Localized Instillation Enables In Vivo Screening of Targeting Peptides Using One-Bead One-Compound Technology.

The One-Bead One-Compound (OBOC) library screening is an efficient technique for identifying targeting peptides. However, due to the relatively large bead size, it is challenging for the OBOC method to be applied for in vivo screening. Herein, we report an in vivo Localized Instillation Beads library (LIB) screening method to discover targeting peptides with the OBOC technique. Inspired by localized instillation, we constructed a cavity inside of a transplanted tumor of a mouse. Then, the OBOC heptapeptide library was injected and incubated inside the tumor cavity. After an efficient elution process, the retained beads were gathered, from which three MDA-MB-231 tumor-targeting heptapeptides were discovered. It was verified that the best peptide had 1.9-fold higher tumor accumulation than the commonly used targeting peptide RGD in vivo. Finally, two targeting proteins were discovered as potential targets of our targeting peptide to the MDA-MB-231 tumor. The in vivo LIB screening method expands the scope of OBOC peptide screening applications to discover targeting peptides in vivo feasibly and reliably.

Bioinspired Screening of Anti-Adhesion Peptides against Blood Proteins for Intravenous Delivery of Nanomaterials.

Nanomaterials (NMs) inevitably adsorb proteins in blood and form "protein corona" upon intravenous administration as drug carriers, potentially changing the biological properties and intended functions. Inspired by anti-adhesion properties of natural proteins, herein, we employed the one-bead one-compound (OBOC) combinatorial peptide library method to screen anti-adhesion peptides (AAPs) against proteins. The library beads displaying random peptides were screened with three fluorescent-labeled plasma proteins. The nonfluorescence beads, presumed to have anti-adhesion property against the proteins, were isolated for sequence determination. These identified AAPs were coated on gold nanorods (GNRs), enabling significant extension of the blood circulating half-life of these GNRs in mice to 37.8 h, much longer than that (26.6 h) of PEG-coated GNRs. In addition, such AAP coating was found to alter the biodistribution profile of GNRs in mice. The bioinspired screening strategy and resulting peptides show great potential for enhancing the delivery efficiency and targeting ability of NMs.

Ultrathin surface coated water-soluble cobalt ferrite nanoparticles with high magnetic heating efficiency and rapid in vivo clearance.

To obtain magnetic nanoparticles with high magnetic heating efficiency and rapid in vivo clearance, this study utilized an improved linear response theory model to theoretically simulate the specific absorption rate (SAR) value versus the particle size of cobalt ferrite nanoparticles (CFNPs). An accurate SAR curve consistent with experimental results was obtained using cubes instead of spheres as the shape of CFNPs, given that cube was closer to the actual shape of prepared CFNPs. Under the guidance of simulation, we predicted and prepared water-soluble cubic CFNPs of 10-13 nm in size, with an ultrathin surface coating less than 1 nm in thickness. These CFNPs were experimentally verified to have high magnetic heating efficiency and rapid in vivo clearance rate. Our CFNPs of 11.8 nm in size had a high intrinsic loss power of 12.11 nHm2/kg. Most of the cells were killed within 30 min under magnetic heating with CFNPs. In an in vivo study, these CFNPs can heat a tumor area to 45 °C (ΔT > 9 °C) within 120 s under a weak alternating magnetic field (27 kA/m, 115 kHz). Notably, these CFNPs had significant tumor inhibition rate in vivo and can be cleared from the body by more than 64% within 2 weeks, demonstrating excellent rapid in vivo clearance. This result was close to the clearance level of the magnetic resonance imaging contrast agent Feridex. Therefore, our CFNPs had high magnetic heating efficiency and rapid in vivo clearance rate, indicating their great potential for future clinical applications.

Temperature field simulation and phantom validation of a Two-armed Spiral Antenna for microwave thermotherapy.

In this paper, an Archimedean planar spiral antenna for the application of thermotherapy was designed. This type of antenna was chosen for its compact structure, flexible application and wide heating area. The temperature field generated by the use of this Two-armed Spiral Antenna in a muscle-equivalent phantom was simulated and subsequently validated by experimentation. First, the specific absorption rate (SAR) of the field was calculated using the Finite Element Method (FEM) by Ansoft's High Frequency Structure Simulation (HFSS). Then, the temperature elevation in the phantom was simulated by an explicit finite difference approximation of the bioheat equation (BHE). The temperature distribution was then validated by a phantom heating experiment. The results showed that this antenna had a good heating ability and a wide heating area. A comparison between the calculation and the measurement showed a fair agreement in the temperature elevation. The validated model could be applied for the analysis of electromagnetic-temperature distribution in phantoms during the process of antenna design or thermotherapy experimentation.

Hybrid magnetic nanoparticle/nanogold clusters and their distance-dependent metal-enhanced fluorescence effect via DNA hybridization.

To improve the metal-enhanced fluorescence (MEF) effect of nanogolds (AuNPs) and accurately detect specific DNA sequences via DNA hybridization, novel hybrid magnetic nanoparticles/nanogold clusters (HMNCs) were designed based on finite-difference time-domain simulation results and prepared by using Fe3O4 and nanogolds. The nanogolds outside the HMNC were then conjugated with thiol-terminated DNA molecules, thus DNA modified-HMNCs (DNA-HMNCs) were obtained. The size distributions of these nanostructures were measured by a Malvern size analyzer, and their morphology was observed via transmission electron microscopy (TEM). The ultraviolet (UV)-visible (vis) absorption spectra of the samples were recorded with a UV-2600 spectrophotometer. Fluorescence spectra and the MEF effect were recorded using a spectrophotofluorometer, and lifetimes were determined using a time-correlated single photon counting apparatus. The prepared HMNCs were stable in aqueous solutions and had an average diameter of 87 ± 3.2 nm, with six to eight AuNPs around a single Fe3O4 nanoparticle. Fluorescein isothiocyanate (FITC) tagged DNA-HMNC conjugates exhibited a significant MEF effect and could accurately detect specific DNA sequences after DNA hybridization. This result indicates their various potential applications in sensors and biomedical fields.