Patent Application
20230083459
This disclosure relates to biologically compatible (bio-compatible) polymers, more particularly to polymers that can crosslink using a bio-compatible curing agent.
Existing spray-on bandages generally consist of low-viscosity solutions composed of dilute and/or low molecular weight polymers dissolved in a volatile solvent. After deposition of the solution, the solute rapidly evaporates leaving a coalesced film covering the wound. Due to the low viscosity and the low surface tension, the fluid forms thin films, making formation of thicker and more robust spray-on bandages improbable.
Ideally, spray-on bandages would be thicker and more robust, capable of incorporating drugs for slow release, similar to drug patches. This would allow a field-deployable, one-size-fits-all bandaging solution applicable in a fraction of the time needed for traditionally applied bandages.
Conventional atomizers and sprayer typically cannot spray viscous fluids. This limits the scope of potential spray-on bandages to dilute solutions of polymers, typically with a low-to-moderate molecular mass.
This results in a choice between sprayable compositions that cannot result from viscous fluids, resulting in a thin bandage, or using viscous fluids that eliminate the spray-on application.
According to aspects illustrated here, there is provided a system having a first fluid dispenser containing a biocompatible polymer, a second fluid dispenser containing a biocompatible curing agent selected to form a highly viscous mixture with the biocompatible polymer, a pair of diverging surfaces having a contact point, the first fluid dispenser and the second fluid dispenser positioned to dispense a first fluid and a second fluid at the contact point, and an actuator connected to the first fluid dispenser, the second fluid dispenser and the pair of diverging surfaces, the actuator configured to cause the first fluid dispenser and the second fluid dispenser to dispense the fluids at the contact point, and to cause the diverging surfaces to move through the contact point and then diverge, causing the mixture to form filaments until the filaments break up to form a spray.
According to aspects illustrate here, there is provided a method of forming a spray including dispensing a biocompatible polymer solution and a curing agent onto a pair of diverging surfaces to form a mixture, moving the two diverging surfaces counter to each other to cause the mixture to form filaments between the two diverging surfaces as the diverging surfaces move away from each other, moving the two diverging surfaces further counter to each other to cause the filaments burst into droplets, and directing the droplets onto a surface.
According to aspects illustrate here, there is provided a composition of matter comprising a biocompatible polymer and a biocompatible curing agent.
Generating sprays or mists from highly viscous materials presents several problems, mostly due to the ‘thickness,’ or resistance to flow of the material. The particles of the materials tend to have internal friction between layers of the fluid that flow at different rates, making them ‘sticky’ and hard to separate from other particles of the material. The terms “highly viscous” or “high viscosity” mean a viscosity of over 1 mPa-s (milliPascal-second).
The filament extension atomizer (FEA) technology developed at PARC emerged as a solution to this problem. FEA enables spraying of highly viscous formulations. Thin, low viscosity fluids, with or without a propellant, can easily be sprayed using pump or trigger sprayers. These methods do not work with higher viscosity fluids, but the FEA has had success in spraying these liquids.
Generally, FEA systems have diverging surfaces, such as a pair of counter-rotating rollers. The two surfaces come into contact and then move away from each other. Typically, a fluid is applied to one or both of the surfaces. The surfaces move towards each other and come into contact, or near contact, then diverge from each other. During contact, the fluid sticks to the surfaces, and then as them move away from each other, the fluid forms filaments that stretch between the surfaces until the strain causes the filament to burst into droplets and form the spray.
This system has one fluid dispenser containing a biocompatible polymer solution, and another fluid dispenser containing a biocompatible curing agent. As used here, the term “biocompatible” means any material not harmful to living tissue. The polymers used comprised biocompatible polymers, and the curing agent comprises a biocompatible curing agent. In some embodiments, the biocompatible polymer may comprise a biopolymer. As used here, “biopolymer” means a polymeric substance occurring in living organisms, such as polypeptides made up of amino acids, polysaccharides that include starches and sugars, and polynucleotides like DNA and RNA.
In the FEA component, the surfaces will be referred to as “diverging,” which means that the surfaces move away from each other at some point in their movement. The surfaces in this case will come into contact or near-contact and then move away from each other. As used here “near-contact” means that the surfaces come into close enough contact that the material sticks to both surface regardless of whether the materials were applied to one or both surfaces. The term “contact” will refer to both contact and near-contact for purposes of this discussion.
The materials may both be applied to one surface and then the other surface comes into contact with them at what is called the nip, the region where the two rollers are in contact or in the closest contact with each other. Each material may be applied separately, one to each roller, and then they combine at the nip to form a mixture. The material may also be applied into the nip directly, essentially applying both materials at the same time.
In
The biocompatible curing agent may comprise boric acid. Other biocompatible curing agents may be used, such as thiol-aldehyde combinations may result in weakly cross-linked structures. However, these typically require rarer aldehyde-containing sugars. These may also require some catalysis with a strong acid. Glutaraldehyde can also act as a cross-linker, but only cross-links at very high temperatures with an acid. The acid may result in a non-biocompatible result, so these may not be useful in applications involving interactions with human tissue.
The system 10 may also include an actuator 18 that activates the FEA component and the dispensers. The actuator could be something as simple as a button, pump or trigger that changes the pressure inside the system and causes the rollers to rotate. However, more than likely, some sort of controller will control the dispensers and the rollers. The controller 16 may comprise a microcontroller, a general purpose processor, a field-programmable gate array (FPGA), and application specific integrated circuit (ASIC), among many others. When the FEA component 20 generates the spray 22, it exits the housing to reach a surface.
The FEA component may take many different forms.
In this manner, one can spray more viscous materials that can hold other agents on a spray site, and the introduction of the curing agent allows the viscous material to cure and form a thick gel.
All features disclosed in the specification, including the claims, abstract, and drawings, and all the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the embodiments.
