High-throughput fabrication of high aspect ratio Ag/Al nanopillars for optical detection of biomarkers.

Nanomaterial-based optical techniques for biomarker detection have garnered tremendous attention from the nanofabrication community due to their high precision and enhanced limit of detection (LoD) features. These nanomaterials are highly responsive to local refractive index (RI) fluctuations, and their RI unit sensitivity can be tuned by varying the chemical composition, geometry, and dimensions of the utilized nanostructures. To improve the sensitivity and LoD values of these nanomaterials, it is common to increase both dimensions and aspect ratios of the fabricated nanostructures. However, limited by the complexity, prolonged duration, and elevated costs of the available nanofabrication techniques, mass production of these nanostructures remains challenging. To address not only high accuracy, but also speed and production effectiveness in these nanostructures' fabrication, our work reports, for the first time, a fast, high-throughput, and cost-effective nanofabrication protocol for routine manufacturing of polymer-based nanostructures with high sensitivity and calculated LoD in the pM range by utilizing anodized aluminum oxide (AAO) membranes as templates. Specifically, our developed platform consists of arrays of nearly uniform polystyrene nanopillars with an average diameter of ∼185 nm and aspect ratio of ∼11. We demonstrate that these nanostructures can be produced at a high speed and a notably low price, and that they can be efficiently applied for biosensing purposes after being coated with aluminum-doped silver (Ag/Al) thin films. Our platform successfully detected very low concentrations of human C-reactive protein (hCRP) and SARS-CoV-2 spike protein biomarkers in human plasma samples with LoDs of 11 and 5 pM, respectively. These results open new opportunities for day-to-day fabrication of high aspect ratio arrays of nanopillars that can be used as a base for nanoplasmonic sensors with competitive LoD values. This, in turn, contributes to the development of point-of-care devices and further improvement of the existing nanofabrication techniques, thereby enriching the fields of pharmacology, clinical analysis, and diagnostics.

Polydimethylsiloxane/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS for the analysis of lavender essential oil.

A novel microwave-assisted (MA) headspace solid-phase extraction (HS-SPE) based on polydimethylsiloxane (PDMS)/ZIF-8@GO sponge was developed for the simultaneous extraction and determination of essential oil constituents in lavender. The PDMS/ZIF-8@GO sponge with a high surface area and excellent adsorption capacity was successfully applied in the HS-SPE process. Microwave-assisted coupled with PDMS/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS was proposed. Different experimental parameters were investigated. The optimal conditions were found to be as follows: 2:1 as the quality ratio of ZIF-8 to GO, ZIF-8@GO dosage of 30 mg, microwave power of 600 W, extraction time of 10 min and desorption solvent of n-hexane. This method was successfully applied to the analysis of 11 samples of lavender in different varieties. A total of 52 compounds were identified by the proposed method. A good linearity was observed from 14 to 800 ng with a correlation coefficient (R2) value of >0.99. Multivariate statistical analysis was used to establish the relationship between the varieties and the volatile components for further discriminant analysis. These results demonstrated that the MA-PDMS/ZIF-8@GO is an efficient, sensitive and small sample consumption method for the determination of the essential oil in dried plant materials.

Direct immersion thin film solid phase microextraction of polychlorinated n-alkanes in cod liver oil.

A thin film-solid phase microextraction (TF-SPME) method was developed to test for 5 individual polychlorinated n-alkanes (PCAs) from commercial cod liver oil samples. This was accomplished by preparing a novel aluminum supported, hydrophilic-lipophilic balance/polydimethylsiloxane (HLB/PDMS) TF-SPME device that enabled direct immersion extraction from fish oil. Matrix-matched calibration gave a linear range from 0.075 µg/g to 0.75 µg/g with method limits of quantitation (MLOQ) ranging from 0.07 µg/g to 0.217 µg/g in oil. Standard addition calibration was performed using other fish oils demonstrating comparable slope to the external calibration. As a proof of concept, four fish oil brands were tested for contaminants; 1,1,1,3-tetrachlorodecane, 1,2,9,10-tetrachlorodecane, 1,2,13,14-tetrachlorotetradecane, and 1,1,1,3,14,15-hexachloropentadecane were detected above the MLOQ but below the range provided by the Stockholm Convention. This method provides an effective approach for cleanup and preconcentration of PCAs from oily matrices using inexpensive, and reusable microextraction devices that limit environmental impact of the sample preparation protocol.

