Tailoring Sensitivity in Electrochemical Nucleic Acid Hybridization Biosensing: Role of Surface Chemistry and Labeling Strategies

Abstract

Electrochemical nucleic acid hybridization biosensors have become a mainstay to detect DNA or RNA targets of interest in clinical diagnostics, environmental monitoring and food quality control. Despite the great progress they demonstrated during the last years, there is a constant demand to improve their performance, mainly in terms of sensitivity, simplicity of protocols and easy implementation in routine and decentralized determinations. Within this context, the tremendous possibilities offered by both, a judicious interfacing of the electrode surface, and the use of innovative labeling strategies not requiring nanomaterials or nucleic acid amplification, is discussed critically in this review.

Cutting-Edge Advances in Electrochemical Affinity Biosensing at Different Molecular Level of Emerging Food Allergens and Adulterants

“…The indirect methods have been applied to the determination of: (i) amplicons obtained by Express PCR [36]; (ii) extracted genomic (gDNA) [57] or mitochondrial (mtDNA) DNA [37] without previous amplification or fragmentation and after a simple denaturation step; iii) mitochondrial raw lysates without previous mtDNA extraction [37]. Most of these methods used disposable electrodes and, to achieve the sensitivity and selectivity demanded by this type of applications were, in some cases, coupled to the use of nanomaterials or nucleic acid amplification strategies, as well as to the use of MBs and to multi-enzymatic detector bioreceptors [37][38][39].…”

“…The biosensors recently developed for the determination of DNA fragments characteristic of allergens or adulterants try to replace the conventional PCR amplification by other shorter strategies (Express PCR [36]) or with simpler implementation in POC devices (not requiring a thermocycler) using multienzyme bioreceptors [37][38][39].…”

Antifouling (Bio)materials for Electrochemical (Bio)sensing

“…However, SHCP/MCH binary monolayers still display nonspecific background contributions, particularly from proteins [50], due to incomplete backfilling and irreproducibility issues during the assembling (attributed to the presence of surface defects and lateral diffusion of the SHCPs triggered after MCH backfilling) which have a negative impact on the hybridization efficiency and limit their long-term stability [42,44,48,49,51,52,53,54,55,56]. Nevertheless, a rational design of the surface chemistry involving the use of thioaromatic DNA monolayers (Figure 5a), ternary monolayers (Figure 5b) or tetrahedral DNA nanostructures (Figure 5c) has demonstrated allowing to control the spacing between the attached probes and minimizing nonspecific adsorptions endowing the modified interfaces with better storage stability and sensing performance in complex samples [57,58,59,60].…”

Advances in Electrochemical (Bio)Sensing Targeting Epigenetic Modifications of Nucleic Acids

“…The methodologies summarized in Table show the tendency to develop nucleic acid amplification‐free strategies, with the aim of facilitating their translation into routine clinical practice, and providing highly sensitive electrochemical biosensors of simple operation. The required sensitivity was achieved in combination with the use of nanomaterials, nanostructured electrode surfaces and/or multiple labels or multi‐enzyme labels loaded on appropriate detector bioreceptors . Importantly, these strategies are able to perform the determination of the target miRNA without previous reverse transcription of RNA to cDNA.…”