Bioinspired magnetic nanoparticles as multimodal photoacoustic, photothermal and photomechanical contrast agents

Abstract

Nanoparticles from magnetotactic bacteria have been used in conventional imaging, drug delivery, and magnetic manipulations. Here, we show that these natural nanoparticles and their bioinspired hybrids with near-infrared gold nanorods and folic acid can serve as molecular high-contrast photoacoustic probes for single-cell diagnostics and as photothermal agents for single-cell therapy using laser-induced vapor nanobubbles and magnetic field as significant signal and therapy amplifiers. These theranostics agents enable the detection and photomechanical killing of triple negative breast cancer cells that are resistant to conventional chemotherapy, with just one or a few low-energy laser pulses. In studies in vivo, we discovered that circulating tumor cells labeled with the nanohybrids generate transient ultrasharp photoacoustic resonances directly in the bloodstream as the basis for new super-resolution photoacoustic flow cytometry in vivo. These properties make natural and bioinspired magnetic nanoparticles promising biocompatible, multimodal, high-contrast, and clinically relevant cellular probes for many in vitro and in vivo biomedical applications.

Magnetic Particles: Their Applications from Sample Preparations to Biosensing Platforms

“…In this section, we summarized recent studies of biosensing devices that apply magnetic materials. They have advantageous functional capabilities, such as their magnetic property, low background noise, good dispersions, and highly biocompatible surfaces with regard to the immobilized recognizable bioreceptors [34][35][36][37]. With the continuing multidisciplinary development of magnetic-particle-based biosensing techniques, these efforts have found the way for modern biological devices for on-site or high-throughput purposes by replacing sophisticated monitoring biomedical devices.…”

“…Colorimetric biosensing techniques are to transform the detection of biological elements into measurable color changes. Additionally, they are inexpensive and only require simple detection equipment [36,37]. For various colorimetric devices for analysis, lateral flow tests (LFA) and paper devices are the main methods which are commonly associated with enzyme-linked immunosorbent assay (ELISA) to identify targets [38].…”

Bacteriophage-mediated identification of bacteria using photoacoustic flow cytometry

“…19 More recently, in vivo photoacoustics have been used with magnetotactic bacteria as well as the detection of infected phagocytic macrophage cells through a novel interaction and selfassembly. 20,21 In contrast, our method uses a bacterial tag, bacteriophage that binds irreversibly and specifically, and does not require a bacterial culture step or DNA amplification, such as many clinical diagnostics. Accuracy can be achieved by leveraging bacteriophage that binds to bacteria irreversibly and with specificity, 22 including to subspecies, often correlating with antibiotic sensitivity patterns.…”

Widefield illumination photoacoustic imaging of blood vessel phantom

“…Alongside conventional optical imaging modalities such as diffuse optical tomography and optical coherence tomography, PA imaging, also known as optoacoustic imaging, can overcome the limitations of shallow imaging depth or optical diffusion in highly turbid media, as well as provide a solution to the problem of low image contrast because of speckle artifacts, which is associated with the abovementioned solely optical imaging modalities . The latter advantage is a result of the detection of mechanical changes or ultrasonic waves as pressure signals, which are produced by thermoelastic expansion in the target objects upon the absorption of short‐pulsed laser beams, dependent on the laser wavelength . In this article, we present the demonstration of a simple and efficient PA imaging system, introducing widefield expanded‐laser‐beam illumination that fully covers the sample area of interest, in contrast to illumination based on point or focused sources .…”

“…3,4 The latter advantage is a result of the detection of mechanical changes or ultrasonic waves as pressure signals, which are produced by thermoelastic expansion in the target objects upon the absorption of short-pulsed laser beams, dependent on the laser wavelength. 5,6 In this article, we present the demonstration of a simple and efficient PA imaging system, introducing widefield expanded-laser-beam illumination that fully covers the sample area of interest, in contrast to illumination based on point or focused sources. 7,8 A filtered back-projection image-reconstruction algorithm was applied to the PA signals collected from a single transducer with a circular scanning receiver system.…”