or is absent, wherein if M is absent then T-D and A-(B-L)J-C are separate nucleic acid strands;
• A is 0-15 nucleotides in length and comprises at least 50% sequence complementarity to D;
• B is 4-12 nucleotides in length and comprises at least 50% sequence complementarity to T;
• L is 3-25 nucleotides in length;
• J is an integer between 1 and 10;
• C is 4-15 nucleotides in length;
• wherein the blocked nucleic acid molecules comprise a sequence complementary to a gRNA;
• wherein the ribonucleoprotein complex comprises a nucleic acid-guided nuclease and the gRNA;
• wherein the nucleic acid-guided nuclease exhibits cis-cleavage activity and trans-cleavage activity;
• and wherein a Kd of the blocked nucleic acid molecules to the RNP is about 105-fold greater or more than the Kd of an unblocked nucleic acid molecules resulting from unblocking of the blocked nucleic acid molecules.