Integration of Biofunctional Molecules into 3D-Printed Polymeric Micro-/Nanostructures

Three-dimensional printing at the micro-/nanoscale represents a new challenge in research and development to achieve direct printing down to nanometre-sized objects. Here, FluidFM, a combination of microfluidics with atomic force microscopy, offers attractive options to fabricate hierarchical polymer structures at different scales. However, little is known about the effect of the substrate on the printed structures and the integration of (bio)functional groups into the polymer inks. In this study, we printed micro-/nanostructures on surfaces with different wetting properties, and integrated molecules with different functional groups (rhodamine as a fluorescent label and biotin as a binding tag for proteins) into the base polymer ink. The substrate wetting properties strongly affected the printing results, in that the lateral feature sizes increased with increasing substrate hydrophilicity. Overall, ink modification only caused minor changes in the stiffness of the printed structures. This shows the generality of the approach, as significant changes in the mechanical properties on chemical functionalization could be confounders in bioapplications. The retained functionality of the obtained structures after UV curing was demonstrated by selective binding of streptavidin to the printed structures. The ability to incorporate binding tags to achieve specific interactions between relevant proteins and the fabricated micro-/nanostructures, without compromising the mechanical properties, paves a way for numerous bio and sensing applications. Additional flexibility is obtained by tuning the substrate properties for feature size control, and the option to obtain functionalized printed structures without post-processing procedures will contribute to the development of 3D printing for biological applications, using FluidFM and similar dispensing techniques

Protein spot arrays on graphene oxide coatings for efficient single-cell capture

Biomedical applications such as cell screening or cell–cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes such as pattern stability and easy processing. Here, we present a simple yet effective approach to single-cell arraying based on a graphene oxide (GO) surface carrying protein (fibronectin) microarrays to define cell adhesion points. These capture NIH-3T3 cells, resulting in cell arrays, which are benchmarked against analogous arrays on silanized glass samples. We reveal significant improvement in cell-capture performance by the GO coating with regards to overall cell adhesion and single-cell feature occupancy. This overall improvement of cell-arraying combined with retained transparency of substrate for microscopy and good biocompatibility makes this graphene-based approach attractive for single-cell experiments

C-11/C-9 Helices in Crystals of alpha beta Hybrid Peptides and Switching Structures between Helix Types by Variation in the alpha-Residue

Close-packed helices with mixed hydrogen bond directionality are unprecedented in the structural chemistry of alpha-polypeptides. While NMR studies in solution state provide strong evidence for the occurrence of mixed helices in (beta beta)(n) and (alpha beta)(n) sequences, limited information is currently available in crystals. The peptide structures presented show the occurrence of C-11/C-9 helices in (alpha beta)(n) peptides. Transitions between C-11 and C-11/C-9 helices are observed upon varying the alpha-amino acid residue

Studies in microwave mediated solvent-free synthesis of 5-aryl-2,3- diphenylpyrroles from 4-aryl-1,2-diphenyl-2- butene-1,4-diones

1470-14744-Aryl-1,2-diphenyl-2-butene-1,4-diones and ammonium formate when irradiated with microwaves furnish 5-aryl-2,3-diphenylpyrroles in good yield under solvent-free conditions

C₁₁/C₉ Helices in Crystals of αβ Hybrid Peptides and Switching Structures between Helix Types by Variation in the α‑Residue

Close-packed helices with mixed hydrogen bond directionality are unprecedented in the structural chemistry of α-polypeptides. While NMR studies in solution state provide strong evidence for the occurrence of mixed helices in (ββ)_<i>n</i> and (αβ)_<i>n</i> sequences, limited information is currently available in crystals. The peptide structures presented show the occurrence of C₁₁/C₉ helices in (αβ)_<i>n</i> peptides. Transitions between C₁₁ and C₁₁/C₉ helices are observed upon varying the α-amino acid residue

Quality assurance studies in eight State tuberculosis laboratories in India

SETTING: Tuberculosis Research Centre, Chennai, India. OBJECTIVE: To undertake quality assurance studies in sputum smear microscopy at eight State-level laboratories in India using a panel of stained smears. DESIGN: Coded panels of stained smears (100 slides in rounds I–IV and 50 slides in Round V), comprising different grades of positivity, were sent to each centre at 6- monthly intervals. The results obtained were analysed for consistency of positive and negative results and overall agreement, as well as discordance. RESULTS: Consistency of positives ranged from 38% to 100%, indicating under-reading at some sites. The negative consistency was better, however, with only five of the total of 95 readers in all rounds yielding a consistency of less than 100%. Considering overall agreement, seven of the eight centres showed an agreement of over 90%. Four of the eight centres gave no false-positive result. For the remaining centres the false positivity rate varied from 2% to 7%. A wide variation was also observed in the proportion of false-negatives (3%–52%). CONCLUSIONS: This study helped in the evaluation of the performance of individual laboratories and in identifying the drawbacks of this system of proficiency testing

Physicochemical Properties Predict Retention of Antibiotics in Water-in-Oil Droplets

Water-in-oil droplet microfluidics promises capacity for high-throughput single-cell antimicrobial susceptibility assays and investigation of drug resistance mechanisms. Every droplet must serve as an isolated environment with a controlled antibiotic concentration in such assays. While technologies for generation, incubation, screening, and sorting droplets mature, predictable retention of active molecules inside droplets remains a major outstanding challenge. Here, we analyzed 36 descriptors of the antibiotic molecules against experimental results on the cross-talk of antibiotics in droplets. We show that partition coefficient and fractional polar surface area are the key physicochemical properties that predict antibiotic retention. We verified the prediction by monitoring growth inhibition by antibiotic-loaded neighboring droplets. Our experiments also demonstrate that transfer of antibiotics between droplets is concentration- and distance-dependent. Our findings immediately apply to designing droplet antibiotic assays and give deeper insight into the retention of small molecules in water-in-oil emulsions