Chapter Four · failure evidence
What In Vitro Binding Assays got wrong, from 57 dissertations
In vitro binding assays frequently encounter technical obstacles such as non-specific background binding, surface fouling, and insufficient biophysical signal detection. Furthermore, measured in vitro affinities often fail to reflect cellular and in vivo activity, while mathematical binding models struggle to capture complex multivalent interactions. These records come from PhD theses at 19 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Non-specific binding and surface fouling generate excessive background noise or false positive interactions
Assays including ELISAs, bead capture, immunoprecipitation, and fluorescence polarization frequently fail because target proteins or reporters stick non-specifically to surfaces, membranes, or assay plates. This non-specific adsorption obscures true binding signals, elevates background in negative controls, and yields false-positive binding curves.
Tried and failed
baculovirus particle ELISA using recommended coating dilution applied to antibody specificity screening. Reason: Recommended dilution caused false positive non-specific binding from direct antibody binding to the microplate
Tried and failed
TR-FRET assay for protein-protein interactions applied to membrane-associated enzyme binding affinity. Reason: Full-length protein exhibited non-specific stickiness, yielding false-positive saturable binding curves with negative controls.
In vitro and in vivo studies of two essential MRSA cell wall synthesis enzymes · Harvard
Considered and rejected
Considered and rejected: Transwell bidirectional transport assay was rejected for assessing THC transport due to excessive intracellular retention and non-specific binding, prompting cellular accumulation assays
(-)-Δ9-tetrahydrocannabinol and pregnancy: transporter-mediated tissue distribution and drug interactions · ResearchWorks
Tried and failed
photoaffinity labeling with mass spectrometry target identification applied to small molecule protein target discovery. Outcome: no signal. Reason: candidate protein enrichment was a non-specific false positive, failing thermal shift validation
Considered and rejected
Considered and rejected: Rejected non-fixed live-cell staining in MRI phantoms because absence of serum blocking caused extensive non-specific binding of SPIONs.
Magnetic resonance strategies for tracking immune cells · University of Nottingham Repository
Considered and rejected
Considered and rejected: Ceased testing synthetic peptide binders (RRGW, WGRR, Fc-III-4C) because binding signal was below or equivalent to non-specific background binding to ELISA plates.
Collagen Anchoring Agonist Antibodies for Cancer Immunotherapy · MIT
Considered and rejected
Considered and rejected: Rejected poly-L-lysine (PLL) slide coating due to prominent non-specific probe binding background
Single-cell imaging assay for rapid antimicrobial resistance testing · Oxford
Considered and rejected
Considered and rejected: SNAP-tag system for cuticle pore permeability assay due to non-specific background binding to the pharynx.
Patterning of the apical extracellular matrix at sense organs · Harvard
Considered and rejected
Considered and rejected: Rejected Ni-NTA resin in favor of TALON (Co2+) affinity chromatography due to poor purity and non-specific binding
Investigating tRNA Release from the Bacterial Ribosome · Penn
Tried and failed
intact protein enrichment before digestion applied to modified peptide identification in proteomics. Outcome: worse than baseline. Reason: non-specific binding and interference from unlabeled background peptides reduced target identification depth
Developing novel mass spectrometry-based approaches to globally investigate protein glycosylation · Georgia Tech
Tried and failed
direct antigen-carrier protein immobilization on polyethersulfone membranes applied to amperometric competitive immunosensor assays. Outcome: no signal. Reason: insufficient amino groups on gelatin caused low specific binding and high non-specific background
Biological and artificial receptors in affinity sensor for water toxins detection · Cranfield
Tried and failed
co-immunoprecipitation of endogenous proteins applied to transcription factor protein-protein interactions. Outcome: no signal. Reason: antibody non-specific binding caused high background signal present in both control and knockout lysates
B-MYB and FOXM1 drive cell division through cooperative regulation of cell cycle genes. · Harvard
Tried and failed
metabolic inhibition to reduce background substrate binding applied to radiolabeled lipid uptake assays. Outcome: no signal. Reason: metabolic poisons halt active processing but do not eliminate passive, non-specific hydrophobic membrane adsorption
CHARACTERIZING THE ROLES FOR HOST-DERIVED LIPIDS DURING MYCOBACTERIUM TUBERCULOSIS INFECTION · Cornell
Tried and failed
whole-cell ELISA for monoclonal antibody screening applied to bacterial antigen-specific human monoclonal antibodies. Outcome: no signal. Reason: produced high non-specific background binding to negative controls and assay surfaces
Identification of pneumococcal vaccine antigens using Reverse Vaccinology 2.0 · Imperial
Tried and failed
high temperature thermal lysis of membrane vesicles applied to hydrogel microparticle biomolecule assays. Reason: high heat caused lipid and lipoprotein fouling leading to severe non-specific probe background binding
Tried and failed
single molecule magnetic bead capture assay applied to low concentration DNA detection. Outcome: no signal. Reason: severe non-specific binding of protein reporter to carboxylated magnetic beads caused high background
Applications of Engineered Proteins in Redox Biology and Biomarker Detection Assay Development · MIT
Considered and rejected
Considered and rejected: Rejected column-based online immunoprecipitation due to high background signals from unspecific binding and carryover
Biomarker qualification for drug-induced liver injury across species using immunoaffinity mass spectrometry · Publikationssystem UB Tuebingen
Considered and rejected
Considered and rejected: Rejected inside-out membrane vesicular transport assays due to high non-specific binding of lipophilic drugs and rapid leakage of high-permeability compounds.
