The advantageous physiochemical properties of poly(dimethylsiloxane) (PDMS) have made it an extremely useful material for prototyping in various technological, scientific, and clinical areas. However, PDMS molding is a manual procedure and requires tedious assembly steps, especially for 3D designs, thereby limiting its access and usability. On the other hand, automated digital manufacturing processes such as stereolithography (SL) enable true 3D design and fabrication. Here the formulation, characterization, and SL application of a 3D-printable PDMS resin (3DP-PDMS) based on commercially available PDMS-methacrylate macromers, a high-efficiency photoinitiator and a high-absorbance photosensitizer, is reported. Using a desktop SL-printer, optically transparent submillimeter structures and microfluidic channels are demonstrated. An optimized blend of PDMS-methacrylate macromers is also used to SL-print structures with mechanical properties similar to conventional thermally cured PDMS (Sylgard-184). Furthermore, it is shown that SL-printed 3DP-PDMS substrates can be rendered suitable for mammalian cell culture. The 3DP-PDMS resin enables assembly-free, automated, digital manufacturing of PDMS, which should facilitate the prototyping of devices for microfluidics, organ-on-chip platforms, soft robotics, flexible electronics, and sensors, among others.

Stereolithography (SL) is emerging as an attractive alternative to soft lithography for fabricating microfluidic devices due to its low cost and high design efficiency. Low molecular weight poly(ethylene glycol)diacrylate (MW = 258) (PEG-DA-258) has been used for SL 3D-printing of biocompatible microdevices at submillimeter resolution. However, 3D-printing resins that simultaneously feature high transparency, high biocompatibility, and high resolution are still lacking. It is found that photosensitizer isopropyl thioxanthone can, in a concentration-dependent manner, increase the absorbance of the resin (containing PEG-DA-258 and photoinitator Irgacure-819) by over an order of magnitude. This increase in absorbance allows for SL printing of microdevices at sub pixel resolution with commercially available desktop printers and without compromising transparency or biocompatibility. The assembly-free, rapid (<15 h) 3D-printing of a variety of complex 3D microfluidic devices such as a 3D-fluid router, a passive chaotic micromixer, an active micro-mixer with pneumatic microvalves, and high-aspect ratio (37:1) microchannels of single pixel width is demonstrated. These manufacturing capabilities are unavailable in conventional microfluidic rapid prototyping techniques. The low absorption of small hydrophobic molecules and microfluidic labeling of cultured mammalian cells in 3D-printed PEG-DA-258 microdevices is demonstrated, indicating the potential of PEG-DA-based fabrication of cell-based assays, drug discovery, and organ-on-chip platforms.

BackgroundFor individuals who face challenges accessing clinic-based HIV pre-exposure prophylaxis (PrEP), differentiated service delivery models are needed to expand access and reach. During a pilot study testing a novel pharmacy-delivered oral PrEP model in Kenya, we used routine programmatic data to identify early implementation barriers and actions that providers and study staff took in response to the barriers.MethodsWe trained pharmacy providers at five private pharmacies in Kisumu and Kiambu Counties to initiate and continue clients at risk of HIV acquisition on PrEP for a fee of 300 KES per visit (∼$3 USD) using a prescribing checklist with remote clinician oversight. Research assistants stationed at the pharmacies completed weekly observation reports of pharmacy-delivered PrEP services using a structured template. We analyzed reports from the first 6 month of implementation using content analysis and identified multi-level early implementation barriers and actions taken to address these. We then organized the identified barriers and actions according to the Consolidated Framework for Implementation Research (CFIR).ResultsFrom November 2020 to May 2021, research assistants completed 74 observation reports (∼18/pharmacy). During this period, pharmacy providers screened 496 potential PrEP clients, identified 425 as eligible for pharmacy-delivered PrEP services, and initiated 230 (54%) on PrEP; 125 of 197 (63%) clients eligible for PrEP continuation refilled PrEP. We identified the following early implementation barriers to pharmacy-delivered PrEP services (by CFIR domain): high costs to clients (intervention characteristics), client discomfort discussing sexual behaviors and HIV testing with providers (outer setting), provider frustrations that PrEP delivery was time-consuming and disruptive to their workflow (inner setting), and provider hesitancy to deliver PrEP due to concerns about encouraging sexual promiscuity (characteristics of individuals). To help address these, pharmacy providers implemented a self-screening option for behavioral HIV risk assessment for prospective PrEP clients, allowed flexible appointment scheduling, and conducted pharmacy PrEP trainings for newly hired staff.ConclusionOur study provides insight into early barriers to implementing pharmacy-delivered PrEP services in Kenya and potential actions to mitigate these barriers. It also demonstrates how routine programmatic data can be used to understand the early implementation process.

Purpose of Review HIV self-testing (HIVST) has the potential to expand access to and uptake of HIV pre-exposure prophylaxis (PrEP) delivery. We conducted a systematic literature review to understand the evidence on HIVST use for PrEP delivery. Recent Findings After screening 1055 records, we included eight: three randomized trials and five values and preferences studies. None measured PrEP initiation. Most studies occurred in Sub-Saharan Africa (7/8) and included different populations. One trial found that HIVST use between quarterly clinic visits as part of an adherence package with biofeedback slightly increased adherence; the other two trials found that HIVST use between or in lieu of quarterly clinic visits had no significant or non-inferior effects on adherence. HIVST to support PrEP delivery was acceptable, feasible, and preferred. Summary HIVST use for PrEP continuation largely resulted in similar outcomes to standard-of-care delivery and was perceived acceptable and feasible. Further research is needed to optimize HIVST use within PrEP programming.