Table 3.

Review of the main advantages, challenges and trends of the main target analytes for electrochemical printed biosensors (referenced articles are limited to the recent literature focusing on critical evaluation of positive, challenging aspects and trends of each class of analyte).

	Advantages	Challenges	Main Trends	Ref
Whole Cells (Eukaryotic and Pathogens)	direct detection without need for sample pre-treatment to extract and purify sample, long life-time, higher stability during time	low selectivity, challenging the detection with high sensitivity, risk of contamination, often slow reactions	organic printed biosensors, degradable sensing elements, sensors integrated in glassware and scaffolds, use of disposable non-conventional substrates, use of nanostructures to enhance sensitivity	[5,93,156,157,158]
Nucleic Acids	wide range of application, high specificity	needed labels, time consuming because of purification step required, high costs	nanostructures, nano-hybrid materials, combine amplification techniques with the electrochemical detection	[159,160,161,162,163]
Proteins	simplicity, broad spectrum of applications, well-known structure, small dimensions, sensitivity, broad range of available recognition elements with high selectivity and strong binding interaction, ease validation	poor chemical, thermal and pH stability, risk of degradation due to substrate–protein interaction, high costs of antibodies for ensure selectivity, immunogenicity	low-cost disposable materials, simplify protocols, use of direct biomolecules printing, imprinted polymers, composite materials	[164,165,166]
Metabolites and Electrolytes	indirectly correlated with a plethora of physio-pathological processes, detectable in multiple body fluids, ideal for non-invasive continuous monitoring of health	long-term stability of enzymes, interferences of charged non-target analytes	novel selective materials, improve integration of sensors and microfluidic circuit	[167,168,169]