Llama-derived single-domain antibodies for the detection of botulinum A neurotoxin

Single-Domain Antibody Multimers for Detection of Botulinum Neurotoxin Serotypes C, D, and Their Mosaics in Endopep-MS

Botulinum neurotoxins (BoNTs) are highly toxic proteins that require high-affinity immunocapture reagents for use in endopeptidase-based assays. Here, 30 novel and 2 earlier published llama single-domain antibodies (VHHs) against the veterinary-relevant BoNT serotypes C and D were yeast-produced. These VHHs recognized 10 independent antigenic sites, and many cross-reacted with the BoNT/DC and CD mosaic variants. As VHHs are highly suitable for genetically linking to increase antigen-binding affinity, 52 VHH multimers were produced and their affinity for BoNT/C, D, DC, and CD was determined. A selection of 15 multimers with high affinity (KD < 0.1 nM) was further shown to be resilient to a high salt wash that is used for samples from complex matrices and bound native BoNTs from culture supernatants as shown by Endopep-MS. High-affinity multimers suitable for further development of a highly sensitive Endopep-MS assay include four multimers that bind both BoNT/D and CD with KD of 14-99 pM, one multimer for BoNT/DC (65 pM) that also binds BoNT/C (75 pM), and seven multimers for BoNT/C (<1-19 pM), six of which also bind BoNT/DC with lower affinity (93-508 pM). In addition to application in diagnostic tests, these VHHs could be used for the development of novel therapeutics for animals or humans.

Surface Acoustic Wave Immunosensor for Detection of Botulinum Neurotoxin

A Love-type acoustic wave sensor (AT-cut quartz substrate, SiO2 guiding layer) with a center frequency of approximately 120 MHz was used to detect a simulant of pathogenic botulinum neurotoxin type A-recombinant of BoNT-A light chain-in liquid samples. The sensor was prepared by immobilizing monoclonal antibodies specific for botulinum neurotoxin via a thiol monolayer deposited on a gold substrate. Studies have shown that the sensor enables selective analyte detection within a few minutes. In addition, the sensor can be used several times (regeneration of the sensor is possible using a low pH buffer). Nevertheless, the detectability of the analyte is relatively low compared to other analytical techniques that can be used for rapid detection of botulinum neurotoxin. The obtained results confirm the operation of the proposed sensor and give hope for further development of this label-free technique for detecting botulinum neurotoxin.

Nanobodies: the Potential Application in Bacterial Treatment and Diagnosis

An infection caused by bacteria is one of the main factors that poses a threat to human health. A recent report from the World Health Organization (WHO) has highlighted that bacteria that cause blood infections have become increasingly drug-resistant. Therefore, it is crucial to research and develop new techniques for detecting and treating these infections. Since their discovery, nanobodies have exhibited numerous outstanding biological properties. They are easy to express, modify, and have high stability, robust permeability and low immunogenicity, all of which indicate their potential as a substitute. Nanobodies have been utilized in a variety of studies on viruses and cancer. This article primarily focuses on nanobodies and introduces their characteristics and application in the diagnosis and treatment of bacterial infections.

rAAV expressing recombinant neutralizing antibody for the botulinum neurotoxin type A prophylaxis

Botulinum neurotoxin (BoNT) is one of the most dangerous bacterial toxins and a potential biological weapon component. BoNT mechanism of pathological action is based on inhibiting the release of neurotransmitters from nerve endings. To date, anti-BoNT therapy is reduced to the use of horse hyperimmune serum, which causes many side effects, as well as FDA-approved drug BabyBig which consists of human-derived anti-BoNT antibodies (IgG) for infant botulinum treatment. Therapeutics for botulism treatment based on safer monoclonal antibodies are undergoing clinical trials. In addition, agents have been developed for the specific prevention of botulism, but their effectiveness has not been proved. In this work, we have obtained a recombinant adeno-associated virus (rAAV-B11-Fc) expressing a single-domain antibody fused to the human IgG Fc-fragment (B11-Fc) and specific to botulinum toxin type A (BoNT/A). We have demonstrated that B11-Fc antibody, expressed via rAAV-B11-Fc treatment, can protect animals from lethal doses of botulinum toxin type A, starting from day 3 and at least 120 days after administration. Thus, our results showed that rAAV-B11-Fc can provide long-term expression of B11-Fc-neutralizing antibody in vivo and provide long-term protection against BoNT/A intoxication. Consequently, our study demonstrates the applicability of rAAV expressing protective antibodies for the prevention of intoxication caused by botulinum toxins.

