Cantilever signature of tip detachment during contact resonance AFM.

Contact resonance atomic force microscopy, piezoresponse force microscopy, and electrochemical strain microscopy are atomic force microscopy modes in which the cantilever is held in contact with the sample at a constant average force while monitoring the cantilever motion under the influence of a small, superimposed vibrational signal. Though these modes depend on permanent contact, there is a lack of detailed analysis on how the cantilever motion evolves when this essential condition is violated. This is not an uncommon occurrence since higher operating amplitudes tend to yield better signal-to-noise ratio, so users may inadvertently reduce their experimental accuracy by inducing tip-sample detachment in an effort to improve their measurements. We shed light on this issue by deliberately pushing both our experimental equipment and numerical simulations to the point of tip-sample detachment to explore cantilever dynamics during a useful and observable threshold feature in the measured response. Numerical simulations of the analytical model allow for extended insight into cantilever dynamics such as full-length deflection and slope behavior, which can be challenging or unobtainable in a standard equipment configuration. With such tools, we are able to determine the cantilever motion during detachment and connect the qualitative and quantitative behavior to experimental features.

Nanosac, a Noncationic and Soft Polyphenol Nanocapsule, Enables Systemic Delivery of siRNA to Solid Tumors.

For systemic delivery of small interfering RNA (siRNA) to solid tumors, the carrier must circulate avoiding premature degradation, extravasate and penetrate tumors, enter target cells, traffic to the intracellular destination, and release siRNA for gene silencing. However, existing siRNA carriers, which typically exhibit positive charges, fall short of these requirements by a large margin; thus, systemic delivery of siRNA to tumors remains a significant challenge. To overcome the limitations of existing approaches, we have developed a carrier of siRNA, called "Nanosac", a noncationic soft polyphenol nanocapsule. A siRNA-loaded Nanosac is produced by sequential coating of mesoporous silica nanoparticles (MSNs) with siRNA and polydopamine, followed by removal of the sacrificial MSN core. The Nanosac recruits serum albumin, co-opts caveolae-mediated endocytosis to enter tumor cells, and efficiently silences target genes. The softness of Nanosac improves extravasation and penetration into tumors compared to its hard counterpart. As a carrier of siRNA targeting PD-L1, Nanosac induces a significant attenuation of CT26 tumor growth by immune checkpoint blockade. These results support the utility of Nanosac in the systemic delivery of siRNA for solid tumor therapy.

Optimizing the use of topical brimonidine in rosacea management: panel recommendations.

Rosacea is a chronic inflammatory disease with a complex pathophysiology that manifests with central facial redness with or without papulopustular lesions. Often, patients with rosacea present with a constellation of signs and symptoms; for best results, the treatment plan should take into account all symptoms manifesting in the individual patient. The first available pharmacologic treatment to address the redness associated with rosacea is topical brimonidine. In the United States, brimonidine topical gel 0.33% is indicated for persistent facial erythema of rosacea; approval was based on clinically significant efficacy and good safety data from large-scale clinical trials. Use of brimonidine in routine clinical practice has yielded new insights that elaborate on the findings from clinical trials. For example, real-world use has shown that a percentage of patients (in our experience, approximately 10 to 20%) treated with brimonidine experience a worsening of erythema that has been called "rebound." Our routine use of this agent for >1 year has yielded strategies to set patient expectations, optimize treatment initiation, and minimize potential problems; this article details those strategies. Because we believe that the term "rebound" has been used to describe several physiologically distinct events, we have also proposed more specific terminology for such events.