Droplet microfluidics: a tool for biology, chemistry and nanotechnology

The ability to perform laboratory operations on small scales using miniaturized devices provides numerous benefits, including reduced quantities of reagents and waste as well as increased portability and controllability of assays. These operations can involve reaction components in the solution phase and as a result, their miniaturization can be accomplished through microfluidic approaches. One such approach, droplet microfluidics, provides a high-throughput platform for a wide range of assays and approaches in chemistry, biology and nanotechnology. We highlight recent advances in the application of droplet microfluidics in chip-based technologies, such as single-cell analysis tools, small-scale cell cultures, in-droplet chemical synthesis, high-throughput drug screening, and nanodevice fabrication

Delayed Buckling and Guided Folding of Inhomogeneous Capsules

Colloidal capsules can sustain an external osmotic pressure; however, for a sufficiently large pressure, they will ultimately buckle. This process can be strongly influenced by structural inhomogeneities in the capsule shells. We explore how the time delay before the onset of buckling decreases as the shells are made more inhomogeneous; this behavior can be quantitatively understood by coupling shell theory with Darcy’s law. In addition, we show that the shell inhomogeneity can dramatically change the folding pathway taken by a capsule after it buckles.Engineering and Applied SciencesMolecular and Cellular BiologyPhysic

Primjena ekstrakta proteina sirutke u proizvodnji smrznutog mliječnog deserta

The aim of this work was to substantiate the use of whey protein extract (WPE), a by-product of dairy industry, combined with different berry purees in the formulation of a whipped frozen dairy dessert (WFDD). After freezing, the swelling ability of WPE decreased significantly while at higher temperatures of the dispersion medium, the degree of swelling increased. A mixture containing 55±2 % WPE and 45±2 % milk presented a homogeneous consistency while the further processing did not improve the structure of the mixture. Final formulations of WFDD containing different berry purees (i.e. 10 % black¬currant puree, 25 % cherry puree, or 30 % strawberry puree) were proposed for which the nutritional facts were calculated. Recommended shelf life of the developed desserts at -18 °C is suggested to be 20 days. Regulatory requirements and recommendations for the production of WFDD in an industrial scale were also developed. Recommended shelf life of the developed desserts at -18 °C is suggested to be 20 days. In conclusion, a WFDD was developed using WPE as a by-product of dairy industry.Svrha ovog rada bila je ispitati mogućnost primjene kombinacije pirea bobičastog voća i ekstrakta proteina sirutke (WPE), inače nusproizvoda mljekarske industrije, u proizvodnji smrznutog mliječnog deserta (WFDD). Nakon smrzavanja, sposobnost bubrenja WPE značajno je pala, međutim pri višim temperaturama medija za raspršivanje sposobnost bubrenja ponovno je rasla. U pogledu konzistencije najboljom se pokazala mješavina koja se sastojala od 55±2 % WPE i 45±2 % mlijeka te daljnja prera¬da nije rezultirala poboljšanjem teksture mješavine. Za konačne recepture WFDD s različitim udjelima pirea bobičastog voća (10 % pirea crnog ribizla, 25 % pirea višnje ili 30 % pirea jagode) napravljeni su izračuni prehrambene vrijednosti. Preporučeni rok trajanja za proizvedene deserte iznosio je 20 dana na temperaturi čuvanja -18 °C. Osim toga, uspostavljeni su zahtjevi sukladno zakonskim propisima kao i odgovarajuće preporuke za proizvodnju WFDD u industrijskom mjerilu. Zaključno, razvoj proizvodnje WFDD uključuje primjenu nusprizvoda mljekarske industrije - WPE

