A Fiber Optic Interface Coupled to Nanosensors: Applications to Protein Aggregation and Organic Molecule Quantification

Abstract

The monitoring of therapeutic protein critical quality attributes such as aggregation is a long-standing challenge requiring low detection limits and multiplexing of different product parameters. However, general approaches for interfacing nanosensors to the biopharmaceutical process remain minimally explored to date. Herein, we design and fabricate a integrated fiber optic nanosensor element, measuring sensitivity, response time, and stability for applications to the rapid process monitoring. The fiber optic−nanosensor interface, or optode, consists of labelfree nIR fluorescent single-walled carbon nanotube transducers embedded within a protective yet porous hydrogel attached to the end of the fiber waveguide. The optode platform is shown to be capable of differentiating the aggregation status of human immunoglobulin G, reporting the relative fraction of monomers and dimer aggregates with sizes 5.6 and 9.6 nm, respectively, in under 5 min of analysis time. We introduce a lab-on-fiber design with potential for at-line monitoring with integration of 3D-printed miniaturized sensor tips having high mechanical flexibility. A parallel measurement of fluctuations in laser excitation allows for intensity normalization and significantly lower noise level (3.7 times improved) when using lower quality lasers, improving the cost effectiveness of the platform. As an application, we demonstrate the capability of the fully integrated lab-on-fiber system to rapidly monitor various bioanalytes including serotonin, norepinephrine, adrenaline, and hydrogen peroxide, in addition to proteins and their aggregation states. These results in total constitute an effective form factor for nanosensor-based transducers for applications in industrial process monitoring.

Species-independent analytical tools for next-generation agriculture

“…The fluorescent nanosensors described in the previous section can be easily interfaced within a fibre optic platform, creating an electrode-like or optode probe for the detection of local nutrients, pollutants and specific microorganisms in the soil. In this configuration, nanosensors are mounted at the tip of an optical fibre which performs both the excitation and signal collection for fluorescence monitoring, as we and others have shown recently 126,127 . The nanosensor-optode form factor has a high mechanical flexibility and can be compactly integrated into a portable detection platform that can utilize the same hardware as Raman spectroscopy.…”

Cellular lensing and near infrared fluorescent nanosensor arrays to enable chemical efflux cytometry

“…However, cellular populations are necessarily heterogeneous, and cellular therapies necessarily require characterization methods that are non-destructive and do not contaminate the cells themselves 15 , ruling out conventional flow cytometry that requires fluorescent labels 16 . Extending various types of nanosensors to statistically relevant numbers of living cells and organisms in a non-destructive manner remains unaddressed to date with the basic problem of nanosensors including interfacing strategy, signal-transducing mechanism, and mechanical robustness 17 .…”

Rapid SARS-CoV-2 Detection by Carbon Nanotube-Based Near-Infrared Nanosensors

“…Importantly, the SWCNT near-infrared emission is minimally absorbed and scattered by biomolecules ( 27 ), providing a readout that can penetrate optically occluded patient samples, thus eliminating the need for sample purification and processing that limit the throughput of other testing modes. Furthermore, SWCNTs offer facile incorporation into portable form factors such as immobilization in paper or hydrogels ( 29, 30 ) with detection of the nIR SWCNT signal by a raspberry pi system, of similar form factor to a smartphone ( 31 ).…”