2 research outputs found
Optically-Gated Self-Calibrating Nanosensors: Monitoring pH and Metabolic Activity of Living Cells
Quantitative
detection of biological and chemical species is critical to numerous
areas of medical and life sciences. In this context, information regarding
pH is of central importance in multiple areas, from chemical analysis,
through biomedical basic studies and medicine, to industry. Therefore,
a continuous interest exists in developing new, rapid, miniature,
biocompatible and highly sensitive pH sensors for minute fluid volumes.
Here, we present a new paradigm in the development of optoelectrical
sensing nanodevices with built-in self-calibrating capabilities. The
proposed electrical devices, modified with a photoactive switchable
molecular recognition layer, can be optically switched between two
chemically different states, each having different chemical binding
constants and as a consequence affecting the device surface potential
at different extents, thus allowing the ratiometric internal calibration
of the sensing event. At each point in time, the ratio of the electrical
signals measured in the ground and excited states, respectively, allows
for the absolute concentration measurement of the molecular species
under interest, without the need for electrical calibration of individual
devices. Furthermore, we applied these devices for the real-time monitoring
of cellular metabolic activity, extra- and intracellularly, as a potential
future tool for the performance of basic cell biology studies and
high-throughput personalized medicine-oriented research, involving
single cells and tissues. This new concept can be readily expanded
to the sensing of additional chemical and biological species by the
use of additional photoactive switchable receptors. Moreover, this
newly demonstrated coupling between surface-confined photoactive molecular
species and nanosensing devices could be utilized in the near future
in the development of devices of higher complexity for both the simultaneous
control and monitoring of chemical and biological processes with nanoscale
resolution control
Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations
Significant
research efforts have been dedicated to the integration
of biological species with electronic elements to yield smart bioelectronic
devices. The integration of DNA, proteins, and whole living cells
and tissues with electronic devices has been developed into numerous
intriguing applications. In particular, the quantitative detection
of biological species and monitoring of biological processes are both
critical to numerous areas of medical and life sciences. Nevertheless,
most current approaches merely focus on the “monitoring”
of chemical processes taking place on the sensing surfaces, and little
efforts have been invested in the conception of sensitive devices
that can simultaneously “control” and “monitor”
chemical and biological reactions by the application of on-surface
reversible stimuli. Here, we demonstrate the light-controlled fine
modulation of surface pH by the use of photoactive molecularly modified
nanomaterials. Through the use of nanowire-based FET devices, we showed
the capability of modulating the on-surface pH, by intensity-controlled
light stimulus. This allowed us simultaneously and locally to control
and monitor pH-sensitive biological reactions on the nanodevices surfaces,
such as the local activation and inhibition of proteolytic enzymatic
processes, as well as dissociation of antigen–antibody binding
interactions. The demonstrated capability of locally modulating the
on-surface effective pH, by a light stimuli, may be further applied
in the local control of on-surface DNA hybridization/dehybridization
processes, activation or inhibition of living cells processes, local
switching of cellular function, local photoactivation of neuronal
networks with single cell resolution and so forth