Predicting Human Fetal Drug Exposure to Placental P-glycoprotein Substrates by PBPK Modeling and Simulation · ResearchWorks
Tried and failed
fluorescence polarization competition assay for screening binding applied to macrocyclic protein-protein interaction inhibitors. Outcome: no signal. Reason: peptide precipitation and non-specific plate sticking caused elevated anisotropy and decreased total fluorescence artifacts
Generating macrocyclic inhibitors of protein-protein interactions · EPFL
In vitro binding affinities and motifs fail to predict in vivo cellular occupancy and functional activity
In vitro binding measurements and enriched sequence motifs regularly fail to reproduce when tested in living cells or crosslinking assays. Disparities arise because isolated in vitro assays lack native cellular transport mechanisms, dynamic contexts, cooperative binding partners, and post-translational modifications.
Tried and failed
fixed tissue immunohistochemistry binding assay applied to predicting in vivo antibody transcytosis. Outcome: no signal. Reason: fixed-tissue binding affinity failed to capture dynamic cellular transport and transcytosis mechanisms in vivo
Tried and failed
in vitro binding affinity profiling applied to predicting in vivo genomic occupancy. Outcome: did not generalise. Reason: in vitro specificity differences did not predict cellular binding site occupancy
Regulatory consequences of variation in transcription factor-DNA binding · Harvard
Tried and failed
fixed cell microarray screening for protein interactions applied to validating viral glycoprotein host receptors. Outcome: no signal. Reason: Microarray binding hits failed to reproduce when assayed on live cells via flow cytometry.
Structural basis of antibody-mediated immunity against Crimean-Congo hemorrhagic fever virus glycoproteins · UT Austin
Tried and failed
peptide screening using surface plasmon resonance affinity applied to T cell receptor functional activation prediction. Outcome: no signal. Reason: Micromolar binding affinity failed to translate into functional downstream cellular activation
Tried and failed
in vitro high-throughput motif enrichment screening applied to identifying in vivo protein-RNA binding motifs. Outcome: did not generalise. Reason: weakly enriched in vitro motifs failed to show corresponding binding peaks in in vivo crosslinking validation
Tried and failed
predicting in vivo occupancy from in vitro affinity applied to transcription factor binding domain mutants. Outcome: did not generalise. Reason: in vivo binding showed a sharp threshold loss rather than reflecting the continuous in vitro affinity gradient
Regulatory consequences of variation in transcription factor-DNA binding · Harvard
Tried and failed
in vitro high-throughput secondary motif identification applied to in vivo RNA-protein binding enrichment. Outcome: did not generalise. Reason: secondary low-affinity binding motifs detected in vitro lacked robust enrichment in in vivo crosslinking-immunoprecipitation peaks
Lost to a baseline
Branched peptides K(Ac)-Y-E-L-K(Ac)-a-a, K(Ac)-Y-E-L-K(H-Y-M)-a-a, and K(Ac)-Y-E-L-K(Y-E-T)-a-a failed to outperform lead dual-functionalized peptides in in vitro vancomycin antagonism at a 5:1 molar ratio despite reported up to 28-fold higher binding affinity.
Considered and rejected
Considered and rejected: Rejected exploratory in vitro binding assays for factor specificity, favoring in vivo cross-linking/perturbation due to lack of cooperative RBPs and post-translational modifications in vitro.
Quantitative modeling of 5' splice site subclass regulation and evolution · MIT
Considered and rejected
Considered and rejected: Rejected Thioflavin T (ThT) labeling in vitro for generating ground truth due to lack of cellular context, potential non-specific binding, and incompatibility with live dynamic intracellular interactions
Intelligent and Self-Driving Microscopy of Protein Aggregation in Neurodegenerative Diseases · EPFL
Biophysical and optical biosensing platforms fail to detect measurable binding signals
Biosensing techniques such as surface plasmon resonance, localized surface plasmon resonance, circular dichroism, and fluorescence struggle with poor signal-to-noise ratios and low sensitivity. These instruments often yield false negatives or fail to register target interactions due to low binding densities, minimal optical contrast, or assay pipeline instability.
