Manipulating Protein Conformations By Single-molecule Afm-fret Nanoscopy

Combining atomic force microscopy and fluorescence resonance energy transfer spectroscopy (AFM-FRET), we have developed a single-molecule AFM-FRET nanoscopy approach capable of effectively pinpointing and mechanically manipulating a targeted dye-labeled single protein in a large sampling area and simultaneously monitoring the conformational changes of the targeted protein by recording single-molecule FRET time trajectories. We have further demonstrated an application of using this nanoscopy on manipulation of single-molecule protein conformation and simultaneous single-molecule FRET measurement of a Cy3-Cy5-labeled kinase enzyme, HPPK (6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase). By analyzing time-resolved FRET trajectories and correlated AFM force pulling curves of the targeted single-molecule enzyme, we are able to observe the protein conformational changes of a specific coordination by AFM mechanic force pulling

Carrageenan-based hydrogels for the controlled delivery of PDGF-BB in bone tissue engineering applications

One of the major drawbacks found in most bone tissue engineering approaches developed so far consists in the lack of strategies to promote vascularisation. Some studies have addressed different issues that may enhance vascularisation in tissue engineered constructs, most of them involving the use of growth factors (GFs) that are involved in the restitution of the vascularity in a damaged zone. The use of sustained delivery systems might also play an important role in the re-establishment of angiogenesis. In this study, !-carrageenan, a naturally occurring polymer, was used to develop hydrogel beads with the ability to incorporate GFs with the purpose of establishing an effective angiogenesis mechanism. Some processing parameters were studied and their influence on the final bead properties was evaluated. Platelet derived growth factor (PDGF-BB) was selected as the angiogenic factor to incorporate in the developed beads, and the results demonstrate the achievement of an efficient encapsulation and controlled release profile matching those usually required for the development of a fully functional vascular network. In general, the obtained results demonstrate the potential of these systems for bone tissue engineering applications.This work was supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283), the European STREP HIPPOCRATES (NMP3-CT-2003-505758), and by the Portuguese Foundation for Science and Technology (FCT) through the project PTDC/FIS/68517/2006 and through the V. Espirito Santo's Ph.D. grant (SFRH/BD/39486/2007)

A comparative study of the vibro-impact capsule systems with one-sided and two-sided constraints

This is the final version of the article. Available from Springer Verlag via the DOI in this record.This paper studies the dynamics of the vibro-impact capsule systems with one-sided and two-sided soft constraints under variations of various system and control parameters, including mass ratio, stiffness ratio, gap of contact, and amplitude and frequency of external excitation. The aim of this study is to optimise the progression speed and energy consumption of the capsule, and minimize the required cabin length for prototype design used for engineering pipeline inspection. Our studies focus on three systems: the capsule with a right constraint, the capsule with a right and a weak left constraints, and the capsule with a right and a strong left constraints. Bifurcation analyses show that the behaviour of the capsule with one-sided constraint is mainly periodic, and the dynamic responses of the other two capsules with two-sided constraints become complex when the stiffness of the left constraint increases. Based on our extensive comparisons, the following optimisation strategies are recommended. When the capsule speed is paramount, one can employ the two-sided capsule with a weak left constraint under large amplitude of excitation. When energy consumption is taken into account, the one-sided capsule is preferable. When a miniaturized prototype is needed, the two-sided capsule with a strong left constraint is the best choice.Dr. Yang Liu would like to acknowledge the financial support from EPSRC for his First Grant (Grant No. EP/P023983/1). Dr. Yao Yan was supported by the National Natural Science Foundation of China (Grant No. 11572224 and 11502048) and the Fundamental Research Funds for the Central Universities (Grant No. ZYGX2015KYQD033)

Multi-objective optimization of a self-propelled capsule for small bowel endoscopy considering the influence of intestinal environment

This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordData availability: The datasets generated and analysed during the current study are available from the corresponding author on reasonable request.This work studies the control optimization of a self-propelled capsule moving in the small intestinal environment for endoscopic diagnosis. For this purpose, we combine an existing capsule model with the intestinal peristalsis and its internal environment in order to gain a better understanding of dynamics of the self-propelled capsule. For the optimization study, a number of different realistic targets are considered, including the capsule’s average progression speed, the impact force acting on the small intestine and the capsule’s energy consumption. In addition, the uncertainty of the small intestine environment is taking into account by varying its internal radius. In this setting, we develop a multi-objective optimization strategy based on NSGA-II, Monte Carlo, and Six-Sigma algorithms considering both the control and structural model parameters, such as excitation frequency and impact stiffness. The effectiveness of the proposed optimization strategy is demonstrated via extensive numerical simulations with the consideration of a wide range of realistic scenarios