Polydimethylsiloxane/ionic liquid sponge used in headspace solid-phase extraction coupled with GC-MS for rapid analysis of essential oil in lavender.

A headspace (HS) solid-phase extraction (SPE) based on polydimethylsiloxane (PDMS)/ionic liquid (IL) sponge was developed for the extraction of lavender essential oil. The PDMS after loading of 1-butyl-3-methylimidazolium tetrachloroferrate ([BMIM]FeCl4 ) with a high surface area and excellent adsorption capacity was successfully applied in the SPE process. Microwave distillation (MD) coupled with HS-PDMS/[BMIM]FeCl4 extraction after GC-MS was proposed. Various experimental parameters were studied. The optimal conditions were as follows: optimal IL, [BMIM]FeCl4 ; volume ratio of IL to ethanol, 1:5; extraction solvent, n-hexane; microwave power, 600 W; and irradiation time, 12 min. The limits of detection and quantification of the analytic compounds were in the ranges 4.00-16.32 and 10.00-40.00 ng, respectively. The intra-day and inter-day precisions were in the ranges 0.37-1.94% and 1.20-2.45%, respectively. Under the optimized conditions, 13 samples of 3 lavender varieties were analyzed, and 40 compounds were identified. Lavender varieties were distinguished using principal component analysis. The results showed that MD-HS-PDMS/IL-GC-MS is a novel, simple, and sensitive method for the determination of essential oil in complex plant samples.

Direct Detection of Uranyl in Urine by Dissociation from Aptamer-Modified Nanosensor Arrays.

An ever-growing demand for uranium in various industries raises concern for human health of both occupationally exposed personnel and the general population. Toxicological effects related to uranium (natural, enriched, or depleted uranium) intake involve renal, pulmonary, neurological, skeletal, and hepatic damage. Absorbed uranium is filtered by the kidneys and excreted in the urine, thus making uranium detection in urine a primary indication for exposure and body burden assessment. Therefore, the detection of uranium contamination in bio-samples (urine, blood, saliva, etc.,) is of crucial importance in the field of occupational exposure and human health-related applications, as well as in nuclear forensics. However, the direct determination of uranium in bio-samples is challenging because of "ultra-low" concentrations of uranium, inherent matrix complexity, and sample diversity, which pose a great analytical challenge to existing detection methods. Here, we report on the direct, real-time, sensitive, and selective detection of uranyl ions in unprocessed and undiluted urine samples using a uranyl-binding aptamer-modified silicon nanowire-based field-effect transistor (SiNW-FET) biosensor, with a detection limit in the picomolar concentration range. The aptamer-modified SiNW-FET presented in this work enables the simple and sensitive detection of uranyl in urine samples. The experimental approach has a straight-forward implementation to other metals and toxic elements, given the availability of target-specific aptamers. Combining the high surface-to-volume ratio of SiNWs, the high affinity and selectivity of the uranyl-binding aptamer, and the distinctive sensing methodology gives rise to a practical platform, offering simple and straightforward sensing of uranyl levels in urine, suitable for field deployment and point-of-care applications.

Development and Characterization of A New Dimethicone Nanoemulsion and its Application for Electronic Gastroscopy Examination.

