Proteases play a pivotal role in regulating important physiological processes from food digestion to blood clotting. They are also important biomarkers for many diseases such as cancers. The importance of proteases has led to extensive efforts in the screening of proteases and their inhibitors as potential drug molecules. For example, human immunodeficiency virus (HIV) patients have been treated with HIV-1 protease inhibitors to prolong the life expectancy of patients. Such a close relationship between diseases and proteases provides a strong motivation for developing sensitive, selective, and robust protease assays and sensors, which can be exploited to discover new proteases and inhibitors. In this aspect, protease assays based on levels of proteolytic activities are more relevant than protease affinity assays such as immunoassays. In this review, recent developments of protease activity assays based on different detection principles are discussed and compared. For homogenous assays, fluorescence-based techniques are the most popular due to their high sensitivity and quantitative results. However, homogeneous assays have limited multiplex sensing capabilities. In contrast, heterogeneous assays can be employed to detect multiple proteases simultaneously, given the microarray technology that is already available. Among them, electrochemical methods, surface spectroscopy techniques, and enzyme-linked peptide protease assays are commonly used. Finally, recent developments in liquid crystal (LC)-based protease assays and their applications for detecting proteases and their inhibitors are discussed.

We decoupled the influence of different spatial geometries of oligoglycerol-based head groups and contributed to the goal of rational fluorosurfactant design for droplet microfluidics-based water-in-oil emulsions and suited applications.

BackgroundTuberculosis (TB) is the ninth leading cause of death worldwide and the leading cause from a single infectious agent, based on the WHO Global Tuberculosis Report in 2017. TB causes massive health care burdens in many parts of the world, specifically in the resource constrained developing world. Most deaths from TB could be prevented with cost effective early diagnosis and appropriate treatment.PurposeConventional TB detection methods are either too slow as it takes a few weeks for diagnosis or they lack the specificity and accuracy. Thus the objective of this study was to develop a fast and efficient detection for TB using surface enhanced Raman scattering (SERS) technique.MethodsSERS spectra for different forms of mycolic acids (MAs) that are both synthetic origin and actual extracts from the mycobacteria species were obtained by label-free direct detection mode. Similarly, we collected SERS spectra for γ-irradiated whole bacteria (WB). Measurements were done using silver (Ag) coated silicon nanopillar (Ag SNP) as SERS substrate.ResultsWe report the SERS based detection of MA, which is a biomarker for mycobacteria species including Mycobacterium tuberculosis. For the first time, we also establish the SERS spectral characterization of the three major forms of MA – αMA, methoxy-MA, and keto-MA, in bacterial extracts and also in γ-irradiated WB. We validated our findings by mass spectrometry. SERS detection of these three forms of MA could be useful in differentiating pathogenic and nonpathogenic Mycobacterium spp.ConclusionsWe have demonstrated the direct detection of three major forms of MA – αMA, methoxy-MA, and keto-MA, in two different types of MA extracts from MTB bacteria, namely delipidated MA and undelipidated MA and finally in γ-irradiated WB. In the near future, this study could pave the way for a fast and efficient detection method for TB, which is of high clinical significance.

Natural organisms are made of different types of microcompartments, many of which are enclosed by cell membranes. For these organisms to display a proper function, the microcompartments must be selectively permeable. For example, cell membranes are typically permeable toward small, uncharged molecules such as water, selected nutrients, and cell signaling molecules, but impermeable toward many larger biomolecules. Here, it is reported for the first time dynamic compartments, namely surfactant‐stabilized double emulsions, that display selective and tunable permeability. Selective permeability is imparted to double emulsions by stabilizing them with catechol‐functionalized surfactants that transport molecules across the oil shell of double emulsions only if they electrostatically or hydrophobically attract encapsulants. These double emulsions are employed as semipermeable picoliter‐sized vessels to controllably perform complexation reactions inside picoliter‐sized aqueous cores. This thus far unmet level of control over the transport of reagents across oil phases opens up new possibilities to use double emulsion drops as dynamic and selectively permeable microcompartments to initiate and maintain chemical and biochemical reactions in picoliter‐sized cell‐mimetic compartments.

range of rheological properties of capsulecontaining solutions that can be accessed; the formulation of capsule-based solutions displaying a pronounced shear thinning or a yield stress would be key to use them as 3D printable inks. Capsules with much thinner, flexible shells whose structure and surface composition can be varied over a wide range can be fabricated from emulsion drops by solidifying reagents at their surface. This can be achieved, if appropriate reagents are dispersed in the drop and complementary ones in the continuous phase. Once these reagents meet at the drop surface, they solidify through polymerization [21][22][23] or coacervation reactions. [24][25][26][27] Capsules with thin shells can also be produced from a single type of reagent, namely from chemically reactive surfactants, that are cross-linked at the drop surface. [28][29][30][31][32] However, the number of reagents that can be employed to form thin polymeric capsules through these approaches is limited. Flexible capsules that display a narrow size distribution, low permeability toward encapsulants, allow controlled exchanges of reagents, and are mechanically sufficiently stable to withstand significant shear stresses such that they can be processed into macroscopic materials through additive manufacturing techniques remain to be established. These capsules would open up a new field of their use as principal building blocks of macroscopic granular materials with well-defined micrometer-sized structures and locally varying compositions that go far beyond their current use as individually dispersed delivery vehicles.Here, we introduce a new type of viscoelastic, mechanically stable capsules that are composed of bioinspired ionically crosslinked catechol-functionalized block-copolymer surfactants. These capsules present Fe 3+ complexed catechols at their surface such that they have a high affinity to each other. Therefore, they cannot only be used as individually dispersed mobile carrier vehicles that enable triggered release of reagents, but also as principal building blocks of macroscopic soft materials. We demonstrate for the first time that these capsules are mechanically sufficiently stable to serve as principal building blocks of inks that can be 3D printed into macroscopic granular materials with well-defined micrometer-length-scale structures.Emulsion drops are often stabilized with polymeric surfactants that are crucial during drop production and storage. However, once the drops are converted into capsules, surfactants are usually superfluous or even devastating because they irreproducibly change the surface wettability of the Microcapsules are often used as individually dispersed carriers of active ingredients to prolong their shelf life or to protect premature reactions with substances contained in the surrounding. This study goes beyond this application and employs microcapsules as principal building blocks of macroscopic 3D materials with well-defined granular structures. To achieve this goal and inspired by nature, capsules ...