@article {48269, title = {Self-organizing actin patterns shape membrane architecture but not cell mechanics.}, journal = {Nature Communications}, volume = {8}, year = {2017}, month = {2017 Feb 13}, pages = {14347}, abstract = {

Cell-free studies have demonstrated how collective action of actin-associated proteins can organize actin filaments into dynamic patterns, such as vortices, asters and stars. Using complementary microscopic techniques, we here show evidence of such self-organization of the actin cortex in living HeLa cells. During cell adhesion, an active multistage process naturally leads to pattern transitions from actin vortices over stars into asters. This process is primarily driven by Arp2/3 complex nucleation, but not by myosin motors, which is in contrast to what has been theoretically predicted and observed in vitro. Concomitant measurements of mechanics and plasma membrane fluidity demonstrate that changes in actin patterning alter membrane architecture but occur functionally independent of macroscopic cortex elasticity. Consequently, tuning the activity of the Arp2/3 complex to alter filament assembly may thus be a mechanism allowing cells to adjust their membrane architecture without affecting their macroscopic mechanical properties.

}, issn = {2041-1723}, doi = {10.1038/ncomms14347}, author = {Fritzsche, M and Li, D and Colin-York, H and Chang, V T and Moeendarbary, E and Felce, J H and Sezgin, E and Charras, G and Betzig, E and Eggeling, C} } @article {5383, title = {Probing tension and dynamics in actomyosin mediated cell shape change.}, journal = {Molecular Biology of the Cell}, volume = {22}, year = {2011}, month = {2011}, author = {Higgins, C. D. and Tulu, U. S. and Gao, L. and Betzig, E and Kiehart, D. P. and Goldstein, B.} } @article {2091, title = {Sparse and composite coherent lattices. (With commentary)}, journal = {Physical Review A}, volume = {71}, year = {2005}, month = {2005 Jun 20}, pages = {063406}, abstract = {

A method is described that yields a series of (D+1)-element wave-vector sets giving rise to (D=2 or 3)-dimensional coherent sparse lattices of any desired Bravais symmetry and primitive cell shape, but of increasing period relative to the excitation wavelength. By applying lattice symmetry operations to any of these sets, composite lattices of N\>D+1 waves are constructed, having increased spatial frequency content but unchanged crystal group symmetry and periodicity. Optical lattices of widely spaced excitation maxima of diffraction-limited confinement and controllable polarization can thereby be created, possibly useful for quan- tum optics, lithography, or multifocal microscopy.

Commentary: Develops a formalism to find a set of wavevectors that create a periodic optical lattice of any desired Bravais symmetry by the mutual interference of the corresponding plane waves. Discovers two new classes of optical lattices, sparse and composite, that together permit the creation of widely spaced, tightly confined excitation maxima in 3D potentially suitable for high speed volumetric live cell imaging. The implementation of this idea was derailed by our exclusive focus on PALM at the time, and many of its goals have since been reached with our Bessel beam plane illumination microscope. Nevertheless, sparse and composite optical lattices may prove useful in atomic physics or for the fabrication of 3D nanostructures.

}, author = {Betzig, E} } @article {2092, title = {Proposed method for molecular optical imaging. (With commentary)}, journal = {Optics Letters}, volume = {20}, year = {1995}, month = {1995 Feb 1}, pages = {237-9}, abstract = {

We can resolve multiple discrete features within a focal region of m spatial dimensions by first isolating each on the basis of n \>/= 1 unique optical characteristics and then measuring their relative spatial coordinates. The minimum acceptable separation between features depends on the point-spread function in the (m + n)d-dimensional space formed by the spatial coordinates and the optical parameters, whereas the absolute spatial resolution is determined by the accuracy to which the coordinates can be measured. Estimates of each suggest that near-field fluorescence excitation microscopy/spectroscopy with molecular sensitivity and spatial resolution is possible.

Commentary: Inspired by my earlier work (see below) in single molecule imaging and the isolation of multiple exciton recombination sites within a single probe volume, here I proposed the principle which would eventually lead to PALM. Indeed, all methods of localization microscopy, including PALM, fPALM, PALMIRA, STORM, dSTORM, PAINT, GSDIM, etc. are specific embodiments of the general principle of single molecule isolation and localization I introduced here.

