Nanoscale field-effect transistors (FETs) represent a unique platform for real time, label-free transduction of biochemical signals with unprecedented sensitivity and spatiotemporal resolution, yet their translation toward practical biomedical applications remains challenging. Herein, we demonstrate the potential to overcome several key limitations of traditional FET sensors by exploiting bioactive hydrogels as the gate material. Spatially defined photopolymerization is utilized to achieve selective patterning of polyethylene glycol on top of individual graphene FET devices, through which multiple biospecific receptors can be independently encapsulated into the hydrogel gate. The hydrogel-mediated integration of penicillinase was demonstrated to effectively catalyze enzymatic reaction in the confined microenvironment, enabling real time, label-free detection of penicillin down to 0.2 mM. Multiplexed functionalization with penicillinase and acetylcholinesterase has been demonstrated to achieve highly specific sensing. In addition, the microenvironment created by the hydrogel gate has been shown to significantly reduce the nonspecific binding of nontarget molecules to graphene channels as well as preserve the encapsulated enzyme activity for at least one week, in comparison to free enzymes showing significant signal loss within one day. This general approach presents a new biointegration strategy and facilitates multiplex detection of bioanalytes on the same platform, which could underwrite new advances in healthcare research.
Three experiments were carried out to determine absolute and differential thresholds for vibrotactile forces and external influences in the frequency range of 5 to 1,000 Hz at the tip of the index finger. Differential thresholds were obtained for reference stimuli of 0.5, 0.25 N, and near the individual threshold. Frequency, temperature, age, fingertip size, and contact force were investigated as parameters in a full-factorial design. Experiments were conducted with at least 27 subjects and a 1up-2down staircase procedure with 3IFC paradigm. We find absolute thresholds ranging from 1.7 to 19 mN with the lowest threshold at 320 Hz. Weber fractions from 18 to 41 dB are found near the absolute threshold. For larger references, they range from 4.9 to 23 dB. ANOVA finds frequency as significant medium effect for both absolute and differential thresholds. Results imply impact of age on the absolute threshold, but no effect of motor skill, temperature, fingertip size, and contact force. Differential thresholds are affected by frequency only, which is attributed to saturation effects of the Pacinian channel. Fingertip size and motor skill are not able to explain effects on thresholds and the interpersonal variance. Results of this work are intended as requirement source for the design of task-specific haptic interfaces.
Immunoglobulin G (IgG) has served as a traditional framework for antibody-based biology, and engineering approaches for creating multispecific therapeutics have greatly expanded its applicability. Despite these developments, there are limits to the functionality of IgG with respect to effector cells that can be activated and paratope valency that can be obtained. Other Ig isotypes have distinct functions that can engage and activate different effector cells, and some can be found naturally in higher-order assemblies. In an effort to expand the repertoire of multispecific designs for other antibody isotypes, we present here engineering of the first heterodimeric IgA Fc that can be produced at high purity with native IgA-like thermal stability. The crystal structure confirmed the accuracy of the in silico model used for engineering and that the mutations introduced at the CH3 interface do not perturb the overall IgA Fc structure. Affinity measurements and on-cell neutrophil binding demonstrated that the heterodimeric IgA Fc retains the ability to bind FcαRI, an important prerequisite for IgA-based therapeutics designed to interact with effector cells, such as neutrophils. Given the ability of IgA antibodies to multimerize via interaction with the J-chain, the designs presented here could also be used to generate multispecific, multimeric scaffolds that leverage valency to increase clustering and specificity via avidity. Taken together, the newly developed heterodimeric IgA Fc platform allows for the development of novel, multifunctional, and multimeric molecules that have the potential to transform the next generation of antibody therapeutics. Abbreviations CE-SDS: capillary electrophoresis sodium dodecyl sulfate; DSC: differential scanning calorimetry; FACS: fluorescence-activated cell sorting; FSA: full-sized antibody; Her2: human epidermal growth factor receptor 2; MFI: mean fluorescent intensity; OAA: one-armed antibody; PBS: phosphate-buffered saline; PDB: Protein Data Bank; SEC: size-exclusion chromatography; prepSEC (preparative SEC); RMSD: root-mean-square deviation; RU: resonance units; SPR: surface plasmon resonance; TAA: tumor-associated antigen; WT: wild-type.
CD3-bispecific T cell engager (TCE) therapies have exhibited clinical utility against hematological malignancies, but successes in solid tumor indications have been limited. Compared to heme malignancies, treatment of solid tumors is hindered by immunosuppressed microenvironments that can be refractory to traditional CD3-bispecific TCEs. Immunosuppression in the tumor microenvironment limits treatment responses in part due to the expression of inhibitory immune checkpoints, such as PD-1 on exhausted T cells and PD-L1 on tumor cells. To improve T cell responses and anti-tumor activity in immunosuppressed solid tumors, we generated trispecific TCE antibodies (Abs) that target a tumor associated antigen (TAA), CD3 and PD-L1 (via a PD1 moiety) to stimulate tumor-directed T cell killing and checkpoint blockade at the tumor site. In this engineering approach we harnessed the flexibility of our AzymetricTM technology to screen multiple antibody formats, geometries, paratopes, and PD-1 domain affinities in parallel. We screened the TriTCE CPI antibodies, targeting different TAAs, for tumor-directed T cell cytotoxicity and CPI activity on TAA+PD-L1+ and TAA-PD-L1+ tumor cells. We identified multiple TriTCE CPI Abs that induced potent TAA-dependent T cell killing of TAA+PD-L1+, but not TAA-PD-L1+, tumor cells. Evaluation of CPI using a PD-1/PD-L1 checkpoint reporter gene assay identified antibody formats that stimulated simultaneous TAA dependent T cell engagement and enhanced checkpoint inhibition superior to bispecific Ab plus anti-PD-L1 Ab combination treatments. Additionally, in a human PBMC-engrafted xenograft model, TriTCE CPI Abs showed increased anti-tumor activity compared to a bispecific Ab control +/- anti-PD-L1 Ab treatment. Furthermore, the benefits of increased anti-tumor activity and CPI was observed across multiple TriTCE CPI Abs targeting different TAAs. We generated multiple TriTCE CPI Abs that combine tumor-dependent T cell cytotoxicity with checkpoint blockade, which may translate to improved T cell responses in immunosuppressed solid tumors. The evaluation of multiple Ab formats, geometries and paratope affinities allowed for optimization of TAA-dependent cytotoxicity and CPI to identify Abs with enhanced anti-tumor activity and superior site-specific CPI, key factors that may contribute to a wide therapeutic index and improved clinical outcomes. Citation Format: Maya C. Poffenberger, Meghan M. Verstraete, Anna Von Rossum, Patricia Zwierzchowski, Matteo Zago, Veronica Luu, Sifa Arrafi, Siran Cao, Harsh Pratap, Chayne L. Piscitelli, Nina E. Weisser, Thomas Spreter von Kreudenstein. TriTCE CPI, next generation trispecific T cell engagers with integrated checkpoint inhibition (CPI) for the treatment of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2982.
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