A Controllable Molecular Sieve for Na⁺ and K⁺ Ions

The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na+ and K+ are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K+ or Na+ across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na+ or K+ confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water

Supplementary document for In vivo Evaluation of Endometrium Through Dual-modality Intrauterine Endoscopy - 5722527.pdf

Supplemental Document

Highly Sensitive Fluorescence and Photoacoustic Detection of Metastatic Breast Cancer in Mice Using Dual-Modal Nanoprobes

The biomedical imaging of metastatic breast cancer, especially in lymphatic and lung metastasis, is highly significant in cancer staging as it helps assess disease prognosis and treatment. Using an albumin-indocyanine green dual-modal nanoprobe developed in our laboratory, in vivo fluorescence imaging and photoacoustic imaging of metastatic breast cancer tumors were performed separately. Fluorescence imaging at the near-infrared window features high imaging sensitivity but is generally limited by a low imaging depth. Thus, tumors can only be observed in situ whereas tumor cells in the lymph nodes and lung cannot be imaged in a precise manner. In contrast, photoacoustic imaging often helps overcome the limitations of imaging depth with high acoustic spatial resolution, which could provide complementary information for imaging cancer metastases. Ex vivo fluorescence and photoacoustic imaging were also performed to verify the tumor metastatic route. This study may not only provide insights into the design of dual-modal nanoprobes for breast cancer diagnosis but may also demonstrate the superiority of combined fluorescence imaging and photoacoustic imaging for guiding, monitoring, and evaluating lymphatic and lung metastatic stages of breast cancer with a high imaging specificity as well as sensitivity

Media 1: Reflection-mode in vivo photoacoustic microscopy with subwavelength lateral resolution

Originally published in Biomedical Optics Express on 01 December 2014 (boe-5-12-4235

Illustration of the OR-PAT system.

<p>(a) Overall architecture of the system. (b) Schematic of the rotational mechanism of the catheter. (c) A photo of the catheter showing its flexibility. OPO, optical parametric oscillator; NDF, neutral density filter; ConL, condenser lens; BS: beam splitter; PD, photodiode; FC, fiber coupler; US, ultrasonics; PA, photoacoustics; SMF, single mode fiber; EC, electrical cable; 3D scanner, consisting of an optical-electric rotary joint (ROJ), a step motor, and a motorized pull-back stage.</p

Supplementary document for In-vivo assessment of rat rectal tumor using optical-resolution photoacoustic endoscopy - 6877424.pdf

supplementary materia

Spectroscopic OR-PAT of lipid.

<p>(a)–(d) Photoacoustic images at four different laser wavelengths of a phantom made by placing a small amount of butter into chicken breast tissue (see inset in (e)). The yellow box in (a) corresponds to the butter content in (e), while the white box in (d) indicates the area that photoacoustic signals are averaged for the photoacoustic spectra plot in (e). (e) Comparison between the acquired photoacoustic spectra of butter and previously reported optical absorption spectra of lipid <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092463#pone.0092463-Tsai1" target="_blank">[29]</a>.</p

OR-PAT of an iliac/common femoral artery stent.

<p>(a) Optical microscopic image of the imaged sent segment. (b) Representative 3D photoacoustic and (c) ultrasonic images. (d) Photoacoustic, (e) ultrasonic, and (f) fused B-scan images of a cross section of the stent. (g) Axial and (h) transverse photoacoustic (red) and ultrasonic (blue) signal profiles of a wire junction at 2 o′clock in (f). PA, photoacoustics; US, ultrasonics; Trans., transverse.</p

Additional file 1: of Indocyanine Green Loaded Reduced Graphene Oxide for In Vivo Photoacoustic/Fluorescence Dual-Modality Tumor Imaging

The supplementary characterization results of rNGO-PEG/ICG. (DOCX 2405 kb

Photoacoustic and ultrasonic imaging with OR-PAT of a stent deployed in a plastic tube.

<p>Three-dimensional cut-away (a) photoacoustic and (d) ultrasonic images. Representative (b) photoacoustic and (e) ultrasonic B-scans. Enlarged photoacoustic (c) and ultrasonic images corresponding to the dash boxes in (b) and (e).</p