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. 2012 Feb 7;12(2):1657–1687. doi: 10.3390/s120201657

Table 1.

Types of conjugations between biomolecules and noble metal NPs.

Type of conjugation Pros Cons
Electrostatic interactions
(e.g., adsorption of negative charged DNA to positive charged gold NP)

  • - Very simple and straightforward to perform.

  • - Restricted to opposite charged biomolecules and NPs;

  • - Very sensitive to environmental properties (e.g., pH, ionic strength, etc.);

  • - Weak functionalization.
Chemisorption
(e.g., quasi-covalent binding of thiol-functionalized biomolecule to gold NP)

  • - Allows oriented functionalization;

  • - Very robust functionalization.

  • - Requires NPs with capping agents with weaker adsorption than the derivatization moiety;

  • - Usually requires modification of the biomolecule;

  • - Subject to interference by other chemical groups available for adsorption within the biomolecule;

  • - Affected by chemical degradation and surface oxidation of some NPs (e.g., silver).
Affinity-based
(e.g., His-tag protein binding to Ni-NTA derivatized gold NP)

  • - Allows oriented functionalization;

  • - Very straightforward binding between affinity pairs.

  • - Requires modification of both NPs and biomolecules with an affinity pair;

  • - Limited to availability of suitable binding affinity pairs.