PURPOSE: Although the effective and safe medical defoamers, dimethicone (DM) and simethicone (SM) are widely used in electronic gastroscope examination (EGE), their preparations are presented in the form of suspensions or emulsions, these are untransparent or milk-like in appearance and can easily cause misdiagnosis as a result of an unclear field of vision if the doctor does not master the amount of defoamer or operates incorrectly. At the same time, it is also difficult to wash out the camera and pipeline, due to the large oil droplets of preparations. The purpose of this study was to develop a new clear and transparent oil in water (O/W) DM nanoemulsions (DMNs) and observe the effect of application in EGE. METHODS: The oil phase was chosen for its antifoaming activity and viscosity. The emulsifier and co-emulsifier were selected according to the solubility of the oil phase in them. The water titration method was used to make the pseudoternary phase diagrams of nanoemulsions and optimize the prescription composition. DM-in-water nanoemulsion was prepared by the low energy method and evaluated for appearance, antifoaming ability, droplet size, and stability. The effect of DMNs utilized in EGEs was also observed. RESULTS: The optimal formulation of DMNs contained CRH-40 as an emulsifier, PEG-400 as a co-emulsifier, DM as oil phase with the viscosity of 10 mPa.s, and their proportion was 4.5:4.5:1, respectively. DMNs obtained the average particle size of 67.98 nm with the polydispersity index (PDI) of 0.332, and 57.14% defoaming rate. The result of using an EGE showed that DMNs were superior in comparison to the emulsions with regard to the defoaming effect, visual clarity, and easy cleanup. CONCLUSION: DMNs were found to provide excellent visual clarity to its other preparations. The novel DMNs is a promising substitute for DM emulsions or suspensions in EGEs.

Optimization and validation of automated solid-phase microextraction arrow technique for determination of phosphorus flame retardants in water.

In the present work, a very sensitive and fully automated direct immersion PAL SPME Arrow procedure, coupled with GC-MS, has been developed and validated for determination of nine phosphorus flame retardants in different types of water samples (river, drinking and rainwater). PDMS/DVB was selected among three commercially available SPME Arrows (PDMS/DVB, DVB/PDMS/CWR and PDMS/CWR), since it resulted in the best sensitivity. The important experimental parameters were optimized via a central composite design response surface methodology and as result, extraction time of 65 min, extraction temperature of 80 °C and added salt concentration of 19% (w/v), were selected as the optimum values. The optimized method showed linear response over the calibration range (2 - 500 ng L-1), with R2-values higher than 0.9937. The precision (RSD%) measured by replicate analyses (n = 7) was estimated at 2 and 100 ng L-1 and was less than 29% and 21%, respectively. The LOQ of PAL SPME Arrow, calculated as S/N = 10, was between 0.2 and 1.2 ng L-1 (for triphenyl phosphate and tris-(1­chloro­2-propyl) phosphate, respectively) with extraction efficiencies between 5.9 and 31% (for tris-(1,3-dichloro-2-propyl) phosphate and tri-n­butyl phosphate, respectively). To assess the performance of the developed technique for real samples, two river water samples, tap water from two regions and a rainwater sample were analyzed. Most of the target analytes were observed in the river samples with concentrations of 1.0 - 250 ng L-1 and the obtained recoveries at 50 ng L-1 ranged between 60 and 107%. Considering the figures of merit of the optimized method, PAL SPME Arrow-GC-MS showed to be the most sensitive analytical approach for determination of phosphorus flame retardants in water, with satisfying precision and accuracy, compared with conventional SPME-NPD, LLE-GC-MS and SPE-LC-MS/MS.

High-throughput automated organoid culture via stem-cell aggregation in microcavity arrays.