}, issn = {0146-9592}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19859146}, author = {Betzig, E} } @article {922, title = {Near-field spectroscopy of the quantum constituents of a luminescent system.}, journal = {Science}, volume = {264}, year = {1994}, month = {1994 Jun 17}, pages = {1740-5}, abstract = {

Luminescent centers with sharp (\<0.07 millielectron volt), spectrally distinct emission lines were imaged in a GaAs/AIGaAs quantum well by means of low-temperature near-field scanning optical microscopy. Temperature, magnetic field, and linewidth measurements establish that these centers arise from excitons laterally localized at interface fluctuations. For sufficiently narrow wells, virtually all emission originates from such centers. Near-field microscopy/spectroscopy provides a means to access energies and homogeneous line widths for the individual eigenstates of these centers, and thus opens a rich area of physics involving quantum resolved systems.

}, issn = {0036-8075}, doi = {10.1126/science.264.5166.1740}, author = {Hess, H F and Betzig, E and Harris, T D and Pfeiffer, L N and West, K W} } @article {2084, title = {Near-field spectroscopy of the quantum constituents of a luminescent system. (With commentary)}, journal = {Science}, volume = {264}, year = {1994}, month = {1994 Jun 17}, pages = {1740-5}, abstract = {

Luminescent centers with sharp (\<0.07 millielectron volt), spectrally distinct emission lines were imaged in a GaAs/AIGaAs quantum well by means of low-temperature near-field scanning optical microscopy. Temperature, magnetic field, and linewidth measurements establish that these centers arise from excitons laterally localized at interface fluctuations. For sufficiently narrow wells, virtually all emission originates from such centers. Near-field microscopy/spectroscopy provides a means to access energies and homogeneous line widths for the individual eigenstates of these centers, and thus opens a rich area of physics involving quantum resolved systems.

Commentary: Harald Hess and I joined forces, combining my near-field optical technology with his cryogenic scanned probe microscope to produce the first paper on high resolution spectroscopy beyond the diffraction limit. We discovered that the broad luminescence spectrum traditionally observed from quantum well heterostructures reflects a resolution-limited ensemble average of emission from numerous discrete sites of exciton recombination occurring at atomic-scale corrugations in the confining interfaces. With the combination of high spatial resolution from near-field excitation and high spectral resolution from cryogenic operation, we were able to isolate these emission sites in a multidimensional space of xy position and wavelength, even though their density was too great to isolate them on the basis of spatial resolution alone. This insight was very influential in the genesis of the concept (see above) that would eventually lead to far-field superresolution by PALM.

}, issn = {0036-8075}, doi = {10.1126/science.264.5166.1740}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17839907}, author = {Hess, H F and Betzig, E and Harris, T D and Pfeiffer, L N and West, K W} } @article {2096, title = {Near-field fluorescence imaging of cytoskeletal actin. (With commentary)}, journal = {Bioimaging}, volume = {1}, year = {1993}, month = {1993 Sep}, pages = {129-35}, abstract = {

Near-field scanning optical microscopy (NSOM) has been used to generate high resolution flourescence images of cytoskeletal actin within fixed mouse fibroblast cells. Comparison with other microscopic methods indicates a transverse resolution well beyond that of confocal microscopy, and contrast far more revealing than in force microscopy. Effects unique to the near field are shown to be involved in the excitation of flourescence, yet the resulting images remain readily interpretable. As an initial demonstration of its utility, the technique is used to analyze the actin-based cytoskeletal structure between stress fibers and in cellular protrusions formed in the process of wound healing.

Commentary: The first superresolution fluorescence imaging of a biological system: the actin cytoskeleton in fixed, cultured fibroblast cells. This work strongly influenced me in two ways. First, calculations based on the signal-to-noise-ratio in images of single actin filaments in the paper suggested that single molecule imaging might be feasible. This was soon proven to be the case (see above). Second, the limitations of exogenous labeling for superresolution microscopy were revealed: samples which appeared correctly stained by conventional microscopy often exhibited sketchy, punctuate labeling of actin filaments as well as substantial non-specific background in the corresponding near field images. Indeed, it was the advent of GFP, with its promise of dense labeling and perfect specificity, that lured me back to superresolution microscopy when I first heard of it in 2003.