Phage-based technologies for highly sensitive luminescent detection of foodborne pathogens and microbial toxins: A review

Foodborne pathogens and microbial toxins are the main causes of foodborne illness. However, trace pathogens and toxins in foods are difficult to detect. Thus, techniques for their rapid and sensitive identification and quantification are urgently needed. Phages can specifically recognize and adhere to certain species of microbes or toxins due to molecular complementation between capsid proteins of phages and receptors on the host cell wall or toxins, and thus they have been successfully developed into a detection platform for pathogens and toxins. This review presents an update on phage-based luminescent detection technologies as well as their working principles and characteristics. Based on phage display techniques of temperate phages, reporter gene detection assays have been designed to sensitively detect trace pathogens by luminous intensity. By the host-specific lytic effects of virulent phages, enzyme-catalyzed chemiluminescent detection technologies for pathogens have been exploited. Notably, these phage-based luminescent detection technologies can discriminate viable versus dead microbes. Further, highly selective and sensitive immune-based assays have been developed to detect trace toxins qualitatively and quantitatively via antibody analogs displayed by phages, such as phage-ELISA (enzyme-linked immunosorbent assay) and phage-IPCR (immuno-polymerase chain reaction). This literature research may lead to novel and innocuous phage-based rapid detection technologies to ensure food safety.

Camelid VHHs Fused to Human Fc Fragments Provide Long Term Protection Against Botulinum Neurotoxin A in Mice

The bacterium Clostridium botulinum is the causative agent of botulism-a severe intoxication caused by botulinum neurotoxin (BoNT) and characterized by damage to the nervous system. In an effort to develop novel C. botulinum immunotherapeutics, camelid single-domain antibodies (sdAbs, VHHs, or nanobodies) could be used due to their unique structure and characteristics. In this study, VHHs were produced using phage display technology. A total of 15 different monoclonal VHHs were selected based on their comlementarity-determining region 3 (CDR3) sequences. Different toxin lethal dose (LD50) challenges with each selected phage clone were conducted in vivo to check their neutralizing potency. We demonstrated that modification of neutralizing VHHs with a human immunoglobulin G (IgG)1 Fc (fragment crystallizable) fragment (fusionbody, VHH-Fc) significantly increased the circulation time in the blood (up to 14 days). At the same time, VHH-Fc showed the protective activity 1000 times higher than monomeric form when challenged with 5 LD50. Moreover, VHH-Fcs remained protective even 14 days after antibody administration. These results indicate that this VHH-Fc could be used as an effective long term antitoxin protection against botulinum type A.

Application of Virus Targeting Nanocarrier Drug Delivery System in Virus-Induced Central Nervous System Disease Treatment

Virus-induced central nervous system (CNS) diseases represent a significant burden to animal health worldwide. The difficulty in treating these diseases is mainly attributable to the elaborate barrier system, which limits the transport of drugs to the infected sites. Therefore, it is necessary to develop smart delivery technologies for treatment of these diseases. In the study, viral nervous necrosis disease was studied as a model to evaluate the feasibility of multiwalled carbon nanotubes (MWCNTs) conjugated with virus-specific nanobody and antiviral drug for targeted therapy of virus-induced CNS diseases. The virus (named as PGNNV) was isolated, identified and purified from diseased grouper. A naïve phage-displayed alpaca nanobody library was constructed, and the purified PGNNV was used for biopanning of PGNNV-specific nanobody from the library. The targeted delivery system based on MWCNTs conjugated with polyethylenimine, ribavirin, and PGNNV-specific nanobody was constructed and designated as MWCNTs-PEI-R-Nb. Targeting ability and treatment effects of the MWCNTs-PEI-R-Nb were checked both in vitro and in vivo. MWCNTs-PEI-R-Nb showed an increasing distribution in PGNNV-infected cells, and an obvious accumulation in the brain of PGNNV-infected zebrafish larvae. MWCNTs-PEI-R-Nb also showed a strong anti-PGNNV ability both in vitro and in vivo. The mortality of larvae treated with MWCNTs-PEI-R-Nb (equivalent to 100 mg/L ribavirin) was 27% during 10 days post infection, whereas it was 100% for the control group. The results so far indicate that MWCNTs conjugated with antiviral drugs and viral-specific antibody are effective means for virus-induced CNS disease targeted therapy.

