Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Grogan, Catherine; Florea, Larisa; Koprivica, Slavica; Scarmagnani, Silvia; O’Neill, Luke A.J.; Lyng, Fiona M.; Pedreschi, Fran; Benito‐Lopez, Fernando; Raiteri, Roberto

doi:10.1016/j.snb.2016.06.108

Cited by 17 publications

(20 citation statements)

References 45 publications

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“…Previous work tested the response of the silicon microcantilevers functionalized with SP on the silicon side of the microcantilevers, monitoring only the change in state from SP to MC and without using baseline subtraction methods [44]. This earlier work showed an upward deflection response of the functionalized microcantilever on exposure to UV due to the SP changing state to the MC form.…”

Section: Photo-induced Microcantilever Deflectionsmentioning

confidence: 99%

“…Consequently, the microcantilever tends to reduce its area, i.e., bending in the opposite direction ( Figure 4 and the schematic representation in Figure 3). The magnitude of the stress values presented will depend on the surface density of the photochromic molecules [35,44]. Tests were also carried out to determine the ability of SP-functionalized microcantilevers to detect the reversibility of the SP-MC transition.…”

Section: Photo-induced Microcantilever Deflectionsmentioning

confidence: 99%

“…The significantly different physico-chemical properties between SP and MC allow for the utilization of SP in a wide variety of applications, such as switchable photo-induced polarity sensors [31], volume change actuators [32][33][34] and wettability modulators [35], as well as for photo-control of binding/release of ions [36][37][38][39], cell adhesion [40] and membrane permeability [41]. Moreover, these molecules can be used to tune surface morphology [33], mechanical properties [42,43] and surface stress [24,44]. Therefore, the combination of microcantilever sensors and SP molecules could generate new types of sensors that synergistically combine the molecular sensing and binding capabilities of the SP-MC pair within a flexible and versatile sensing technology such as the microcantilevers sensors.…”

mentioning

confidence: 99%

“…Therefore, the combination of microcantilever sensors and SP molecules could generate new types of sensors that synergistically combine the molecular sensing and binding capabilities of the SP-MC pair within a flexible and versatile sensing technology such as the microcantilevers sensors. There is an increased interest in attaching molecular switches, such as SP, to thin films, as they allow for the conversion of molecular response to control, for example, electronic [45], optical [45], wettability [35] and chemosensing properties of materials [45].Previous work by this group focused on demonstrating the capability of silicon microcantilever sensors to detect the unidirectional conformation change from SP to MC, in the case of Si-bonded self-assembled monolayers (SAMs) and polymeric brushes as a proof of concept [44]. Although successful, several drawbacks such as the inhomogeneity of the generated layer and the tedious coating protocol (e.g., polymer brushes) prevented this technology from being further investigated.…”

mentioning

confidence: 99%

“…Previous work by this group focused on demonstrating the capability of silicon microcantilever sensors to detect the unidirectional conformation change from SP to MC, in the case of Si-bonded self-assembled monolayers (SAMs) and polymeric brushes as a proof of concept [44]. Although successful, several drawbacks such as the inhomogeneity of the generated layer and the tedious coating protocol (e.g., polymer brushes) prevented this technology from being further investigated.…”

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confidence: 99%

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Silicon Microcantilever Sensors to Detect the Reversible Conformational Change of a Molecular Switch, Spiropyan

Grogan

Amarandei

Lawless

et al. 2020

Sensors

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The high sensitivity of silicon microcantilever sensors has expanded their use in areas ranging from gas sensing to bio-medical applications. Photochromic molecules also represent promising candidates for a large variety of sensing applications. In this work, the operating principles of these two sensing methods are combined in order to detect the reversible conformational change of a molecular switch, spiropyran. Thus, arrays of silicon microcantilever sensors were functionalized with spiropyran on the gold covered side and used as test microcantilevers. The microcantilever deflection response was observed, in five sequential cycles, as the transition from the spiropyran (SP) (CLOSED) to the merocyanine (MC) (OPEN) state and vice-versa when induced by UV and white light LED sources, respectively, proving the reversibility capabilities of this type of sensor. The microcantilever deflection direction was observed to be in one direction when changing to the MC state and in the opposite direction when changing back to the SP state. A tensile stress was induced in the microcantilever when the SP to MC transition took place, while a compressive stress was observed for the reverse transition. These different type of stresses are believed to be related to the spatial conformational changes induced in the photochromic molecule upon photo-isomerisation.Sensors 2020, 20, 854 2 of 12 areas ranging from gas, humidity and thermal sensing to novel applications in microbiology, genomics and cancer detection [9][10][11][12][13][14][15]. Innovative microcantilever coatings include polymer brushes-based on phenylboronic acid which have been used to detect glucose binding events [15] and graphene oxide (GO) thin films for high-sensitivity humidity sensing [16]. Other examples involve the use of microcantilever sensors for detection of various diseases through, for example, antibody-antigen interactions for the detection of disease-related C-reactive proteins or for the screening of heart-related diseases by using cardiomyocytes functionalized microcantilevers [17][18][19]. Different fabrication methods for microcantilevers as well as the range of available modification methods in the substrate and sensing layer allow for the realization of different types of cantilever-based sensors [20,21]. An improvement in microcantilevers sensor efficiency of the n-type over p-type silicon cantilevers was demonstrated, and this effect was explained by their greater piezoresistive coefficient [20]. Examples include micromachined silicon cantilever paddle sensors which can be used in high flow rate gas sensing [20,21], and resonant cantilevers for pressure sensing [22].Spiropyrans (SP) are one of the most popular families of photochromic molecules [23,24]. Upon irradiation with UV light, the orthogonal SP isomer converts to the planar merocyanine (MC) form due to the photo-cleavage of the C spiro -O bond. The MC isomer shows a strong absorption band in the visible region due to its conjugation. When the MC is exposed to visible light, the structu...