Stem-cell-derived epithelial organoids are routinely used for the biological and biomedical modelling of tissues. However, the complexity, lack of standardization and quality control of stem cell culture in solid extracellular matrices hampers the routine use of the organoids at the industrial scale. Here, we report the fabrication of microengineered cell culture devices and scalable and automated methods for suspension culture and real-time analysis of thousands of individual gastrointestinal organoids trapped in microcavity arrays within a polymer-hydrogel substrate. The absence of a solid matrix substantially reduces organoid heterogeneity, which we show for mouse and human gastrointestinal organoids. We use the devices to screen for anticancer drug candidates with patient-derived colorectal cancer organoids, and apply high-content image-based phenotypic analyses to reveal insights into mechanisms of drug action. The scalable organoid-culture technology should facilitate the use of organoids in drug development and diagnostics.

Self-Sufficient and Highly Efficient Gold Sandwich Upconversion Nanocomposite Lasers for Stretchable and Bio-applications.

Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au1)-UCNP-gold (Au2)] capable of exhibiting lasing at ultralow thresholds under CW excitation are demonstrated. The metastable energy-level characteristics of lanthanides are advantageous for creating population inversion. In particular, localized surface plasmon resonance-based electromagnetic hotspots in the nanocomposites and the huge enhancement of scattering coefficient for the formation of coherent closed loops due to multiple scattering facilitate the process of stimulated emissions as confirmed by theoretical simulations. The nanocomposites are subjected to stretchable systems for enhancing the lasing action (threshold ∼ 0.06 kW cm-2) via a light-trapping effect. The applications in bioimaging of HeLa cells and antibacterial activity (photothermal therapy) are demonstrated using the newly designed Au1-UCNP-Au2 nanocomposites.

Enzyme induced molecularly imprinted polymer on SERS substrate for ultrasensitive detection of patulin.

We designed a new type of MIP-SERS substrate for specific and label-free detection of patulin (PAT), by combining molecular imprinting polymer (MIP) selectivity and SERS technology sensitivity. Initially, the solid substrate of PDMS/AAO was prepared using poly dimethylsiloxane (PDMS) concreted anodized aluminum oxide (AAO) template. Then moderate Au was sputtered on the surface of PDMS/AAO to obtain Au/PDMS/AAO SERS substrate. Based on the HRP enzyme initiated in situ polymerization on the Au/PDMS/AAO, the MIP-SERS substrate was successfully synthesized with selective polymer and high tense of SERS "hot spots". The new MIP-SERS substrate showed strong SERS enhancement effect and good selectivity for PAT. Besides, the results showed that the method owned a linear range from 5 × 10-10 to 10-6 M with the limit of detection (LOD) of 8.5 × 10-11 M (S/N = 3) for PAT. The proposed method also exhibited acceptable reproducibility (relative standard deviation, RSD = 4.7%)，good stability (Raman intensity is above 80% after two weeks) and recoveries from 96.43% to 112.83% with the average RSD of 6.3%. The substrate is easy to use without complex sample pretreatment, which makes it a potential candidate as a rapid and sensitive detection method in food samples.

A low-cost paper-based platform for fast and reliable screening of cellular interactions with materials.

A paper-based platform was developed and tested for studies on basic cell culture, material biocompatibility, and activity of pharmaceuticals in order to provide a reliable, robust and low-cost cell study platform. It is based upon a paper or paperboard support, with a nanostructured latex coating to provide an enhanced cell growth and sufficient barrier properties. Wetting is limited to regions of interest using a flexographically printed hydrophobic polydimethylsiloxane layer with circular non-print areas. The nanostructured coating can be substituted for another coating of interest, or the regions of interest functionalized with a material to be studied. The platform is fully up-scalable, being produced with roll-to-roll rod coating, flexographic and inkjet printing methods. Results show that the platform efficiency is comparable to multi-well plates in colorimetric assays in three separate studies: a cell culture study, a biocompatibility study, and a drug screening study. The color intensity is quantified by using a common office scanner or an imaging device and the data is analyzed by a custom computer software without the need for expensive screening or analysis equipment.

Highly durable crack sensor integrated with silicone rubber cantilever for measuring cardiac contractility.

