Subdermal Antibiotic Wound Closure

Our recent foray into the old subdermal armor thread has sparked an interesting discussion on the viability of a subdermal implant containing a foaming, antibiotic compound, released when a serious injury is sustained. In the interest of keeping the 2 concepts clear cut and clean, I've started a separate thread on the topic. Here's a rough summary of the features, possibilities, and problems discussed thus far:

- Contained in a subdermal implant
- Antibiotic properties
- Trigger
- Hardening (pros and cons)
- Integration into the current medical infrastructure(Ease of removal by emergency personnel)
- Prevention of premature release
- Coagulating properties
- Integration into the body's current healing processes
- Removal

Here are a few topics that need to be discussed:
- Container
- Composition
- Cost
- Optimizations and other effects
- Feasibility of use for implants
- Anything else that comes to mind


  •  Per "-Anything else that comes to mind", @TheGreyKnight:
    Is the implant "smart", able to detect a serious injury? That sounds complicated.
    If the implant can be activated manually, after a serious injury, that sounds less complicated. Maybe a subcutaneous sterile saline solution? First step to healing a wound is cleaning.
  • ^ See the other thread where this was discussed already.

    It would have to have a coating that would only break on exposure to air and trauma, or potentially high levels of clotting agents indicative of a wound. When it breaks it would release a fluid that would quickly clean the area, expel debris and then partially solidify to temporarily seal the wound.
  • Since the foam issue is still up in the air... I found something that might work, at least as the foundation of the stuff. It's hydroxypropyl methylcellulose. It's soluble in water, non-toxic, forms a colloid (so no need to mix), and it reacts to heat to become a gel at a critical temperature. Any thought on whether or not this is viable? If we make it foam, in addition to a surfactant, we could used hydrogen peroxide, which would debride the wound as well. But, that might break down the antibiotic.
  • I still like the semi hard foam. Something that would set to the constancy of silicone. That way it'll expand, fill the wound and close it better than a gel that'll just seep. As to antibiotic screw it just use an antisepctic. mix in somthing like iodine (just an example, this is not ideal) and we need to keep the capsules small enough to go in with a 10 gauge ish needle. any bigger and it would look really odd and be rather irritating. The smaller the better though.
  • I think a good point was made about washing. While this multi step procedure would be more of a pain, it would be ideal.

    Also, a buddy of mine published this a while ago. It's basically a liquid at room temp and a gel at body temp. Spray on wound coating, very biofriendly.
    From what I understand, the state change due to temp has to do with the tails on some of the monomers/crosslinkers. You could probably take this idea, make it oxygen responsive, and get something that basically gets activated when exposed to air (like, when you are wounded...)

  • The only issue I can see is that it would gel prematurely since it's always sitting inside you. So we'd need something that goes the other way. It's liquid at body temp and solidifies when exposed to air since it cools down a bit.
  • The problem with that, however, is the fact that, because of inflammation, the wound site is going to stay warmer than normal. Oxygen-reactivity is a good idea. But... What if get injured during a shipwreck, or something. if the wound stays submerged, it'll be hard to get it to harden.

  • Ya i thought of that after I posted.  If you get hurt in a shipwreck you're sort of fucked anyway if we're being honest. And at that point the wound isn't your problem, the drowning is. Lets focus on terrestrial wounding
  • Yeah, you gotta keep your design specifications specific or the next thing you're like WHAT IF I WAS IN SPAAAACE? and off we go on another tangent.
    There are very few things that all the things in all the situations.

    So yeah, the opposite of the temp for sure. I was just using it as a reference for how these things toggle.
  • So, in terms of using hydrogen peroxide as a foaming agent/antiseptic, is this a good or bad idea? I know that it increases scarring and lengthens healing time, but the oxygen gas production makes it attractive.Can any of the antiseptics used for prepping for implantation be used on wounds (preferably without causing any more pain)? From the reading I did, Quats seem relatively ideal, though pairing them with another antiseptic to combat bacteria unaffected by them seems like a wise idea, that wouldn't be too complicated.

    And Speaking of pain, I mentioned this in the other thread, before we moved, but is adding a local anesthetic to the mix a good idea? It wouldn't have to be much (we're not trying to do a nerve block here. Just taking the edge off.). Perhaps a dilute solution of Lidocaine w/ Epi? 

    In addition to cleaning, numbing, and the other properties mentioned, I recall one thing that hasn't been discussed yet from the initial brainstorm. Clotting agents. Before I even go looking for them, can anyone with better medical training verify that using them would be a good idea, and if so, what kinds of side-effects can be expected? Now, you're probably thinking, "If we use Lido w/ Epi, wouldn't a clotting factor be overkill, because of the vasoconstricting effects of the epinephrine?" Perhaps. I don't know enough to say for sure, though. 

    I'm still looking around for compounds that will provide us with the desired physical characteristics (flexy, soft, liquid -> foam, thermal-oxygen reactivity).

  • edited February 2015
    As always, I'm gonna just kick the tires here. Not cause I don't think the idea isn't cool, but because I'm trying to get some other thoughts into the mix.

