Chemistry of inorganic compounds – Phosphorus or compound thereof – Oxygen containing
Reexamination Certificate
1999-04-21
2001-12-04
Hendrickson, Stuart L. (Department: 1754)
Chemistry of inorganic compounds
Phosphorus or compound thereof
Oxygen containing
C423S311000, C424S602000
Reexamination Certificate
active
06325987
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods for the preparation of minerals, especially phosphorus containing minerals, to the minerals thus prepared and to methods for their use. In accordance with certain embodiments, minerals are provided which are novel in that they are, at once, substantially homogeneous and non-stoichiometric. They can be produced through novel, low temperature techniques which offer excellent control of composition and morphology.
BACKGROUND OF THE INVENTION
There has been a continuing need for improved methods for the preparation of mineral compositions, especially phosphorus-containing minerals. This long-felt need is reflected in part by the great amount of research found in the pertinent literature. While such interest and need stems from a number of industrial interests, the desire to provide materials which closely mimic mammalian bone for use in repair and replacement of such bone has been a major motivating force. Such minerals are principally calcium phosphate apatites as found in teeth and bones. For example, type-B carbonated hydroxyapatite [Ca
5
(PO
4
)
3−x
(CO
3
)
x
(OH)] is the principal mineral phase found in the body, with variations in protein and organic content determining the ultimate composition, crystal size, morphology, and structure of the body portions formed therefrom.
Calcium phosphate ceramics have been fabricated and implanted in mammals heretofore in many different forms including as shaped bodies, in cements and otherwise. Different stoichiometric compositions such as hydroxyapatite (HAp), tricalcium phosphate (TCP), and tetracalcium phosphate (TTCP), have all been employed to this end in an attempt to match the adaptability, biocompatibility, structure and strength of natural bone. Despite tremendous efforts directed to the preparation of improved calcium phosphate and precursor hydroxyapatite materials for such uses, significant shortcomings still remain.
Early ceramic biomaterials exhibited problems derived from chemical and processing shortcomings that limited stoichiometric control, crystal morphology, surface properties, and, ultimately, reactivity in the body. Intensive milling and comminution of natural minerals of varying composition was required, followed by powder blending and ceramic processing at high temperatures to synthesize new phases for use in vivo.
A number of patents have issued which relate to ceramic biomaterials. Among these are U.S. Pat. No. 4,880,610, B. R. Constantz , “In situ calcium phosphate minerals—method and composition;” U.S. Pat. No. 5,047,031, B. R. Constantz, “In situ calcium phosphate minerals method;” U.S. Pat. No. 5,129,905, B. R. Constantz, “Method for in situ prepared calcium phosphate minerals;” U.S. Pat. No. 4,149,893, H. Aoki, et al, “Orthopaedic and dental implant ceramic composition and process for preparing same;” U.S. Pat. No. 4,612,053, W. E. Brown, et al, “Combinations of sparingly soluble calcium phosphates in slurries and pastes as mineralizers and cements;” U.S. Pat. No. 4,673,355 E. T. Farris, et al, “Solid calcium phosphate materials;” U.S. Pat. No. 4,849,193, J. W. Palmer, et al., “Process of preparing hydroxyapatite;” U.S. Pat. No. 4,897,250, M. Sumita, “Process for producing calcium phosphate;” U.S. Pat. No. 5,322,675, Y. Hakamatsuka, “Method of preparing calcium phosphate;” U.S. Pat. No. 5,338,356, M. Hirano, et al “Calcium phosphate granular cement and method for producing same;” U.S. Pat. No. 5,427,754, F. Nagata, et al., “Method for production of platelike hydroxyapatite;” U.S. Pat. No. 5,496,399, I. C. Ison, et al., “Storage stable calcium phosphate cements;” U.S. Pat. No. 5,522,893, L. C. Chow. et al., “Calcium phosphate hydroxyapatite precursor and methods for making and using same;” U.S. Pat. No. 5,545,254, L. C. Chow, et al., “Calcium phosphate hydroxyapatite precursor and methods for making and using same;” U.S. Pat. No. 3,679,360, B. Rubin, et al., “Process for the preparation of brushite crystals;” U.S. Pat. No. 5,525,148, L. C. Chow, et al., “Self-setting calcium phosphate cements and methods for preparing and using them;” U.S. Pat. No. 5,034,352, J. Vit, et al., “Calcium phosphate materials;” and U.S. Pat. No. 5,409,982, A. Imura, et al “Tetracalcium phosphate-based materials and process for their preparation.”