Isolation and characterization of malaria PfHRP2 specific VNAR antibody fragments from immunized shark phage display library

BACKGROUND

Malaria rapid diagnostic tests (RDTs) represent an important antibody based immunoassay platform. Unfortunately, conventional monoclonal antibodies are subject to degradation shortening shelf lives of RDTs. The variable region of the receptor (VNAR) from shark has a potential as alternative to monoclonal antibodies in RDTs due to high thermal stability.

METHODS

In this study, new binders derived from shark VNAR domains library were investigated. Following immunization of a wobbegong shark (Orectolobus ornatus) with three recombinant malaria biomarker proteins (PfHRP2, PfpLDH and Pvaldolase), a single domain antibody (sdAb) library was constructed from splenocytes. Target-specific VNAR phage were isolated by panning. One specific clone was selected for expression in Escherichia coli expression system, and study of binding reactivity undertaken.

RESULTS

The primary VNAR domain library possessed a titre of 1.16 × 106 pfu/mL. DNA sequence analysis showed 82.5% of isolated fragments appearing to contain an in-frame sequence. After multiple rounds of biopanning, a highly dominant clone specific to PfHRP2 was identified and selected for protein production in an E. coli expression system. Biological characterization showed the recombinant protein expressed in periplasmic has better detection sensitivity than that of cytoplasmic proteins. Assays of binding activity indicated that its reactivity was inferior to the positive control mAb C1-13.

CONCLUSIONS

Target-specific bacteriophage VNARs were successfully isolated after a series of immunization, demonstrating that phage display technology is a useful tool for selection of antigen binders. Generation of new binding reagents such as VNAR antibodies that specifically recognize the malaria biomarkers represents an appealing approach to improve the performance of RDTs.

Rapid and Sensitive Detection of Staphylococcal Enterotoxin B by Recombinant Nanobody Using Phage Display Technology

Staphylococcal enterotoxin B, from Staphylococcus aureus (S. aureus), is one of the most potent bacterial superantigens with profound toxic effects on the immune system. It is associated with food poisoning, toxic shock, atopic dermatitis, asthma, and nasal polyps in humans. The current diagnostic methods for staphylococcal enterotoxin are mainly based on traditional monoclonal antibodies which hardly meet the requirements for clinical applications, and hybridoma clones lose their ability to secrete antibodies during time. The present study investigates the development of a novel, highly specific, low-cost, and sensitive nanobody capable of being used in immunoassays for Staphylococcal enterotoxin B (SEB) detection in suspicious foods. For this purpose, Camelus dromedarius was immunized against SEB toxin. After obtaining acceptable titration, a high-quality phage display nanobody library (4 × 10¹⁰ PFU/ml) was constructed. High-affinity SEB-specific nanobodies were retrieved from constructed libraries. After phage rescue and five round of biopanning, clone screening was performed by phage ELISA. Recombinant nanobodies which were expressed from C7 and C21 clone showed the highest affinity for SEB. The presence of high quality and pure nanobody band at ~ 15 kDa was confirmed by SDS-PAGE and western blotting. The affinity constant which was measured by ELISA was calculated to be around 10^-9 M. The results suggest that the proposed detection method by nanobodies is an alternative diagnostic tool enabling a rapid, inexpensive, and specific detection of the SEB.

Single Domain Antibodies as New Biomarker Detectors

Biomarkers are defined as indicators of biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. Biomarkers have been widely used for early detection, prediction of response after treatment, and for monitoring the progression of diseases. Antibodies represent promising tools for recognition of biomarkers, and are widely deployed as analytical tools in clinical settings. For immunodiagnostics, antibodies are now exploited as binders for antigens of interest across a range of platforms. More recently, the discovery of antibody surface display and combinatorial chemistry techniques has allowed the exploration of new binders from a range of animals, for instance variable domains of new antigen receptors (V_NAR) from shark and variable heavy chain domains (V_HH) or nanobodies from camelids. These single domain antibodies (sdAbs) have some advantages over conventional murine immunoglobulin owing to the lack of a light chain, making them the smallest natural biomarker binders thus far identified. In this review, we will discuss several biomarkers used as a means to validate diseases progress. The potential functionality of modern singe domain antigen binders derived from phylogenetically early animals as new biomarker detectors for current diagnostic and research platforms development will be described.

