The spectroscopic characterization of biomolecular structures requires nanometer spatial resolution and chemical specificity. We perform full spatio-spectral imaging of dried purple membrane patches purified from Halobacterium salinarum with infrared vibrational scattering-type scanning near-field optical microscopy (s-SNOM). Using near-field spectral phase contrast based on the Amide I resonance of the protein backbone, we identify the protein distribution with 20 nm spatial resolution and few-protein sensitivity. This demonstrates the general applicability of s-SNOM vibrational nanospectroscopy, with potential extension to a wide range of biomolecular systems.

Force drift is a significant, yet unresolved, problem in atomic force microscopy (AFM). We show that the primary source of force drift for a popular class of cantilevers is their gold coating, even though they are coated on both sides to minimize drift. Drift of the zero-force position of the cantilever was reduced from 900 nm for gold-coated cantilevers to 70 nm (N =10; rms) for uncoated cantilevers over the first 2 hours after wetting the tip; a majority of these uncoated cantilevers (60%) showed significantly less drift (12 nm, rms). Removing the gold also led to ~10-fold reduction in reflected light, yet short-term (0.1–10 s) force precision improved. Moreover, improved force precision did not require extended settling; most of the cantilevers tested (9 out of 15) achieved sub-pN force precision (0.54 ± 0.02 pN) over a broad bandwidth (0.01–10 Hz) just 30 min after loading. Finally, this precision was maintained while stretching DNA. Hence, removing gold enables both routine and timely access to sub-pN force precision in liquid over extended periods (100 s). We expect that many current and future applications of AFM can immediately benefit from these improvements in force stability and precision.

A hyperlens is a super-resolution optical imaging device based on unique hyperbolic dispersions making the subdiffraction-limited information on objects propagate to the far-field. Here, we propose a new device consisting of a 4-inch waferscale spherical hyperlens array that allows high-throughput and easy-to-handle real-time biomolecular imaging. With this proposed device, we report the first experimental demonstration of real-time sub-diffraction-limited biomolecular imaging using a hyperlens. Hippocampal neuron cells are imaged using a hyperlens at a resolution down to 151 nm, much smaller than the diffraction limit of conventional imaging systems in the visible wavelength. These wafer-scale hyperlens devices have great potential for simple, compact, and low-cost integration with conventional optics and therefore a large variety of imaging applications in biology, pathology, medical science and general nanoscience.

Dye-doped hemispherical resonators are self-assembled on a distributed Bragg reflector based on hydrophobic effect. The size of hemispheres can be well-controlled with diameters ranging from 5 to 150 μm. Upon optical pumping, whispering gallery mode laser emission with transverse magnetic polarization is observed from the hemispheres. Application of the microlasers as refractive index gas sensors has been demonstrated by detecting the spectrum shift of the lasing mode, and the sensitivity higher than 130 nm/RIU is achieved. Our approach provides an effective technique to obtain high quality microlasers and opens an opportunity to employ the cost effective microlasers as high sensitive sensors.