Potential applications for Biosensors (Ekrami, Elena, et al. 2021) and (Vigneshvar, S., et al. 2016)

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Ekrami, Elena, et al. “A Review on Designing Biosensors for the Detection of Trace Metals.” Applied Geochemistry, vol. 127, Apr. 2021, p. 104902. DOI.org (Crossref), doi:10.1016/j.apgeochem.2021.104902.

Introduction/Why the problem is important

• One of fundamental issues in mining activities is the pollution caused by the presence of trace metals that can spread through the soil and infiltrate water, thereby directly affecting the environmental index of sustainability.
• Many efforts have been made to introduce portable sensors for controlling trace metal concentrations in the environment.
• Mining plays a crucial role in the economy of countries in which a big share of gross domestic production (GDP) is linked to mineral resources like Chille, Ghana, Peru.
• The demand for minerals is greatly growing. Moreover, in recent years, due to the increase in mining activities, more attention should be devoted to the issues related to sustainability of mining activities, including pollution control, acid mine drainage and safety.
• According to this study, sustainable mining will be considered as the key factor in future of mining projects that will have the least damaging effects on the environment and the greatest profits for future generations
• Conventional methods while precise, require fancy technology and are expensive.

Biosensors that seem to be more closely related to physics than to synthetic biology:

• Electrochemical biosensors:
  • Recognizes differences in the electrochemical parameters like current, voltage, potential, and electroluminescence, based on the presence or absence of metal ions.
  • If the electrochemical detector and the electrolyte are selected properly, they will provide a more cost-effective means for gaining signals with better stability and sensitivity over time and with possible fewer interferences, when compared to other kinds of biosensors.
• Field-effect transistor sensors:
  • Field-effect transistors (FETs) have been used for portable, label-free sensing applications in environmental and healthcare monitoring.
  • Compatible with digital read out techniques
  • Based on the absorption or interaction of a charged species
  • To allow for selective detection of a special species, the FET’s surface is chemically functionalized with specific binding groups.
  • Identification is achieved by measuring current.
  • Precision and accuracy of FET sensors depends on concentration of ions and essential features of the material
• Chemical based sensors:
  • Chemical-based metal sensors apply chelating ligands as a sensing platform to discover metal-chelator binding by evaluating spectroscopic changes, like fluorescence.
• Optical biosensors:
  • Detects desired analyte by assembly of a light source, optical transducer system, sensing element, and a detector.
  • Types and techniques include:
    • Fluorescence biosensors
    • Calorimetric biosensors
    • Surface enhanced Raman scattering
    • Localized surface plasmon resonance
    • Surface plasmon resonance

More biology related biosensors

• Enzyme based biosensors

  • Trace metals such as metalloproteins, are required for enzyme activity. Thus, detection is based by inhibition or activation of enzyme activity.

• Bacterial cell-based biosensors aka Whole Cell Biosensors

  • Microorganisms have genetic components responsible for detecting external stress factors. The metal sensing device in such biosensors are metalloproteins which also work as transcriptional factors that adjust the downstream expression of genes in the presence of metal(loid) ions
  • Bacterial cell based biosensors can be constructed by recombining genes containing promoter region of the metal responsive operon and reporter genes
  • Main advantages: cheapness, simplicity, capability to measure bioavailability.
  • The sensitivity and selectivity of WCB to metal(loid) ions are modulated by biochemically and genetically engineering host E.coli and other bacterial cells
  • The most advantageous aspect of WCBs, would be calculating the pollutants in the environment, which is also this system’s weakest point.
  • One of the disadvantage of bacterial cell-based biosensors is the size of the target pollutants. Pollutants like algal toxins, nondegradable phenolic compounds, and perchlorinated chemicals, which cannot enter the cells due to their size, will not be detected

• Metal-binding protein-based sensors coupled with DNA probes

  • Metal(loid) sensors are mainly applied biological systems that are commonly dependent on proteins which are able to interact with metal (loid) ions, mostly the MerR family proteins
  • MerR family of proteins have been used as metal sensing devices, with the expression of reporter genes representing the quantifiable signal.
  • Most metal biosensors use metal-interacting domains in transcriptional regulators, and the interaction between them is demonstrated by the expression of reporter proteins with fluorescence or enzymatic activity.

• Split protein system based sensors

  • Split protein systems were produced to associate when they are close enough to each other; so, if a two-part protein like enzymes or fluorescent proteins was rejoined by target molecules acting as molecular glue, the reactivity of proteins could show the presence of the target molecules, thereby functioning as biosensors.

• Aptamers

  • Advantages: stability in harsh environmental conditions that include extreme pH or high temperature, ease of synthesis and modification, small size, long-time storage without functional degradation, low price, and good chemical stability
  • They have the perfect potential to attach to a particular target thus making them a reliable detection element
  • Method for production is relatively easy

Article no.2: Vigneshvar, S., et al. “Recent Advances in Biosensor Technology for Potential Applications – An Overview.” Frontiers in Bioengineering and Biotechnology, vol. 4, Feb. 2016. DOI.org (Crossref), doi:10.3389/fbioe.2016.00011.

Table summarizing some of the biosensors, their applications and providing bibliography

Table summarizing types of biosensors, their characteristics and applications