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US-20260124304-A1 - Methods of Producing Cobalt Nanoparticles and Hollow Metal Nanospheres

US20260124304A1US 20260124304 A1US20260124304 A1US 20260124304A1US-20260124304-A1

Abstract

Provided are methods of producing cobalt-based nanoparticles (Co x B y NPs) of a pre-selected diameter. The methods include reducing Co 2+ ions with a sodium borohydride (NaBH 4 ) solution having a selected ratio of tetrahydroxyborate (B(OH) 4 − ) to tetrahydroborate (BH 4 − ) based on the pre-selected diameter, where the ratio of B(OH) 4 − to BH 4 − is positively correlated with the pre-selected diameter. Also provided are methods of using the Co x B y NPs to produce hollow metal nanospheres (HMNs). Methods of producing Co x B y NP core/metal shell structures are also provided, such methods including combining in an anaerobic galvanic exchange reaction a deaerated solution including Co x B y NP scaffolds and a deaerated solution including a metal. Also provided are methods of producing HMNs from the Co x B y NP core/metal shell structures. Compositions and kits that find use in practicing the methods of the present disclosure and using HMNs produced in accordance with the methods of the present disclosure, are also provided.

Inventors

  • Sarah Lindley
  • Jin Z. Zhang

Assignees

  • THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Dates

Publication Date
20260507
Application Date
20250905

Claims (20)