    The thing I always think when discussing projects like this is "how would this fail terribly?" If you can cover most of those concepts and avoid them, basically what's left over is something that will actually work. Maybe not the most perfect magical ideal, but something functional.

    So. Clotting agents. Let's consider them working. Are we going to cause a stroke situation? Like, clots are not always your friend. What if they don't work. Like it happens when you don't want it to. Cause I'm sure everyone has had something activate not when they want it to. Ok, now you have..  not so much wound mitigation as a not friendly blockage.

    However, if it wasn't internalized, I would use clotting agents over vasocontrictors, just because I think that clotting stops leaking while vcs reduce bloodflow, hindering healing and movement of natural agents in the body doing immediate mitigation of damage.

    I am not a big fan of antiseptics in general. Much over usage in my opinion, but that is up for debate.

    Hydrogen peroxide should not be in the body.

    The main issue to be addressed here is the internalization. The oxygen rxn hydrogel is actually pretty simple. It's the "wanna put it in the meat bits" action that is the issue. Like, How do you make it stay in place and release? Is it under all teh skin or in primary locations?  These are things that should be addressed first.

  • Ya not a fan of the clotting agent myselt so much as an absorbent sponge, which is what i've said time and time again. if it solidifyes and expands but actives at the wrong time it's a bit annoying and uncomfortable but a quick removal and you're fine. As to antiseptic I'm thinking more along the lines of silver nano particles rather than something a bacteria can get used to. So basically something that your body can easily pass if it ends up in your blood stream, is inert enough that it won't kill and can be pissed out, but also keep the wound clean. I addressed size since my thoughts are that you'd inject hundreds  of these beeds subdermally around areas where protections is needed. Arteries, major organs and places where knife wounds are more likely to hit. Keep the beeds small so they aren't able to be felt through the skin so you can have lots of them. Maybe lots of small single bead injections to get them in the right spot, or some sort of gel suspension that'll help keep them spread apart and can be absorbed into the body after injection maybe including a growth factor to speed setting. Or they could be long really skinny tubes? although that i feel would be far more prone to accidental failure. 
  • Keeping it in place probably be done using parylene-C (Not sure in what way it'd be used, just that it bonds to tissue, which is handy). Perhaps applying an intermittent coating to the outside of the implant, where enough oxygen-reactive material is exposed that the implant will trigger on exposure, but enough parylene is present that the implant won't migrate.

    If we went with jaaz's multi-bead idea for subdermal deployment, there are a number of worst case scenarios I can think of. Let's say we implant just below the dermis. Premature implant rupture could occur, due to repeated mechanical strain, defects in the implant shell, or blunt force if we fail to take such occurrences into account (Possible situations this could occur, other than getting beat up by the mafia: Falling down a flight of stairs, car wreck, an overzealous masseuse, parkour, excessive stretching). Using spheres negates some of the issues encountered with mechanical stress, though that doesn't go away entirely. If we include some form of biodegradability into the agent contained in the implant, similar to dissolving stitches, we wouldn't have to go digging to extract the errant activation. Could the oxygen in the body cause the agent to activate without exposure to air?

    With regards to implant location and distributing, I feel that strategic placement of the beads in areas prone to sustaining injuries of the nature we wish to treat would be optimal. If we're using spheres that fit inside a 10 gauge piercing needle, as jaaz suggested, whole body deployment would be, at the very least, extremely painful. That said, protecting major arteries and organs, along with accident prone bits (arms, hands, feet) would be the most feasible option. Are we going to follow standard implant procedures, and avoid implanting near joints?

    @glims You mentioned oxygen rxn hydrogel. I recall that you mentioned zwitterionic hydrogel-coated silk in a thread awhile back dealing with implant coatings. Do you have any papers or journal articles on the topic ( Didn't see any linked elsewhere in the forum, or in the community research library)? As someone who's worked with hydrogels, do you think they'd be suitable as a stand-alone filler? Or would they, like other gels, just ooze out of the wound? Also

    Silver nanoparticles would be good for antimicrobial properties, but I'm wondering what optimal "dosage" is at a wound site. I found a publication which probably details something in this regard, but it's behind a lovely paywall.( A few issues to consider with using silver nanoparticles: Argyria(Deposition of silver in tissues. As far as I can tell, this is just a cosmetic issue), and Allergic Reactions (which negate the possibility of people who are allergic to silver using our implants.)

  • 10 gauge is as big as i'd go. Ideally these would be way tinier but the smaller they are the harder they are to produce. Anything larger is easier to break due to blunt force trauma and would be way worse if one went off by accident. Also the point is you make these things fairly tough. they only weaken when exposed to air and reduced temeprature. If you make them so sensitive that bloody stretching sets them off then there's no point. The point is more that on contact with air, they weaken, dissolve a bit and the goo comes out. Or they get cut open by the attacker. Either way they don't just rupture.
  • Aye. In hindsight, everyone was probably aware of those potential points of failure, so that was unnecessary. That said, as of now, do you have anything in mind for use in the implant shell?
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