Centrifugal microfluidic platform for ultrasensitive detection of botulinum toxin

We present an innovative centrifugal microfluidic immunoassay platform (SpinDx) to address the urgent biodefense and public health need for ultrasensitive point-of-care/incident detection of botulinum toxin. The simple, sample-to-answer centrifugal microfluidic immunoassay approach is based on binding of toxins to antibody-laden capture particles followed by sedimentation of the particles through a density-media in a microfluidic disk and quantification by laser-induced fluorescence. A blind, head-to-head comparison study of SpinDx versus the gold-standard mouse bioassay demonstrates 100-fold improvement in sensitivity (limit of detection = 0.09 pg/mL), while achieving total sample-to-answer time of <30 min with 2-μL required volume of the unprocessed sample. We further demonstrate quantification of botulinum toxin in both exogeneous (human blood and serum spiked with toxins) and endogeneous (serum from mice intoxicated via oral, intranasal, and intravenous routes) samples. SpinDx can analyze, without any sample preparation, multiple sample types including whole blood, serum, and food. It is readily expandable to additional analytes as the assay reagents (i.e., the capture beads and detection antibodies) are disconnected from the disk architecture and the reader, facilitating rapid development of new assays. SpinDx can also serve as a general-purpose immunoassay platform applicable to diagnosis of other conditions and diseases.

Immunoreaction of a recombinant nanobody from camelid single domain antibody fragment with Acinetobacter baumannii

BACKGROUND

Acinetobacter baumannii, an important nosocominal pathogen, causes various human infections like meningitis, bacteremia and pneumonia. The aim of this study was to produce nanobodies derived from camel heavy chain antibodies (HcAb) against a conserved region of the biofilm associated protein (Bap) of A. baumannii, by phage display technique.

METHODS

A camel was immunized with the purified recombinant protein expressed from the conserved region of Bap and polyclonal antibody production was confirmed by ELISA. After RNA extraction from peripheral lymphocytes, cDNA was prepared and a phagemid library was constructed.

RESULTS

Phage particles encoding nanobodies were produced by infecting transformed cells with a M13K07 helper phage. A total of six panning rounds were performed to select high affinity clones. Screening of high affinity monoclonal nanobodies was performed using phage-ELISA. A clone with the highest absorption in monoclonal phage-ELISA was selected for soluble expression of the desired nanobody.

CONCLUSIONS

This is the first report on the expression and production of nanobodies against Bap. Increasing trends of drug resistance have shifted the focus to the role of antibodies in diagnosis and treatment of human diseases. Similarities of the produced VHH to human VH, makes the role of this nanobody promising in immunotherapy.

Nanoporous membrane based impedance sensors to detect the enzymatic activity of botulinum neurotoxin A

Botulinum neurotoxins are among the most potent toxic bacterial proteins for humans and there is a great need to develop simple, rapid and sensitive methods for toxin detection and protease activity quantification in field deployment. In this paper, a nanoporous membrane based impedance sensor was developed to monitor the activity of the BoNT serotype A light chain protease (LcA). Synaptosomal-associated protein 25 (SNAP-25) was first immobilized inside nanopore walls via silane linkers. BoNT LcA was then injected over the nanoporous membrane substrate sensor and specifically cleaved SNAP-25. The cleavage activity could be monitored by measuring impedance signals across nanoporous membranes which represented the nanopore blockage degree. This initial device could achieve a 500 pM LcA detection limit within 25 minutes.

Botulinum neurotoxin: where are we with detection technologies?

Because of its high toxicity, botulinum neurotoxin (BoNT) poses a significant risk to humans and it represents a possible biological warfare agent. Nevertheless, BoNT serotypes A and B are considered an effective treatment for a variety of neurological disorders. The growing applicability of BoNT as a drug, and its potential use as a biological threat agent, highlight the urgent need to develop sensitive detection assays and therapeutic counter measures. In the last decade, significant progress has been made in BoNT detection technologies but none have fully replaced the mouse lethality assay, the current "gold standard". Recently, new advances in robotics and the availability of new reagents have allowed development of methods for rapid toxin analysis. These technologies while promising need further refinement.