}, author = {Betzig, E and Chichester, R J and Lanni, F and Taylor, D L} } @article {2085, title = {Single molecules observed by near-field scanning optical microscopy. (With commentary)}, journal = {Science}, volume = {262}, year = {1993}, month = {1993 Nov 26}, pages = {1422-5}, abstract = {

Individual carbocyanine dye molecules in a sub-monolayer spread have been imaged with near-field scanning optical microscopy. Molecules can be repeatedly detected and spatially localized (to approximately lambda/50 where lambda is the wavelength of light) with a sensitivity of at least 0.005 molecules/(Hz)(1/2) and the orientation of each molecular dipole can be determined. This information is exploited to map the electric field distribution in the near-field aperture with molecular spatial resolution.

Commentary: A paper of many firsts: the first single molecule microscopy; the first extended observations of single molecules under ambient conditions; the first localization of single molecules to near-molecular precision (\ 15 nm), the first determination of the dipole axes of single fluorescent molecules; and the first near-molecular resolution optical microscopy, when a single fluorescent molecule was used to map the evanescent electric field components in the vicinity of a 100 nm diameter near-field aperture. Although eventually supplanted by simpler far-field methods, this paper ushered in the era of single molecule imaging and biophysics, and inspired the concept that would eventually lead to PALM. Even today, near-field single molecule detection lives on in the {\textquotedblleft}zero mode waveguide{\textquotedblright} sequencing approach promoted by Pacific Biosciences.

}, issn = {0036-8075}, doi = {10.1126/science.262.5138.1422}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17736823}, author = {Betzig, E and Chichester, R J} } @article {2098, title = {Combined shear force and near-field scanning optical microscopy (With commentary)}, journal = {Applied Physics Letters}, volume = {60}, year = {1992}, month = {1002 Mar 9}, abstract = {

A distance regulation method has been developed to enhance the reliability, versatility, and ease of use of near-field scanning optical microscopy (NSOM). The method relies on the detection of shear forces between the end of a near-field probe and the sample of interest. The system can be used solely for distance regulation in NSOM, for simultaneous shear force and near-field imaging, or for shear force microscopy alone. In the latter case, uncoated optical fiber probes are found to yield images with consistently high resolution.

Commentary: To exploit the evanescent field that is the source of high resolution in near-field microscopy, the probe must be exceptionally close to the sample: \ 10 nm away for 30-50 nm resolution. Here we introduced a distance regulation mechanism based on transverse shear forces between the end of a dithered near-field probe and the sample, which permitted even samples of modest topography to be imaged. Simple, reliable, noninvasive, and applicable to a wide range of samples from whole fixed cells to semiconductor devices, shear force microscopy was a key enabling technology for near-field optics, and soon widely implemented.

}, author = {Betzig, E and Finn, P L and Weiner, J S} } @article {2097, title = {Near-field magneto-optics and high density data storage. (With commentary)}, journal = {Applied Physics Letters.}, volume = {61}, year = {1992}, month = {1992}, abstract = {

Near-field scanning optical microscopy (NSOM) has been used to image and record domains in thin-film magneto-optic (MO) materials. In the imaging mode, resolution of 30-50 nm has been consistently obtained, whereas in the recording mode, domains down to -60 nm have been written reproducibly. Data densities of -45 Gbits/in.{\textquoteright} have been achieved, well in excess\ of current magnetic or MO technologies. A brief analysis of speed and other issues indicates that the technique may represent a viable alternative to density data storage needs.

Commentary: The first demonstration of optical recording and playback beyond the diffraction limit, using magneto-optic multilayer films and polarization contrast near-field microscopy. Bits as small as 60 nm were recorded {\textendash} beyond estimates at the time of the superparamagnetic limit to bit stability. Bit densities of 45 Gbits/in2 were also achieved, well in excess of optical or magnetic recording technologies of the era. In the years following this work, massive resources were spent on the commercialization of near-field data storage, largely for naught.

