Nuclear singlet multimers (NUSIMERs) with long-lived singlet states

Area of Science:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Biophysical chemistry
• Materials science

Background:

• NMR is crucial for chemical analysis, structure determination, and medical diagnostics.
• Developing novel biological sensors can improve protein structure investigation and disease targeting.
• Nuclear spin singlet states offer unique properties for sensing applications.

Purpose of the Study:

• To explore nuclear spin singlet states in dendritic macromolecules as a platform for stimuli-responsive probes.
• To develop and characterize a novel Nuclear Singlet Multimer (NUSIMER).
• To assess the potential of NUSIMER for biosensing applications.

Main Methods:

• Synthesis of a generation 5 poly(amidoamine) dendrimer (PAMAM) based NUSIMER.
• Measurement of nuclear spin singlet state lifetimes (T_s) and longitudinal relaxation times (T₁).
• Evaluation of NUSIMER stability in different environments (buffer, gel) and response to stimuli.

Main Results:

• NUSIMER contains approximately 90 nuclear spin singlet states per molecule with extended lifetimes (up to 10 seconds).
• Singlet lifetimes showed minimal changes in phosphate buffer and high-viscosity gel, even with paramagnetic oxygen.
• A stimulus-induced release of a protective moiety increased singlet lifetime without altering longitudinal relaxation time.

Conclusions:

• NUSIMER demonstrates robust and tunable nuclear spin singlet state lifetimes.
• The observed changes in singlet lifetime upon stimulation indicate potential for stimuli-responsive biosensing.
• NUSIMER represents a promising platform for developing novel biosensors for various applications.