Tried and failed
surface plasmon resonance validation screening applied to RNA-binding protein small molecule interactions. Outcome: unstable. Reason: could not establish robust and reproducible binding assay pipelines for the protein panel
High Throughput Screening for Small Molecule Interactions with Nucleic Acid Binding Proteins · MIT
Tried and failed
biophysical assays to detect direct target binding applied to enzyme inhibitor validation. Outcome: no signal. Reason: SPR and DSF failed to detect binding interaction despite functional inhibition
Targeting the streptococcal virulence factor SpyCEP as a novel therapeutic approach · Imperial
Tried and failed
responsive polymer shell coating for plasmonic biosensing applied to protein detection via LSPR shifts. Outcome: no signal. Reason: Target protein binding caused no concentration-dependent localized surface plasmon resonance wavelength shifts across various polymerizations
Tried and failed
circular dichroism to detect surface antibody coatings applied to protein nanoparticle surfaces. Outcome: no signal. Reason: antibody concentration on nanoparticle surfaces was below instrument detection limit despite functional surface binding
Engineering Biomaterial - Protein Corona Interactions to Mediate Biological Responses · Georgia Tech
Tried and failed
split-ubiquitin yeast two-hybrid assay applied to extracellular receptor-ligand interactions. Outcome: no signal. Reason: assay failed to detect extracellular peptide-receptor binding, producing false negatives despite high-confidence structural predictions
Tried and failed
direct protein physisorption onto sensor surface applied to optical biosensing transducers. Outcome: no signal. Reason: insufficient surface binding density or low refractive index contrast prevents measurable optical resonance shifts
All-Dielectric Nanophotonic via Glass Fluid Instabilities · EPFL
Tried and failed
zeta potential measurement of nanoparticle surface binding applied to molecularly imprinted polymer target binding detection. Outcome: no signal. Reason: No discernible change in zeta potential observed upon target incubation, possibly due to steric hindrance.
Lost to a baseline
TSM biosensor could not directly calculate affinity binding constants (K), which UV spectroscopy provided for strong intercalators.
Development of a TSM Biosensor for the Determination of DNA- Drug Interactions: A Novel Method to Assist Drug Development · De Montfort Open Research Archive (DORA)
Tried and failed
intrinsic tryptophan fluorescence kinetics measurement applied to protein-protein complex during nucleotide hydrolysis. Outcome: no signal. Reason: low signal-to-noise ratio at physiological temperature and high background fluorescence from the binding partner
Considered and rejected
Considered and rejected: Rejected NMR titration and isothermal titration calorimetry (ITC) for measuring aqueous nanohoop-fullerene binding affinities due to low sensitivity (>10^6 M^-1) and precipitation artifacts.
Functionalized Carbon Nanohoops: Nitrogen-Doped Partial Belts, Macrocyclic Ligands, and The Inherent Strain That Affects Their Chemical Properties · Scholars' Bank
Solution conditions and extreme concentration requirements distort binding equilibrium or promote target oligomerization
Chemical additives like residual solubilizing polymers and free ligands can directly interfere with binding equilibrium or obscure binding activity. Additionally, requirements for high protein concentrations in titration assays can induce target dimerization or oligomerization rather than reporting on native monomer interactions.
Tried and failed
polymer-based membrane protein solubilisation applied to radioligand binding assays. Outcome: no signal. Reason: residual free polymer directly interfered with ligand binding, eliminating specific binding signal
Structural and functional study of vesicular acetylcholine transporter (VAChT) · Imperial
Tried and failed
dialysis degassing binding assay applied to measuring low-affinity anion protein binding. Outcome: no signal. Reason: variable baseline free ion concentrations and vessel leaks obscured ligand binding activity
Considered and rejected
Considered and rejected: Rejected equilibrium dialysis for soluble IAA binding assays due to high free-ligand background requiring unsafe and costly radiolabel concentrations.
THE MOLECULAR BIOLOGY OF PLANT GROWTH CONTROL · De Montfort Open Research Archive (DORA)
Tried and failed
titration calorimetry under limiting ligand conditions applied to measuring weak metal-ligand binding thermodynamics. Outcome: no signal. Reason: incomplete binding equilibrium without large excess ligand prevented quantitative product determination by spectroscopy
Considered and rejected
Considered and rejected: Traditional binding equilibrium and X-ray crystallographic approaches for mapping the TCA binding site were rejected due to the low-millimolar binding affinity
Modulation of eukaryotic topoisomerase II activity by naturally occurring small molecules · JScholarship
Considered and rejected
Considered and rejected: Rejected using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) for the benzophenanthridinone class (968) due to high protein concentration requirements where GAC forms dimers/tetramers rather than binding monomers.