}, author = {Betzig, E and Trautman, J K and Wolfe, R and Gyorgy, E M and Finn, P L and Kryder, M H and Chang, C H} } @article {2093, title = {Near-field optics: microscopy, spectroscopy, and surface modification beyond the diffraction limit. (With commentary)}, journal = {Science}, volume = {257}, year = {1992}, month = {1992 Jul 10}, pages = {189-95}, abstract = {

The near-field optical interaction between a sharp probe and a sample of interest can be exploited to image, spectroscopically probe, or modify surfaces at a resolution (down to approximately 12 nm) inaccessible by traditional far-field techniques. Many of the attractive features of conventional optics are retained, including noninvasiveness, reliability, and low cost. In addition, most optical contrast mechanisms can be extended to the near-field regime, resulting in a technique of considerable versatility. This versatility is demonstrated by several examples, such as the imaging of nanometric-scale features in mammalian tissue sections and the creation of ultrasmall, magneto-optic domains having implications for highdensity data storage. Although the technique may find uses in many diverse fields, two of the most exciting possibilities are localized optical spectroscopy of semiconductors and the fluorescence imaging of living cells.

Commentary: An overview of our work in near-field optics at the time, after our invention of the adiabatically tapered fiber probe and shear force feedback (see below) led to the first practical near-field scanning optical microscope. In this work, superresolution imaging via absorption, reflectivity, fluorescence, spectroscopy, polarization, and refractive index contrast were all demonstrated. Unlike all far-field superresolution fluorescence methods that were to appear a decade later, near-field microscopy remains the only superresolution technique capable of taking advantage of the full panoply of optical contrast mechanisms.

}, issn = {0036-8075}, doi = {10.1126/science.257.5067.189}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17794749}, author = {Betzig, E and Trautman, J K} } @article {2563, title = {Polarization contrast in near-field scanning optical microscopy.}, journal = {Applied Optics}, volume = {31}, year = {1992}, month = {1992 Aug 1}, pages = {4563-8}, abstract = {

Recent advances in probe design have led to enhanced resolution (currently as significant as \  12 nm) in optical microscopes based on near-field imaging. We demonstrate that the polarization of emitted and detected light in such microscopes can be manipulated sensitively to generate contrast. We show that the contrast on certain patterns is consistent with a simple interpretation of the requisite boundary conditions, whereas in other cases a more complicated interaction between the probe and the sample is involved. Finally application of the technique to near-filed magneto-optic imaging is demonstrated.

}, issn = {0003-6935}, doi = {10.1364/AO.31.004563}, author = {Betzig, E and Trautman, J K and Weiner, J S and Harris, T D and Wolfe, R} } @article {2564, title = {Breaking the diffraction barrier: optical microscopy on a nanometric scale.}, journal = {Science}, volume = {251}, year = {1991}, month = {1991 Mar 22}, pages = {1468-70}, abstract = {

In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution.

}, issn = {0036-8075}, doi = {10.1126/science.251.5000.1468}, author = {Betzig, E and Trautman, J K and Harris, T D and Weiner, J S and Kostelak, R L} } @article {2095, title = {Breaking the diffraction barrier: optical microscopy on a nanometric scale. (With commentary)}, journal = {Science}, volume = {251}, year = {1991}, month = {1991 Mar 22}, pages = {1468-70}, abstract = {

In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution.

Commentary: Introduced the adiabatically tapered single mode fiber probe to near-field scanning optical microscopy which, together with shear force feedback, made the technique a practical reality. Although earlier claims of superresolution via near-field microscopy existed for nearly a decade, this paper was the first to convincingly break Abbe{\textquoteright}s limit with visible light, as demonstrated by reproducibly resolving known, complex nanoscale patterns having features separated by much less than the wavelength. Whereas our fiber probe and shear force technologies were soon widely adopted and key to many novel applications (see above), the earlier methods proved to be technological dead ends, never achieving the results of their original claims. This experience taught me the most valuable lesson of my career: while it{\textquoteright}s bad to bullshit others, it{\textquoteright}s even worse to bullshit yourself. It{\textquoteright}s a lesson sadly unheeded by many current practitioners of superresolution microscopy.

}, issn = {0036-8075}, doi = {10.1126/science.251.5000.1468}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17779440}, author = {Betzig, E and Trautman, J K and Harris, T D and Weiner, J S and Kostelak, R L} }