Polydopamine: surface coating, molecular imprinting, and electrochemistry—successful applications and future perspectives in (bio)analysis

Norepinephrine as new functional monomer for molecular imprinting: An applicative study for the optical sensing of cardiac biomarkers

The continuous research for alternatives to antibody-based detection drove, in the last decades, the development of numerous strategies. Molecularly imprinted polymers (MIPs) emerged thanks to the low-cost and long-term stability features, where the choice of natural functional monomer(s) represents the key step for efficient imprinting of biomolecules. The chemical structure of dopamine (DA), one of the most used natural functional monomers, provided the inspiration for this work. We wondered why norepinephrine (NE) that differs from dopamine only for an additional hydroxyl group was not investigated at all in biosensing applications. In fact, there is only one paper exploiting polynorepinephrine (PNE) in molecular recognition applications, taking advantage of molecular imprinting, but not for biosensing purposes. In contrast, hundreds of papers describe polydopamine-based sensors. Therefore, we firstly investigated how the additional hydroxyl group of NE could affect the properties of the resulting polymer, and how these properties could be exploited for biosensing applications. The results highlighted the reduced non-specific adsorption of proteins onto PNE with respect to dopamine polymer. Furthermore, as a case study, we successfully developed a PNE-based imprinted biosensor for the early detection of Troponin I, a crucial biomarker for heart failure, by coupling the MIP biosensor with surface plasmon resonance (SPR) detection. The results indicate the feasible use of imprinted PNE as synthetic receptor for biomolecules, opening new perspectives for this biopolymer, so far not considered, and encouraging further investigations on its potential application in biosensing.

Polydopamine-assisted surface modification for orthopaedic implants

Along with the massive use of implants in orthopaedic surgeries in recent few decades, there has been a tremendous demand for the surface modification of the implants to avoid surgery failure and improve their function. Polydopamine (PDA), being able to adhere to almost all kinds of substrates and possessing copious functional groups for covalently immobilizing biomolecules and anchoring metal ions, has been widely used for surface modification of materials since its discovery in the last decade. PDA and its derivatives can be used for the surface modification of orthopaedic implants to modulate cellular responses, including cell spreading, migration, proliferation, and differentiation, and may thereby enhance the function of existing implants. In addition, the osseointegration and antimicrobial properties of orthopaedic implants may also be improved by PDA-based coatings. The aim of this review is to provide a brief overview of current advances of surface modification technologies for orthopaedic implants using PDA and its derivatives as a medium. Given the versatility of PDA-based adhesion, such PDA-assisted surface modification technologies will certainly benefit the development of new orthopaedic implants.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Surface treatments of orthopaedic implants, which are normally inert materials, are essential for their performance in vivo. This review summarizes recent advances in the surface modification of orthopaedic implants using facile and highly versatile techniques based on the use of polydopamine (PDA) and its derivatives.