To date, numerous biosensing platforms have been developed for assessing drug-induced cardiac toxicity by measuring the change in contractile force of cardiomyocytes. However, these low sensitivity, low-throughput, and time-consuming processes are severely limited in their real-time applications. Here, we propose a cantilever device integrated with a polydimethylsiloxane (PDMS)-encapsulated crack sensor to measure cardiac contractility. The crack sensor is chemically bonded to a PDMS thin layer that allows it to be operated very stably in culture media. The reliability of the proposed crack sensor has been improved dramatically compared to no encapsulation layer. The highly sensitive crack sensor continuously measures the cardiac contractility without changing its gauge factor for up to 26 days (>5 million heartbeats), while changes in contractile force induced by drugs are monitored using the crack sensor-integrated cantilever. Finally, experimental results are compared with those obtained via conventional optical methods to verify the feasibility of building a contraction-based drug-toxicity testing system.

Fabrication of unconventional inertial microfluidic channels using wax 3D printing.

Inertial microfluidics has emerged over the past decade as a powerful tool to accurately control cells and microparticles for diverse biological and medical applications. Many approaches have been proposed to date in order to increase the efficiency and accuracy of inertial microfluidic systems. However, the effects of channel cross-section and solution properties (Newtonian or non-Newtonian) have not been fully explored, primarily due to limitations in current microfabrication methods. In this study, we overcome many of these limitations using wax 3D printing technology and soft lithography through a novel workflow, which eliminates the need for the use of silicon lithography and polydimethylsiloxane (PDMS) bonding. We have shown that by adding dummy structures to reinforce the main channels, optimizing the gap between the dummy and main structures, and dissolving the support wax on a PDMS slab to minimize the additional handling steps, one can make various non-conventional microchannels. These substantially improve upon previous wax printed microfluidic devices where the working area falls into the realm of macrofluidics rather than microfluidics. Results revealed a surface roughness of 1.75 µm for the printed channels, which does not affect the performance of inertial microfluidic devices used in this study. Channels with complex cross-sections were fabricated and then analyzed to investigate the effects of viscoelasticity and superposition on the lateral migration of the particles. Finally, as a proof of concept, microcarriers were separated from human mesenchymal stem cells using an optimized channel with maximum cell-holding capacity, demonstrating the suitability of these microchannels in the bioprocessing industry.

A self-healable and antifouling hydrogel based on PDMS centered ABA tri-block copolymer polymersomes: a potential material for therapeutic contact lenses.

Herein we have prepared an antifouling and self-healable poly(dimethyl siloxane) (PDMS) based hydrogel which consists of a mixture of curcumin loaded zwitterionic PDMS polymersomes and amine functionalized PDMS polymersomes prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization and a Schiff-base reaction. The curcumin loaded polymersome consists of a PDMS and poly([dimethyl-[3-(2-methyl-acryloylamino)-propyl]-(3-sulfopropyl)ammonium)] (poly(sulfobetaine)) based tri-block copolymer (BCP) and it was characterized by dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses. To prepare the hydrogel, amine functionalized PDMS polymersomes were crosslinked with polyethylene glycol dialdehyde (PEG-DA) in pH 7.4 buffer solution via a Schiff-base reaction. This hydrogel was able to show sustained delivery of the entrapped curcumin drug for more than 72 h. The self-healing characteristic of the prepared hydrogel in the presence of saline water was elucidated by the "scratch and heal" method and subsequently analyzed through tensile study. Due to the presence of the poly(zwitterionic) moiety in the hydrogel system, it was observed that the hydrogel can efficiently reduce protein deposition, where Bovine Serum Albumin (BSA) was taken as a model protein. It was observed that the curcumin loaded hydrogel was detrimental towards both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. This type of smart soft hydrogel system can be a potential material for therapeutic applications for several eye diseases.

In vivo investigation of pesticide residues in garlic using solid phase microextraction-gas chromatography-mass spectrometry.

