PDMS embedded microneedles as a controlled release system for the eye
Bibliographic record
Abstract
PURPOSE: To demonstrate intraocular drug delivery using a novel device fabricated by embedding hollow glass microneedles within a soft and flexible poly (dimethylsiloxane) (PDMS) substrate for ease of device insertion into the eye. METHODS: Hollow glass microneedles (5 µm ID tips), fabricated using standard glass drawing techniques, were assembled into a photolithographically micropatterned PDMS substrate. The microneedles were fluidically coupled to a drug reservoir through a 300 µm microchannel to test for in vitro release of 6-aminoquinolone (144 Da) and Rose Bengal (1044 Da). Intravitreal delivery in ex vivo bovine eyes was also studied. RESULTS: The microneedles penetrated UV-crosslinked collagen and excised bovine sclera without breaking or delaminating from the PDMS matrix. A total of 45 ng of 6-aminoquinolone and 16 µg of Rose Bengal was released into buffered saline over a 20-min infusion at a delivery rate of 50 µL/min. Microinjection of Rose Bengal for 8 h into ex vivo bovine vitreous resulted in a total mass accumulation of 0.0202 mg into both phases of the vitreous humor and to the uveal face of the sclera without clogging of the internal needle microchannel. CONCLUSIONS: PDMS-embedded microneedles offer an integrated method of drug targeting to the intraocular tissues using a less invasive and less painful approach when compared with macroscale hypodermic needles. The release rates from the microneedles were controllable on demand using a syringe pump and were independent of the properties of the drugs tested. The device demonstrated a new hybrid approach of coupling rigid microneedles strong enough to penetrate the tough, fibrous sclera with a soft and pliable PDMS substrate that could conform to the contours of the eye.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".