Biotemplating rod-like viruses for the synthesis of copper nanorods and nanowires

Background

In the past decade spherical and rod-like viruses have been used for the design and synthesis of new kind of nanomaterials with unique chemical positioning, shape, and dimensions in the nanosize regime. Wild type and genetic engineered viruses have served as excellent templates and scaffolds for the synthesis of hybrid materials with unique properties imparted by the incorporation of biological and organic moieties and inorganic nanoparticles. Although great advances have been accomplished, still there is a broad interest in developing reaction conditions suitable for biological templates while not limiting the material property of the product.

Results

We demonstrate the controlled synthesis of copper nanorods and nanowires by electroless deposition of Cu on three types of Pd-activated rod-like viruses. Our aqueous solution-based method is scalable and versatile for biotemplating, resulting in Cu-nanorods 24–46 nm in diameter as measured by transmission electron microscopy. Cu²⁺ was chemically reduced onto Pd activated tobacco mosaic virus, fd and M13 bacteriophages to produce a complete and uniform Cu coverage. The Cu coating was a combination of Cu⁰ and Cu₂O as determined by X- ray photoelectron spectroscopy analysis. A capping agent, synthesized in house, was used to disperse Cu-nanorods in aqueous and organic solvents. Likewise, reactions were developed to produce Cu-nanowires by metallization of polyaniline-coated tobacco mosaic virus.

Conclusions

Synthesis conditions described in the current work are scalable and amenable for biological templates. The synthesized structures preserve the dimensions and shape of the rod-like viruses utilized during the study. The current work opens the possibility of generating a variety of nanorods and nanowires of different lengths ranging from 300 nm to micron sizes. Such biological-based materials may find ample use in nanoelectronics, sensing, and cancer therapy.

Llama-derived single domain antibodies specific for Abrus agglutinin

Llama derived single domain antibodies (sdAb), the recombinantly expressed variable heavy domains from the unique heavy-chain only antibodies of camelids, were isolated from a library derived from llamas immunized with a commercial abrin toxoid preparation. Abrin is a potent toxin similar to ricin in structure, sequence and mechanism of action. The selected sdAb were evaluated for their ability to bind to commercial abrin as well as abrax (a recombinant abrin A-chain), purified abrin fractions, Abrus agglutinin (a protein related to abrin but with lower toxicity), ricin, and unrelated proteins. Isolated sdAb were also evaluated for their ability to refold after heat denaturation and ability to be used in sandwich assays as both capture and reporter elements. The best binders were specific for the Abrus agglutinin, showing minimal binding to purified abrin fractions or unrelated proteins. These binders had sub nM affinities and regained most of their secondary structure after heating to 95 °C. They functioned well in sandwich assays. Through gel analysis and the behavior of anti-abrin monoclonal antibodies, we determined that the commercial toxoid preparation used for the original immunizations contained a high percentage of Abrus agglutinin, explaining the selection of Abrus agglutinin binders. Used in conjunction with anti-abrin monoclonal and polyclonal antibodies, these reagents can fill a role to discriminate between the highly toxic abrin and the related, but much less toxic, Abrus agglutinin and distinguish between different crude preparations.

A broad set of different llama antibodies specific for a 16 kDa heat shock protein of Mycobacterium tuberculosis

Background

Recombinant antibodies are powerful tools in engineering of novel diagnostics. Due to the small size and stable nature of llama antibody domains selected antibodies can serve as a detection reagent in multiplexed and sensitive assays for M. tuberculosis.

Methodology/Principal Findings

Antibodies for Mycobacterium tuberculosis (M. tb) recognition were raised in Alpaca, and, by phage display, recombinant variable domains of heavy-chain antibodies (VHH) binding to M. tuberculosis antigens were isolated. Two phage display selection strategies were followed: one direct selection using semi-purified protein antigen, and a depletion strategy with lysates, aiming to avoid cross-reaction to other mycobacteria. Both panning methods selected a set of binders with widely differing complementarity determining regions. Selected recombinant VHHs were produced in E. coli and shown to bind immobilized lysate in direct Enzymelinked Immunosorbent Assay (ELISA) tests and soluble antigen by surface plasmon resonance (SPR) analysis. All tested VHHs were specific for tuberculosis-causing mycobacteria (M. tuberculosis, M. bovis) and exclusively recognized an immunodominant 16 kDa heat shock protein (hsp). The highest affinity VHH had a dissociation constant (KD) of 4×10⁻¹⁰ M.