In this study, a novel multiwalled carbon nanotubes/polyaniline-polypyrrole@polydimethylsiloxane (MWCNTs/PANI-PPy@PDMS) fiber was prepared by a facile electrodeposition strategy followed by polymer surface modification, and used as the sorbent of in vivo solid phase microextraction (in vivo SPME). The custom-made fiber exhibits better enrichment capacity than three commercial SPME fibers. Ultra-high enrichment factor (438-2659), satisfactory thermal and mechanical stability, excellent matrix-compatibility and anti-biofouling ability render the fiber attractive as in vivo sampling probe. Combining in vivo SPME with gas chromatography-mass spectrometry (GC-MS), a convenient and sensitive method was successfully developed for the rapid determination of pesticides (hexachlorobenzene, chlorothalonil, fipronil, chlorfenapyr) in garlic. Under the optimal conditions, the proposed method displays relatively wide linear range (three or four orders of magnitude) with a coefficient of determination above 0.9944 both in the standard solution and spiked homogenized garlic samples, respectively. Low detection limits from 0.38 to 1.90 ng g-1 were obtained in homogenized garlic samples. Relative standard deviations (RSDs) less than 15.5% and recovery between 84.0% and 108.2% indicate satisfactory precision and accuracy of the method. In summary, a promising non-lethal method based on in vivo SPME-GC-MS is developed in this study, which provides a green, efficient, economic and rapid strategy for the determination of trace pesticide residues in edible plants.

Tissue-adhesive wirelessly powered optoelectronic device for metronomic photodynamic cancer therapy.

Metronomic (that is, low-dose and long-term) photodynamic therapy (mPDT) for treating internal lesions requires the stable fixation of optical devices to internal tissue surfaces to enable continuous, local light delivery. Surgical suturing-the standard choice for device fixation-can be unsuitable in the presence of surrounding major nerves and blood vessels, as well as for organs or tissues that are fragile, change their shape or actively move. Here, we show that an implantable and wirelessly powered mPDT device consisting of near-field-communication-based light-emitting-diode chips and bioadhesive and stretchable polydopamine-modified poly(dimethylsiloxane) nanosheets can be stably fixed onto the inner surface of animal tissue. When implanted subcutaneously in mice with intradermally transplanted tumours, the device led to significant antitumour effects by irradiating for 10 d at approximately 1,000-fold lower intensity than conventional PDT approaches. The mPDT device might facilitate treatment strategies for hard-to-detect microtumours and deeply located lesions that are hard to reach with standard phototherapy.

Bactericidal ZnO glass-filled thermoplastic polyurethane and polydimethyl siloxane composites to inhibit biofilm-associated infections.

This study investigates a novel approach to controlling biofilms of the most frequent pathogens implicated in the etiology of biomaterials-associated infections. New bactericidal filler based on a non-toxic glass, belonging to B2O3-SiO2-Al2O3-Na2O-ZnO system, was used to formulate composites of the most widely used polymers in biomedical applications [i.e. thermoplastic polyurethane (TPU) and polydimethyl siloxane (PDMS)], with varying percentage by weight of the bactericidal glass (5, 15, 25, 35, 50%). Glass-filled polymer composites show dramatically restricted bacterial colonisation and biofilm formation. They exhibit time- and dose-dependent killing, with maximal action at 5 days. The highest activity was found against S.epidermidis biofilm (99% of reduction), one of the most common cause of nosocomial infections. The tensile properties of the obtained glass-filled composites are comparable with the literature data concerning polymeric biomaterials for medical implants and devices. In addition, all the materials presented in this research, revealed an excellent biocompatibility. This was disclosed by cell viability values above 70%, none alteration on erythrocyte membrane or cell functionality in contact with materials (haemolytic index 0-2%), and absence of interferences in blood coagulation (intrinsic, extrinsic and final pathways).

