Gamma-butyrolactone (GBL) and Gamma-hydroxybutyrate (GHB) having a unique carbon footprint as defined by the percent modern carbon (pmc) are described herein. The percent modern carbon can be controlled by varying the amounts of biobased, renewable starting materials and petroleum-based starting materials to prepare GBL or GHB having a defined pmc or by preparing mixtures of GBL or GHB prepared from biobased renewable starting materials and GBL or GHB prepared from petroleum-based starting materials.

Medical grade yarns, medical devices constructed of such yarns, and methods for making such yarns and devices are described. Polyester drawn fibers, and more particularly high strength and high tenacity micro polyester fibers for use in medical devices, and methods of preparing the same are provided.

A staple cartridge assembly comprising an implantable layer is disclosed. The implantable layer comprises a top portion, a bottom portion, and structural walls interwoven between the top portion and the bottom portion.

Absorbable composite medical devices such as surgical meshes and braided sutures, which display two or more absorption/biodegradation and breaking strength retention profiles and exhibit unique properties in different clinical settings, are made using combinations of at least two types of yarns having distinctly different physicochemical and biological properties and incorporate in the subject construct special designs to provide a range of unique properties as clinically useful implants.

Resorbable multifilament yarns and monofilament fibers including poly-4-hydroxybutyrate and copolymers thereof with high tenacity or high tensile strength have been developed. The yarns and fibers are produced by cold drawing the multifilament yarns and monofilament fibers before hot drawing the yarns and fibers under tension at temperatures above the melt temperature of the polymer or copolymer. These yarns and fibers have prolonged strength retention in vivo making them suitable for soft tissue repairs where high strength and strength retention is required. The multifilament yarns have tenacities higher than 8.1 grams per denier, and in vivo, retain at least 65% of their initial strength at 2 weeks. The monofilament fibers retain at least 50% of their initial strength at 4 weeks in vivo. The monofilament fibers have tensile strengths higher than 500 MPa. These yarns and fibers may be used to make various medical devices for various applications.

A system for forming twisted or aligned electrospun fibers has been developed. The collector for the electrospun fibers is capable of rotation. In some instances, fibers are formed between two collectors, at least one of which rotates to twist the fibers into a multifilament bundle with increased strength. In a second embodiment, a cylindrical collector rotates, and charged polymer jet uniformly coats the surface of the collector. When a drum collector rotates at a high speed, electrospun fibers align and form an array. Optionally, different active agents can be included in the electrospinning solutions to form fiber constructs with different strengths and controlled release profiles, providing a reproducible method to generate complexed structures based on electrospun fibers and controlled drug delivery profiles.

Resorbable multifilament yarns and monofilament fibers including poly-4-hydroxybutyrate and copolymers thereof with high tenacity or high tensile strength have been developed. The yarns and fibers are produced by cold drawing the multifilament yarns and monofilament fibers before hot drawing the yarns and fibers under tension at temperatures above the melt temperature of the polymer or copolymer. These yarns and fibers have prolonged strength retention in vivo making them suitable for soft tissue repairs where high strength and strength retention is required. The multifilament yarns have tenacities higher than 8.1 grams per denier, and in vivo, retain at least 65% of their initial strength at 2 weeks. The monofilament fibers retain at least 50% of their initial strength at 4 weeks in vivo. The monofilament fibers have tensile strengths higher than 500 MPa. These yarns and fibers may be used to make various medical devices for various applications, including mesh sutures.

Methods to produce structures containing ultrafine fibers with average diameters from 10 nm to 10 m and more preferably from 50 nm to 5 m, have been developed. These methods produce ultrafine fibers without substantial loss of the polymer's weight average molecular weight. The ultrafine electrospun fibers have an unexpectedly higher degree of molecular orientation, and higher melt temperature than fibers derived by dry spinning. In the preferred embodiment, the polymer comprises 4-hydroxybutyrate. The ultrafine fibers are preferably derived by electrospinning. A solution of the polymer is dissolved in a solvent, pumped through a spinneret, subjected to an electric field, and ultrafine fibers with a high degree of molecular orientation are collected. These structures of ultrafine fibers can be used for a variety of purposes including fabrication of medical devices.

Methods to produce structures containing ultrafine fibers with average diameters from 10 nm to 10 m and more preferably from 50 nm to 5 m, have been developed. These methods produce ultrafine fibers without substantial loss of the polymer's weight average molecular weight. The ultrafine electrospun fibers have an unexpectedly higher degree of molecular orientation, and higher melt temperature than fibers derived by dry spinning. In the preferred embodiment, the polymer comprises 4-hydroxybutyrate. The ultrafine fibers are preferably derived by electrospinning. A solution of the polymer is dissolved in a solvent, pumped through a spinneret, subjected to an electric field, and ultrafine fibers with a high degree of molecular orientation are collected. These structures of ultrafine fibers can be used for a variety of purposes including fabrication of medical devices.

Compositions of P4HB with high purity have been developed. The compositions are prepared by washing P4HB biomass prior to solvent extraction, and precipitating P4HB from solution. The same solvent is preferably used to wash the P4HB biomass, and as a non-solvent to precipitate the polymer from a P4HB solvent solution. The highly pure P4HB compositions are suitable for preparing implants. The implants may be used for the repair of soft and hard tissues.