THE ALLOSTERIC REGULATION OF GLUTAMINASE ENZYMES: DRIVING GLUTAMINE CATABOLISM IN CANCER CELLS · Cornell
Theoretical and sequential binding models fail to fit complex or multivalent interaction equilibria
Standard sequential binding models and thermodynamic predictions frequently fail to fit experimental titration curves when interacting systems exhibit multi-site, asymmetric, or multivalent binding. In addition, solubility limits and incomplete surface saturation prevent accurate kinetic parameter estimation in surface plasmon resonance and calorimetry experiments.
Tried and failed
surface plasmon resonance binding affinity modeling applied to fragment library screening on structured RNA. Outcome: did not converge. Reason: complex multi-site binding and solubility limits prevented reaching surface saturation needed for kinetic fitting
Tried and failed
predicting surface hybridization using thermodynamic binding models applied to nucleic acid microarray probe binding. Outcome: no signal. Reason: theoretical free energy and GC content did not correlate with observed surface hybridization intensity
Measuring the Effects of Viral RNA Structure on Capsid Self-Assembly · Harvard
Tried and failed
sequential multi-site binding model applied to isothermal titration calorimetry data. Outcome: did not converge. Reason: The model failed to adequately fit the experimental titration curve.
C2 domains of dysferlin and synaptotagmin-1: Structure and mechanics · Texas Tech
Tried and failed
Sequential binding models for ITC data fitting applied to protein-RNA homodimer binding isotherm analysis. Outcome: did not converge. Reason: Total concentration assumptions and sequential binding models failed to capture complex or asymmetric multivalent binding equilibria
A structure-based mechanism for recognition of oskar mRNA by Tropomyosin 1 · Harvard
Lost to a baseline
Equilibrium multivalent binding theory failed to accurately fit the steepness of adsorption for the strongest binder (Delta G0 = -17 kBT), requiring an empirical two-parameter logistic fit instead.
Left open by the authors
Problems the authors named and did not get to.
Left open
Test whether a simple cell or protein binding assay predicts loss of binding and in vivo transcytosis activity of antibody mutants. Blocker: Requires wet lab experiments with cell or protein binding assays and mutant antibodies
Left open
Perform in vitro binding assays between the RetS Dismed2 domain and mucin glycans to probe direct glycan-binding mechanism. Blocker: Requires a wet lab, recombinant protein purification, and in vitro glycan binding assays.
Left open
Test whether full-length BtszB or Btsz-CT binds G-actin and promotes actin assembly or disassembly in vitro. Blocker: Requires purified proteins and wet-lab in vitro actin polymerization/binding assays
Bitesize bundles F-actin and influences actin remodeling in syncytial Drosophila embryo development · MIT
Left open
Perform competitive displacement assays to verify receptor-mediated accumulation and binding of peptide-modified liposomes to metastatic breast cancer cells. Blocker: Requires a wet biology lab, cell cultures, and physical chemical/liposomal reagents.
The Stability Profiles of Novel Peptide Modified Liposomes Designed to Treat Metastatic Breast Cancer · WTAMU Repository
Left open
Investigate specific secretion and internalization mechanisms of cell-surface RNA-binding proteins in neurodegenerative disease and cancer models. Blocker: Requires wet lab biological experiments, disease cell lines, and molecular assay apparatus.
Cell-Surface RNA-Binding Proteins · Harvard
Left open
Test in vitro whether Sld3/7 forms a functional heterotetramer and preferentially binds Mcm2-7 double hexamers. Blocker: Requires wet lab biochemical assays, protein purification, and binding analysis
Single-molecule studies of the mechanism of eukaryotic helicase activation · MIT
Left open
Perform functional validation of increased VDR binding and activation in APOE2-expressing microglia using TF ChIP-seq, knockout, or overexpression assays. Blocker: Requires a wet lab and biological experimental assays (TF ChIP-seq, KO, overexpression)
Left open
Perform high-throughput experimental testing and library binding assays to validate the in vitro activity of computationally designed peptide binders. Blocker: Requires a wet biology laboratory and experimental assay infrastructure
Computational methods for the structure-based design of protein-binding peptides · MIT
Left open
Validate binding affinity of ambiguous or fluorescence-quenching MST hit compounds against G9a using surface plasmon resonance assays. Blocker: Requires a wet lab, surface plasmon resonance instrumentation, purified recombinant G9a protein, and physical compound samples
Left open
Identify additional hits from antibody libraries and characterize full IgG binding affinity using surface plasmon resonance. Blocker: Requires wet lab facilities, surface plasmon resonance equipment, and physical antibody libraries/samples
ENGINEERING THE HUMORAL RESPONSE TO GENERATE ANTIGEN-SPECIFIC ANTIBODIES · Cornell
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