Technical basis for using passive sampling as a biomimetic extraction procedure to assess bioavailability and predict toxicity of petroleum substances.

Solid-phase microextraction fibers coated with polydimethylsiloxane (PDMS) provide a convenient passive sampling format to characterize bioavailability of petroleum substances. Hydrocarbons absorb onto PDMS in proportion to both freely dissolved concentrations and partitioning properties of the individual constituents, which parallels the mechanistic basis used to predict aquatic toxicity in the PETROTOX model. When deployed in a non-depletive manner, combining SPME with thermal desorption and quantification using gas chromatography-flame ionization creates a biomimetic extraction (BE) procedure that has the potential to simplify aquatic hazard assessments of petroleum substances since the total moles of all hydrocarbons sorbed to the fiber can be related to toxic thresholds in target lipid of aquatic organisms. The objective of this work is to describe the technical basis for applying BE measurements to predict toxicity of petroleum substances. Critical BE-based PDMS concentrations corresponding to adverse effects were empirically derived from toxicity tests on different petroleum substances with multiple test species. The resulting species sensitivity distribution (SSD) of PDMS effect concentrations was then compared and found consistent with the previously reported target lipid-based SSD. Further, BE data collected on samples of aqueous media dosed with a wide range of petroleum substances were highly correlated to predicted toxic units derived using the PETROTOX model. These findings provide justification for applying BE in environmental hazard and risk evaluations of petroleum substances and related mixtures.

Genomic identification of microbial species adhering to maxillofacial prostheses and susceptibility to different hygiene protocols.

This study investigated the microbial colonization of maxillofacial prostheses and support tissues using the Checkerboard DNA-DNA hybridization method, and the efficacy of 0.12% chlorhexidine gluconate, 10% Ricinus communis solutions, or brushing, on colony forming unit (CFU) reduction in monospecies biofilms (Candida glabrata, Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa) formed on two silicones (MDX 4-4210 and Bio-Skin). Biofilm was harvested from 43 maxillofacial prosthesis wearers for detection of 38 species of microorganisms. The CFU counts of the six above mentioned species were recorded after using the hygiene protocols. All 38 investigated species were identified in prostheses and tissues, with a higher prevalence in the prostheses. 0.12% chlorhexidine gluconate immersion showed the greatest antimicrobial effectiveness, followed by mechanical brushing protocols. MDX 4-4210 silicone produced lower CFU counts than Bio-Skin.

Precision-porous templated scaffolds of varying pore size drive dendritic cell activation.

Scaffold based systems have shown significant potential in modulating immune responses in vivo. While there has been much attention on macrophage interactions with tissue engineered scaffolds for tissue regeneration, fewer studies have looked at the effects of scaffold design on the response of immune cells-that is, dendritic cells (DCs). Here, we present the effects of varying pore size of poly (2-hydroxyethyl methacrylate) (pHEMA) and poly(dimethylsiloxane) (PDMS, silicone) scaffolds on the maturation and in vivo enrichment of DCs. We employ a precision templating method to make 3-D porous polymer scaffolds with uniformly defined and adjustable architecture. Hydrophilic pHEMA and hydrophobic PDMS scaffolds were fabricated in three pore sizes (20, 40, 90 µm) to quantify scaffold pore size effects on DCs activation/maturation in vitro and in vivo. In vitro results showed that both pHEMA and PDMS scaffolds could promote maturation in the DC cell line, JAWSII, that resembled lipopolysaccharide (LPS)-activated/matured DCs (mDCs). Scaffolds with smaller pore sizes correlate with higher DC maturation, regardless of the polymer used. In vivo, when implanted subcutaneously in C57BL/6J mice, scaffolds with smaller pore sizes also demonstrated more DCs recruitment and more sustained activation. Without the use of DC chemo-attractants or chemical adjuvants, our results suggested that DC maturation and scaffold infiltration profile can be modulated by simply altering the pore size of the scaffolds.