Conclusions/Significance

A broad set of different llama antibodies specific for 16 kDa heat shock protein of M. tuberculosis is available. This protein is highly stable and abundant in M. tuberculosis. The VHH that detect this protein are applied in a robust SPR sensor for identification of tuberculosis-causing mycobacteria.

Isolation of a highly thermal stable lama single domain antibody specific for Staphylococcus aureus enterotoxin B

Background

Camelids and sharks possess a unique subclass of antibodies comprised of only heavy chains. The antigen binding fragments of these unique antibodies can be cloned and expressed as single domain antibodies (sdAbs). The ability of these small antigen-binding molecules to refold after heating to achieve their original structure, as well as their diminutive size, makes them attractive candidates for diagnostic assays.

Results

Here we describe the isolation of an sdAb against Staphyloccocus aureus enterotoxin B (SEB). The clone, A3, was found to have high affinity (Kd = 75 pM) and good specificity for SEB, showing no cross reactivity to related molecules such as Staphylococcal enterotoxin A (SEA), Staphylococcal enterotoxin D (SED), and Shiga toxin. Most remarkably, this anti-SEB sdAb had an extremely high Tm of 85°C and an ability to refold after heating to 95°C. The sharp Tm determined by circular dichroism, was found to contrast with the gradual decrease observed in intrinsic fluorescence. We demonstrated the utility of this sdAb as a capture and detector molecule in Luminex based assays providing limits of detection (LODs) of at least 64 pg/mL.

Conclusion

The anti-SEB sdAb A3 was found to have a high affinity and an extraordinarily high Tm and could still refold to recover activity after heat denaturation. This combination of heat resilience and strong, specific binding make this sdAb a good candidate for use in antibody-based toxin detection technologies.

Biotechnological applications of recombinant single-domain antibody fragments

BACKGROUND

Single-domain antibody fragments possess structural features, such as a small dimension, an elevated stability, and the singularity of recognizing epitopes non-accessible for conventional antibodies that make them interesting for several research and biotechnological applications.

RESULTS

The discovery of the single-domain antibody's potentials has stimulated their use in an increasing variety of fields. The rapid accumulation of articles describing new applications and further developments of established approaches has made it, therefore, necessary to update the previous reviews with a new and more complete summary of the topic.

CONCLUSIONS

Beside the necessary task of updating, this work analyses in detail some applicative aspects of the single-domain antibodies that have been overseen in the past, such as their efficacy in affinity chromatography, as co-crystallization chaperones, protein aggregation controllers, enzyme activity tuners, and the specificities of the unconventional single-domain fragments.

Monitoring botulinum neurotoxin a activity with peptide-functionalized quantum dot resonance energy transfer sensors

Botulinum neurotoxins (BoNTs) are extremely potent bacterial toxins that contaminate food supplies along with having a high potential for exploitation as bioterrorism agents. There is a continuing need to rapidly and sensitively detect exposure to these toxins and to verify their active state, as the latter directly affects diagnosis and helps provide effective treatments. We investigate the use of semiconductor quantum dot (QD)-peptide Förster resonance energy transfer (FRET) assemblies to monitor the activity of the BoNT serotype A light chain protease (LcA). A modular LcA peptide substrate was designed and optimized to contain a central LcA recognition/cleavage region, a unique residue to allow labeling with a Cy3 acceptor dye, an extended linker-spacer sequence, and a terminal oligohistidine that allows for final ratiometric peptide-QD-self-assembly. A number of different QD materials displaying charged or PEGylated surface-coatings were evaluated for their ability to self-assemble dye-labeled LcA peptide substrates by monitoring FRET interactions. Proteolytic assays were performed utilizing either a direct peptide-on-QD format or alternatively an indirect pre-exposure of peptide to LcA prior to QD assembly. Variable activities were obtained depending on QD materials and formats used with the most sensitive pre-exposure assay result demonstrating a 350 pM LcA limit of detection. Modeling the various QD-peptide sensor constructs provided insight into how the resulting assembly architecture influenced LcA recognition interactions and subsequent activity. These results also highlight the unique roles that both peptide design and QD features, especially surface-capping agents, contribute to overall sensor activity.