Primjena ekstrakta proteina sirutke u proizvodnji smrznutog mliječnog deserta

The aim of this work was to substantiate the use of whey protein extract (WPE), a by-product of dairy industry, combined with different berry purees in the formulation of a whipped frozen dairy dessert (WFDD). After freezing, the swelling ability of WPE decreased significantly while at higher temperatures of the dispersion medium, the degree of swelling increased. A mixture containing 55±2 % WPE and 45±2 % milk presented a homogeneous consistency while the further processing did not improve the structure of the mixture. Final formulations of WFDD containing different berry purees (i.e. 10 % black¬currant puree, 25 % cherry puree, or 30 % strawberry puree) were proposed for which the nutritional facts were calculated. Recommended shelf life of the developed desserts at -18 °C is suggested to be 20 days. Regulatory requirements and recommendations for the production of WFDD in an industrial scale were also developed. Recommended shelf life of the developed desserts at -18 °C is suggested to be 20 days. In conclusion, a WFDD was developed using WPE as a by-product of dairy industry.Svrha ovog rada bila je ispitati mogućnost primjene kombinacije pirea bobičastog voća i ekstrakta proteina sirutke (WPE), inače nusproizvoda mljekarske industrije, u proizvodnji smrznutog mliječnog deserta (WFDD). Nakon smrzavanja, sposobnost bubrenja WPE značajno je pala, međutim pri višim temperaturama medija za raspršivanje sposobnost bubrenja ponovno je rasla. U pogledu konzistencije najboljom se pokazala mješavina koja se sastojala od 55±2 % WPE i 45±2 % mlijeka te daljnja prera¬da nije rezultirala poboljšanjem teksture mješavine. Za konačne recepture WFDD s različitim udjelima pirea bobičastog voća (10 % pirea crnog ribizla, 25 % pirea višnje ili 30 % pirea jagode) napravljeni su izračuni prehrambene vrijednosti. Preporučeni rok trajanja za proizvedene deserte iznosio je 20 dana na temperaturi čuvanja -18 °C. Osim toga, uspostavljeni su zahtjevi sukladno zakonskim propisima kao i odgovarajuće preporuke za proizvodnju WFDD u industrijskom mjerilu. Zaključno, razvoj proizvodnje WFDD uključuje primjenu nusprizvoda mljekarske industrije - WPE

Microfluidic Fabrication of Colloidal Nanomaterials-Encapsulated Microcapsules for Biomolecular Sensing

Implantable sensors that detect biomarkers in vivo are critical for early disease diagnostics. Although many colloidal nanomaterials have been developed into optical sensors to detect biomolecules in vitro, their application in vivo as implantable sensors is hindered by potential migration or clearance from the implantation site. One potential solution is incorporating colloidal nanosensors in hydrogel scaffold prior to implantation. However, direct contact between the nanosensors and hydrogel matrix has the potential to disrupt sensor performance. Here, we develop a hollow-microcapsule-based sensing platform that protects colloidal nanosensors from direct contact with hydrogel matrix. Using microfluidics, colloidal nanosensors were encapsulated in polyethylene glycol microcapsules with liquid cores. The microcapsules selectively trap the nanosensors within the core while allowing free diffusion of smaller molecules such as glucose and heparin. Glucose-responsive quantum dots or gold nanorods or heparin-responsive gold nanorods were each encapsulated. Microcapsules loaded with these sensors showed responsive optical signals in the presence of target biomolecules (glucose or heparin). Furthermore, these microcapsules can be immobilized into biocompatible hydrogel as implantable devices for biomolecular sensing. This technique offers new opportunities to extend the utility of colloidal nanosensors from solution-based detection to implantable device-based detection. Keywords: biomolecular sensing; Microcapsules; microfluidic fabrication; nanosensorsJuvenile Diabetes Research Foundation International (Award 17-2013-507

Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification

Hypothesis Predicting formation mode of double emulsion drops in microfluidic emulsification is crucial for controlling the drop size and morphology. Experiments and modelling A three-phase Volume of Fluid-Continuum Surface Force (VOF–CSF) model was developed, validated with analytical solutions, and used to investigate drop formation in different regimes. Experimental investigations were done using a glue-free demountable glass capillary device with a true axisymmetric geometry, capable of readjusting the distance between the two inner capillaries during operation. Findings A non-dimensional parameter (ζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζ > 5.7, drops were formed in dripping mode; the widening jetting occurred at 5 < logζ < 5.7; while the narrowing jetting was observed at logζ < 5. The ζ criterion was correlated with the ratio of the break-up length to drop diameter. The transition from widening to narrowing jetting was achieved by increasing the outer fluid flow rate at the high capillary number of the inner fluid. The drop size was reduced by reducing the distance between the two inner capillaries and the minimum drop size was achieved when the distance between the capillaries was zero

Estimation of Nanoporosity of ZSM-5 Zeolites as Hierarchical Materials

The nanoporosity in zeolite ZSM-5 was analyzed as a function of SiO2/Al2O3 molar ratio (MR). The internal pore structure was studied by high-resolution adsorption. Surface areas, microporous volume, characteristic energy of sorption, and pore-size distributions were calculated from N2 sorption isotherms by the BET, Langmuir, t-method of de Boer, αS-plot of Sing, direct comparative plots of Lee, Newnham, Dubinin-Astakhov, differential adsorption curves, and nonlocal density functional theory methods. The results indicated that MR dependence in these zeolites caused structural defects through micropore opening and widening as well as the emergence of further slit-like mesopores