  1. 1 .- 55 . (canceled)
  2. 56 . A composition comprising a population of monodisperse hollow metal nanospheres (HMNs) having an average diameter with a relative standard deviation (RSD) of 4% or less.
  3. 57 . The composition of claim 56 , wherein the RSD is 3% or less.
  4. 58 . The composition of claim 56 , wherein the average diameter is from 20 nm to 80 nm.
  5. 59 . The composition of claim 56 , wherein the average diameter is from 30 nm to 70 nm.
  6. 60 . The composition of claim 56 , wherein the average diameter is from 40 nm to 60 nm.
  7. 61 . The composition of claim 56 , wherein the HMNs exhibit a surface plasmon resonance (SPR) absorption with a maximum peak position of from 565 nm to 850 nm.
  8. 62 . The composition of claim 56 , wherein the average diameter is from 20 nm to 80 nm, and wherein the HMNs exhibit an SPR absorption with a maximum peak position of from 565 nm to 850 nm.
  9. 63 . The composition of claim 56 , wherein the HMNs are hollow gold nanospheres (HGNs).
  10. 64 . The composition of claim 56 , wherein the HMNs comprise a targeting moiety attached to the surface thereof.
  11. 65 . The composition of claim 64 , wherein the targeting moiety is selected from the group consisting of: an antibody, a ligand, an aptamer, a nucleic acid, and a small molecule.
  12. 66 . The composition of claim 64 , wherein the targeting moiety binds to a molecule on the surface of a target cell.
  13. 67 . The composition of claim 66 , wherein the target cell is a cancer cell.
  14. 68 . The composition of claim 56 , wherein the composition is suitable for human administration.
  15. 69 . The composition of claim 68 , wherein the composition is formulated for parenteral administration.
  16. 70 . A method of killing target cells by photothermal therapy (PTT) in a subject in need thereof, the method comprising: administering the composition of claim 64 to the subject, wherein the targeting moiety binds to a molecule on the surface of the target cells; and irradiating the HMNs to kill the target cells in the subject.
  17. 71 . The method of claim 70 , wherein the subject has cancer, and wherein the target cells are cancer cells in the subject.
  18. 72 . The method of claim 70 , wherein the average diameter is from 20 nm to 80 nm.
  19. 73 . The method of claim 70 , wherein the HMNs exhibit an SPR absorption with a maximum peak position of from 565 nm to 850 nm.
  20. 74 . The method of claim 70 , wherein the targeting moiety is selected from the group consisting of: an antibody, a ligand, an aptamer, a nucleic acid, and a small molecule.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62/636,824, filed Feb. 28, 2018, and U.S. Provisional Patent Application No. 62/471,401, filed Mar. 15, 2017, which applications are incorporated herein by reference in their entireties. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with Government support under contract number NNX15AQ01A awarded by the National Aeronautics and Space Administration. The Government has certain rights in the invention. INTRODUCTION Plasmonic metal nanostructures exhibit beneficial optical properties owing to their surface plasmon resonance (SPR), the collective oscillation of conduction band electrons that manifests as strong absorption and/or scattering at the oscillation frequency.1,2 As oscillation frequency is structure dependent, the SPR may be tuned by changing the size or shape of the nanoparticle.3-9 This tunability positions plasmonic metal nanoparticles as highly attractive components in nanomedicine,6-12 optoelectronics,13-18 and solar energy conversion.19-23 In these applications, hollow metal nanostructures have distinct advantages over their solid metal counterparts, including lower mass per particle for reduced material costs, higher surface-area-to-volume ratio for increased density of loading or catalytic sites, and enhanced plasmonic performance in applications like SERS, drug delivery, and catalysis.24-28 Furthermore, the SPR of hollow structures are more tunable as the hollow core provides an additional parameter to modify the overall electronic structure. For one structure of note, the hollow gold nanosphere (HGN), the SPR may be tuned across the visible wavelengths and into the near-infrared by adjusting the ratio of outer diameter to shell thickness (the aspect ratio).29 Increasing the aspect ratio, effectively red-shifting the SPR, may be accomplished by either increasing the diameter or thinning the shell. Because of this twofold tunability, the diameter and SPR frequency can in principle be independently adjusted, allowing for the formation of targeted photoactivated structures of specific size and optical functionality. As such, HGNs could therefore become a powerful platform for a variety of nano-enabled applications. Since the introduction of HGNs in 2005, much work has been done to elucidate their structure-dependent optical properties,29-32 gain reproducibility of synthesis,33,34 and demonstrate their use in a variety of applications.35-38 However, their formation mechanism has not yet been controlled to the point of achieving independent selection of both size and SPR. To this end, the synthesis must be investigated and improved to enable a high degree of control over diameter and shell thickness. HGN diameters are determined by those of their cobalt-based nanoparticle scaffolds, sacrificial templates onto which shells of gold are formed through galvanic exchange.29,39 These scaffolds are commonly made through sodium borohydride nucleation of aqueous cobalt salt. Although this reaction is often studied, it is not yet well understood. Disagreement exists in the literature over the identity of the main product (e.g., various cobalt-boron alloys have been reported) and size control methods remain elusive. In 2006, Schwartzberg et al. reported that small adjustments in overall scaffold diameter may be made by changes to the volume of both the sodium borohydride reducing agent and sodium citrate capping ligand used in scaffold synthesis, but larger sizes proved difficult to achieve reproducibly.29 In 2009, a combination of alcohol solvents and triblock copolymer surfactant were used to synthesize Co nanoparticles from 3.2 to 171.4 nm, but the larger size regime was plagued by broad size dispersion and precipitation, and analysis of the mid-range size regime reveals large relative standard deviations.40 In 2011, silica-coated Co—B nanoparticles were synthesized from 50 to 250 nm in diameter with improved relative standard deviation (15-19%) by adjusting the ratio of surfactant to cobalt salt precursor, but silica coating was required for particle stability and small size regimes were not demonstrated.41 Recently, Pu et al. showed that reaction temperature may be used to slow nucleation and promote growth from 24 to 122 nm in diameter, but resultant particles were polydisperse and exact sizes difficult to control.42 Although progress has been made, size control methods for cobalt-based nanoparticle systems remain limited and fine adjustments over a large size range have not been realized experimentally. While the HGN diameter is determined by that of its scaffold, the SPR frequency and full width at half maximum (FWHM) are determined by shell thickness and uniformity, structural parameters that are governed by the galvanic exchange process. Previously, Schwartzberg et al. showed that shell thickness could be increased simply by providing more gold during gal