Cancer biomarkers span small and large molecules and strategies for prevention and treatment hinge on valid biomarker development, diagnostic performance and suitable assay approaches. Here, we demonstrate the role of electrochemical enzyme assays, with reliance on bio recognition, together with chemoreceptors for small molecule determination of target molecules relevant to diagnosis and treatment, therapy tracking and surveillance. The use of redox and conducting polymers serve to enhance binding and selectivity for cofactor electrocatalysis (nicotinamide adenine dinucleotide) realising assays for glyceraldehyde-3-phosphate dehydrogenase (up to 60 U mL^-1), lactate dehydrogenase (up to 10 U mL^-1), while indirect determination of enzyme produced naphthol realised acid phosphatase determination over the range 1-20 nM. We also present biorecognition of sialic acids (N-acetylneuraminic acid (Neu5Ac) N-glycolyl-D-neuraminic acid (Neu5Gc)) which function as the terminal sugar moiety in most glycoproteins, mediating critical roles related to cell recognition while varying in the progression of cancers. 4-mercaptophenyl boronic acid self-assembled monolayers and 3-thienyl boronic acid co-polymers were tested for their ability to discriminate sialic acid binding in the presence of other monosaccharides. The latter studies relied on DC and AC voltammetry and electrochemical impedance spectroscopy studies, probing surface interactions and providing confirmation of sialic acid detection at the modified electrodes.