Cell-Based Chemical Safety Assessment and Therapeutic Discovery Using Array-Based Sensors

Nanosensor-Enabled Detection and Identification of Intracellular Bacterial Infections in Macrophages

Opportunistic bacterial pathogens can evade the immune response by residing and reproducing within host immune cells, including macrophages. These intracellular infections provide reservoirs for pathogens that enhance the progression of infections and inhibit therapeutic strategies. Current sensing strategies for intracellular infections generally use immunosensing of specific biomarkers on the cell surface or polymerase chain reaction (PCR) of the corresponding nucleic acids, making detection difficult, time-consuming, and challenging to generalize. Intracellular infections can induce changes in macrophage glycosylation, providing a potential strategy for signature-based detection of intracellular infections. We report here the detection of bacterial infection in macrophages using a boronic acid (BA)-based pH-responsive polymer sensor array engineered to distinguish mammalian cell phenotypes by their cell surface glycosylation signatures. The sensor was able to discriminate between different infecting bacteria in minutes, providing a promising tool for diagnostic and screening applications.

Sensor Array-Enabled Identification of Drugs for Repolarization of Macrophages to Anti-Inflammatory Phenotypes

Macrophages are key components of the innate immune system that have essential functions in physiological processes and diseases. The phenotypic plasticity of macrophages allows cells to be polarized into a multidimensional spectrum of phenotypes, broadly classed as pro-inflammatory (M1) and anti-inflammatory (M2) states. Repolarization of M1 to M2 phenotypes alters the immune response to ameliorate autoimmune and inflammation-associated diseases. Detection of this repolarization, however, is challenging to execute in high-throughput applications. In this work, we demonstrate the ability of a single polymer fabricated to provide a six-channel sensor array that can determine macrophage polarization phenotypes. This sensing platform provides a sensitive and high-throughput tool for detecting drug-induced M1-to-M2 repolarization, allowing the identification of new therapeutic leads for inflammatory diseases. The ability of this sensor array to discriminate different M2 subtypes induced by drugs can also improve the efficacy evaluation of anti-inflammatory drugs and avoid adverse effects.

Inhibition of Tumor-Derived C-C Motif Chemokine Ligand 2 Expression Attenuates Tactile Allodynia in NCTC 2472 Fibrosarcoma-Inoculated Mice

Neuropathic pain associated with cancers is caused by tumor growth compressing and damaging nerves, which would also be enhanced by inflammatory factors through sensitizing nociceptor neurons. A troublesome hallmark symptom of neuropathic pain is hypersensitivity to innocuous stimuli, a condition known as "tactile allodynia", which is often refractory to NSAIDs and opioids. The involvement of chemokine CCL2 (monocyte chemoattractant protein-1) in cancer-evoked neuropathic pain is well established, but opinions remain divided as to whether CCL2 is involved in the production of tactile allodynia with tumor growth. In this study, we constructed Ccl2 knockout NCTC 2472 (Ccl2-KO NCTC) fibrosarcoma cells and conducted pain behavioral test using Ccl2-KO NCTC-implanted mice. Implantation of naïve NCTC cells around the sciatic nerves of mice produced tactile allodynia in the inoculated paw. Although the growth of Ccl2 KO NCTC-formed tumors was comparable to that of naïve NCTC-formed tumors, Ccl2-KO NCTC-bearing mice failed to show tactile pain hypersensitivity, suggesting the involvement of CCL2 in cancer-induced allodynia. Subcutaneous administration of controlled-release nanoparticles containing the CCL2 expression inhibitor NS-3-008 (1-benzyl-3-hexylguanidine) significantly attenuated tactile allodynia in naïve NCTC-bearing mice accompanied by a reduction of CCL2 content in tumor masses. Our present findings suggest that inhibition of CCL2 expression in cancer cells is a useful strategy to attenuate tactile allodynia induced by tumor growth. Development of a controlled-release system of CCL2 expression inhibitor may be a preventative option for the treatment of cancer-evoked neuropathic pain. SIGNIFICANCE STATEMENT: The blockade of chemokine/receptor signaling, particularly for C-C motif chemokine ligand 2 (CCL2) and its high-affinity receptor C-C chemokine receptor type 2 (CCR2), has been implicated to attenuate cancer-induced inflammatory and nociceptive pain. This study demonstrated that continuous inhibition of CCL2 production from cancer cells also prevents the development of tactile allodynia associated with tumor growth. Development of a controlled-release system of CCL2 expression inhibitor may be a preventative option for management of cancer-evoked tactile allodynia.

Identification of Proteins Using Supramolecular Gold Nanoparticle-Dye Sensor Arrays

The rapid detection of proteins is very important in the early diagnosis of diseases. Gold nanoparticles (AuNPs) can be engineered to bind biomolecules efficiently and differentially. Cross-reactive sensor arrays have high sensitivity for sensing proteins using differential interactions between sensor elements and bioanalytes. A new sensor array was fabricated using surface-charged AuNPs with dyes supramolecularly encapsulated into the AuNP monolayer. The fluorescence of dyes is partially quenched by the AuNPs and can be restored or further quenched due to the differential interactions between AuNPs with proteins. This sensing system enables the discrimination of proteins in both buffer and human serum, providing a potential tool for real-world disease diagnostics.

Direct discrimination of cell surface glycosylation signatures using a single pH-responsive boronic acid-functionalized polymer

Cell surface glycans serve fundamental roles in many biological processes, including cell-cell interaction, pathogen infection, and cancer metastasis. Cancer cell surface have alternative glycosylation to healthy cells, making these changes useful hallmarks of cancer. However, the diversity of glycan structures makes glycosylation profiling very challenging, with glycan 'fingerprints' providing an important tool for assessing cell state. In this work, we utilized the pH-responsive differential binding of boronic acid (BA) moieties with cell surface glycans to generate a high-content six-channel BA-based sensor array that uses a single polymer to distinguish mammalian cell types. This sensing platform provided efficient discrimination of cancer cells and readily discriminated between Chinese hamster ovary (CHO) glycomutants, providing evidence that discrimination is glycan-driven. The BA-functionalized polymer sensor array is readily scalable, providing access to new diagnostic and therapeutic strategies for cell surface glycosylation-associated diseases.