While improvements have been made in ceramic processing technology leading to ceramic biomaterials with better control over starting materials and, ultimately, the final products, improved preparative methods are still greatly desired. Additionally, methods leading to calcium phosphate containing biomaterials which exhibit improved biological properties are also greatly desired despite the great efforts of others to achieve such improvements.
Accordingly, it is a principal object of the present invention to provide improved minerals, especially phosphorus-containing minerals.
A further object of the invention is to provide methods for forming such minerals with improved yields, lower processing temperatures, greater flexibility and control of product formation, and the ability to give rise to minerals having improved uniformity, biological activity, and other properties.
Another object is to improve the yield and control of synthetic mineral formation processes.
Yet another object is to give rise to cement compositions useful in the repair or replacement of bone in orthopaedic and dental procedures.
A further object is to provide minerals which are both substantially uniform and which are non-stoichiometric.
Further objects will become apparent from a review of the present specification.
SUMMARY OF THE INVENTION
The present invention is directed to create new methods for the preparation of minerals, especially phosphorus-containing minerals. The invention also gives rise to uniquely formed minerals, including minerals having improved compositional homogeneity and to minerals having modified crystal structures. New minerals are also provided by the invention, including “non-stoichiometric” minerals, which differ from commonly found minerals, crystal structures which are found in nature, and structures which have traditionally “allowed” ratios of constituent atoms in unit cells.
The new paradigm created by this invention requires a specification of terms used in this invention. The general method starts from raw materials, which are described herein as salts, aqueous solutions of salts, stable hydrosols or other stable dispersions, and/or inorganic acids. The phases produced by the methods of this invention [Redox Precipitation Reaction (RPR) and HYdrothermal PRocessing (HYPR)] are generally intermediate precursor minerals in the physical form of powders, particulates, slurries, and/or pastes. These precursor minerals can be easily converted to a myriad of mixed and pure mineral phases of known and, in some cases, as yet unidentified mineral stoichiometries, generally via a thermal treatment under modest firing conditions compared to known and practiced conventional art.
The methods of the invention are energy efficient, being performed at relatively low temperature, have high yields and are amenable to careful control of product purity, identity and quality. Employment as biological ceramics is a principal use for the materials of the invention, with improved properties being extant. Other uses of the minerals and processes of the invention are also within the spirit of the invention.
REFERENCES:
patent: 3679360 (1972-07-01), Rubin et al.
patent: 4149893 (1979-04-01), Aoki et al.
patent: 4612053 (1986-09-01), Brown et al.
patent: 4673355 (1987-06-01), Farris et al.
patent: 4711769 (1987-12-01), Inoue et al.
patent: 4849193 (1989-07-01), Palmer et al.
patent: 4880610 (1989-11-01), Constantz
patent: 4891164 (1990-01-01), Gaffney et al.
patent: 4897250 (1990-01-01), Sumita
patent: 5034352 (1991-07-01), Vit et al.
patent: 5047031 (1991-09-01), Constantz
patent: 5053212 (1991-10-01), Constantz et al.
patent: 5129905 (1992-07-01), Constantz
patent: 5302362 (1994-04-01), Bedard
patent: 5322675 (1994-06-01), Hak
Erbe Erik M.
Sapieszko Ronald S.
Hendrickson Stuart L.
Vita Licensing, Inc.
Woodcock & Washburn LLP
LandOfFree
Minerals and methods for their production and use does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Minerals and methods for their production and use, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Minerals and methods for their production and use will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2601989