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Section: Photo-induced Microcantilever Deflectionsmentioning

confidence: 99%

Section: Photo-induced Microcantilever Deflectionsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Silicon Microcantilever Sensors to Detect the Reversible Conformational Change of a Molecular Switch, Spiropyan

Grogan

Amarandei

Lawless

et al. 2020

Sensors

Self Cite

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Direct Color Observation of Light‐Driven Molecular Conformation‐Induced Stress

et al. 2021

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Although usually complex to handle, nanomechanical sensors are exceptional, label‐free tools for monitoring molecular conformational changes, which makes them of paramount importance in understanding biomolecular interactions. Herein, a simple and inexpensive mechanical imaging approach based on low‐stiffness cantilevers with structural coloration (mechanochromic cantilevers (MMC)) is demonstrated, able to monitor and quantify molecular conformational changes with similar sensitivity to the classical optical beam detection method of cantilever‐based sensors (≈4.6 × 10–3 N m–1). This high sensitivity is achieved by using a white light and an RGB camera working in the reflection configuration. The sensor performance is demonstrated by monitoring the UV‐light induced reversible conformational changes of azobenzene molecules coating. The trans‐cis isomerization of the azobenzene molecules induces a deflection of the cantilevers modifying their diffracted color, which returns to the initial state by cis‐trans relaxation. Interestingly, the mechanical imaging enables a simultaneous 2D mapping of the response thus enhancing the spatial resolution of the measurements. A tight correlation is found between the color output and the cantilever's deflection and curvature angle (sensitivities of 5 × 10–3 Hue µm–1 and 1.5 × 10–1 Hue (°)–1). These findings highlight the suitability of low‐stiffness MMC as an enabling technology for monitoring molecular changes with unprecedented simplicity, high‐throughput capability, and functionalities.

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Nanomechanical sensor for rapid and ultrasensitive detection of tumor markers in serum using nanobody

et al. 2021

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Early cancer diagnosis requires ultrasensitive detection of tumor markers in blood. To this end, we develop a novel microcantilever immunosensor using nanobodies (Nbs) as receptors. As the smallest antibody (Ab) entity comprising an intact antigen-binding site, Nbs achieve dense receptor layers and short distances between antigen-binding regions and sensor surfaces, which significantly elevate the generation and transmission of surface stress. Owing to the inherent thiol group at the C-terminus, Nbs are covalently immobilized on microcantilever surfaces in directed orientation via one-step reaction, which further enhances the stress generation. For microcantilever-based nanomechanical sensor, these advantages dramatically increase the sensor sensitivity. Thus, Nb-functionalized microcantilevers can detect picomolar concentrations of tumor markers with three orders of magnitude higher sensitivity, when compared with conventional Ab-functionalized microcantilevers. This proof-of-concept study demonstrates an ultrasensitive, label-free, rapid, and low-cost method for tumor marker detection. Moreover, interestingly, we find Nb inactivation on sensor interfaces when using macromolecule blocking reagents. The adsorption-induced inactivation is presumably caused by the change of interfacial properties, due to binding site occlusion upon complex coimmobilization formations. Our findings are generalized to any coimmobilization methodology for Nbs and, thus, for the construction of high-performance immuno-surfaces. Electronic Supplementary Material Supplementary material (experimental section, HER2 detection using anti-HER2-mAb-functionalized microcantilevers) is available in the online version of this article at 10.1007/s12274-021-3588-4.

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Microcantilever arrays functionalised with spiropyran photoactive moieties as systems to measure photo-induced surface stress changes

Cited by 17 publications

References 45 publications

Silicon Microcantilever Sensors to Detect the Reversible Conformational Change of a Molecular Switch, Spiropyan

Silicon Microcantilever Sensors to Detect the Reversible Conformational Change of a Molecular Switch, Spiropyan

Direct Color Observation of Light‐Driven Molecular Conformation‐Induced Stress

Nanomechanical sensor for rapid and ultrasensitive detection of tumor markers in serum using nanobody

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