Bioorthogonal chemistries for nanomaterial conjugation and targeting

Abstract

Bioorthogonal chemistries are covalent reaction pairs that proceed in the presence of biological components with complete specificity. A suite of reactions has been described to date that provides scientists and engineers with diverse operational characteristics for different applications. Nanomaterials in particular have benefitted from these new capabilities, resulting in improved coupling efficiencies and multifunctionality. In this review, we will discuss the application of bioorthogonal chemistries to different nanomaterial systems, highlighting the advantages and limitations for use in bioconjugation. We will also describe how recent improvements in the reaction speed of catalyst-free bioorthogonal chemistries have enabled the successful coupling of nanomaterials directly to live cells. Using a recently developed reaction pair, tetrazine and trans -cyclooctene, the direct covalent coupling to cells has been shown to occur on time-scales that are relevant for biological studies and diagnostic applications and can even amplify nanomaterial binding greater than tenfold relative to traditional immunoconjugates. This powerful technique still maintains exquisite specificity, however, yielding robust results in clinical diagnostic applications using human tissue and blood samples. Future work will likely focus on further advancement of the in situ amplification technique, such as increasing nanomaterial binding, enabling multiplexed detection through the use of orthogonal reaction systems and extension to applications in vivo .

Pushing the limits of detection for proteins secreted from single cells using quantum dots

“…We note that TCO and PEG-TCO loading conditions were optimized in previous work to provide maximal reactive loading without affecting antibody binding affinity. 52 Antibody concentrations were determined by absorption measurement using a NanoDrop 2000 spectrophotometer. TMR modification level was determined to be ~2 dyes/antibody by absorption measurement.…”

“…[48][49][50] Recently, we improved the robustness and overall power of our chemical amplification (ChemAmp) technique by increasing the density of reactive TCO moieties on the antibody, which tend to bury within the antibody during bioconjugation procedures. 51 To date, the simple yet powerful ChemAmp technique has been employed to detect protein targets on live and fixed human cells, bacteria, and microvesicles using magnetic nanoparticles and QDs, 52 but it has not been applied to secreted proteins.…”

Covalent Immobilization of Antibodies through Tetrazine-TCO Reaction to Improve Sensitivity of ELISA Technique

“…Among these, the IEDDA reaction stands out from other bioorthogonal reactions due to its unmatchable kinetics (rate constant of up to 10 6 M −1 s −1 ) and its high specificity and biocompatibility [ 25 ]. Specifically, this reaction has been used to conjugate antibodies, which were later conjugated with tetrazine or TCO and then applied to cell imaging, nanoparticle functionalization, and targeted antibody therapy [ 27 , 28 ]. Attending to its characteristics and applications, we selected this reaction as the basis of system development to increase ELISA sensitivity.…”

The potential of bioorthogonal chemistry for correlative light and electron microscopy: a call to arms

“…However, GNPs in combination with bioorthogonal labelling have not been explored for this purpose. This is remarkable, since the inverse use of bioorthogonal chemistry-to synthesize protein/DNA-modified gold particles-has been reported [32,33]. In these studies, no change in GNP size was observed and hydrophobic, organometallic and hydrophilic moieties could be introduced onto the particles.…”