Self-Assembled Block Copolymers as a Facile Pathway to Create Functional Nanobiosensor and Nanobiomaterial Surfaces.

Block copolymer (BCP) surfaces permit an exquisite level of nanoscale control in biomolecular assemblies solely based on self-assembly. Owing to this, BCP-based biomolecular assembly represents a much-needed, new paradigm for creating nanobiosensors and nanobiomaterials without the need for costly and time-consuming fabrication steps. Research endeavors in the BCP nanobiotechnology field have led to stimulating results that can promote our current understanding of biomolecular interactions at a solid interface to the never-explored size regimes comparable to individual biomolecules. Encouraging research outcomes have also been reported for the stability and activity of biomolecules bound on BCP thin film surfaces. A wide range of single and multicomponent biomolecules and BCP systems has been assessed to substantiate the potential utility in practical applications as next-generation nanobiosensors, nanobiodevices, and biomaterials. To this end, this Review highlights pioneering research efforts made in the BCP nanobiotechnology area. The discussions will be focused on those works particularly pertaining to nanoscale surface assembly of functional biomolecules, biomolecular interaction properties unique to nanoscale polymer interfaces, functionality of nanoscale surface-bound biomolecules, and specific examples in biosensing. Systems involving the incorporation of biomolecules as one of the blocks in BCPs, i.e., DNA-BCP hybrids, protein-BCP conjugates, and isolated BCP micelles of bioligand carriers used in drug delivery, are outside of the scope of this Review. Looking ahead, there awaits plenty of exciting research opportunities to advance the research field of BCP nanobiotechnology by capitalizing on the fundamental groundwork laid so far for the biomolecular interactions on BCP surfaces. In order to better guide the path forward, key fundamental questions yet to be addressed by the field are identified. In addition, future research directions of BCP nanobiotechnology are contemplated in the concluding section of this Review.

Atomic force microscopy-mediated mechanobiological profiling of complex human tissues.

Tissue mechanobiology is an emerging field with the overarching goal of understanding the interplay between biophysical and biochemical responses affecting development, physiology, and disease. Changes in mechanical properties including stiffness and viscosity have been shown to describe how cells and tissues respond to mechanical cues and modify critical biological functions. To quantitatively characterize the mechanical properties of tissues at physiologically relevant conditions, atomic force microscopy (AFM) has emerged as a highly versatile biomechanical technology. In this review, we describe the fundamental principles of AFM, typical AFM modalities used for tissue mechanics, and commonly used elastic and viscoelastic contact mechanics models to characterize complex human tissues. Furthermore, we discuss the application of AFM-based mechanobiology to characterize the mechanical responses within complex human tissues to track their developmental, physiological/functional, and diseased states, including oral, hearing, and cancer-related tissues. Finally, we discuss the current outlook and challenges to further advance the field of tissue mechanobiology. Altogether, AFM-based tissue mechanobiology provides a mechanistic understanding of biological processes governing the unique functions of tissues.

Elucidation of Strain-Dependent, Zinc Oxide Nanorod Response for Nanorod-Guided Fluorescence Intensity.

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive and tensile strain on the NRs and measured fluorescence intensity of a model fluorophore, rhodamine 6G (R6G), as a function of the position on the NRs. We reveal that compressive strain on the NRs leads to a decrease in the guided fluorescence signal, while tensile strain leads to an increase in the fluorescence intensity. Compared to an unstrained state, approximately 35% decrease (increase) in R6G fluorescence intensity was observed from ZnO NRs when they were under compressive strain of -14% (tensile strain of +10%). Further, our systematic acquisition of the incremental addition of uniaxial strain result in a linear relationship of the coupled fluorescence signal and the amount of applied strain. The degree of fluorescence intensification on nanorod ends (DoF), which is a quantitative indicator for the amount of R6G signals coupled into and waveguided to the NR ends compared to those on the main body, also exhibits a linear relationship with strain. These outcomes, in turn, demonstrate that strain alters the waveguiding capabilities of ZnO NRs in a predictable manner, which can be exploited to modulate and optimize fluorescence and other light signals emitted by a nearby source. Considering the wide utility of ZnO NRs in photonics, optoelectronics, and sensors, insights from our study may be highly valuable to effectively controlling and enhancing optical signals from chemical and biological analytes through strain.

Distinctive Adsorption Mechanism and Kinetics of Immunoglobulin G on a Nanoscale Polymer Surface.

Elucidation of protein adsorption beyond simple polymer surfaces to those presenting greater chemical complexity and nanoscopic features is critical to developing well-controlled nanobiomaterials and nanobiosensors. In this study, we repeatedly and faithfully track individual proteins on the same nanodomain areas of a block copolymer (BCP) surface and monitor the adsorption and assembly behavior of a model protein, immunoglobulin G (IgG), over time into a tight surface-packed structure. With discrete protein adsorption events unambiguously visualized at the biomolecular level, the detailed assembly and packing states of IgG on the BCP nanodomain surface are subsequently correlated to various regimes of IgG adsorption kinetic plots. Intriguing features, entirely different from those observed from macroscopic homopolymer templates, are identified from the IgG adsorption isotherms on the nanoscale, chemically varying BCP surface. They include the presence of two Langmuir-like adsorption segments and a nonmonotonic regime in the adsorption plot. Via correlation to time-corresponding topographic data, the unique isotherm features are explained with single biomolecule level details of the IgG adsorption pathway on the BCP. This work not only provides much needed, direct experimental evidence for time-resolved, single protein level, adsorption events on nanoscale polymer surfaces but also signifies mutual linking between specific topographic states of protein adsorption and assembly to particular segments of adsorption isotherms. From the fundamental research viewpoint, the correlative ability to examine the nanoscopic surface organizations of individual proteins and their local as well as global adsorption kinetic profiles will be highly valuable for accurately determining protein assembly mechanisms and interpreting protein adsorption kinetics on nanoscale surfaces. Application-wise, such knowledge will also be important for fundamentally guiding the design and development of biomaterials and biomedical devices that exploit nanoscale polymer architectures.

Ultrasound-Guided Stellate Ganglion Block With Preserved Motor Function for Upper Extremity Surgery.

While stellate ganglion blockade (SGB) is commonly used in the treatment and management of patients who suffer from chronic pain, we are reporting a case where an ultrasound-guided SGB was used for management of acute perioperative pain for a patient undergoing upper extremity surgery. The patient was classified as the American Society of Anesthesiologists (ASA) class 1, without any significant past medical history, including no history of chronic pain, opioid use, or peripheral neuropathy. The patient was scheduled for tendon repair of the hand following trauma with subsequent lacerations. While general anesthesia, a brachial plexus blockade, or combination of the two are generally used in current practice for upper extremity surgery, these typically do not allow for intraoperative evaluation of motor function. In our case, an ultrasound-guided SGB was used to provide analgesia while still allowing for intraoperative assessment of motor function during the critical components of the repair. This case illustrates the potential advantages of an ultrasound-guided SGB for decreasing acute postoperative pain scores, decreasing overall postoperative pain medication use, as well as maintaining intraoperative motor function in cases where such monitoring may be advantageous and allow for optimal surgical repair.

Protein-Polymer Interaction Characteristics Unique to Nanoscale Interfaces: A Perspective on Recent Insights.

Protein interactions at polymer interfaces represent a complex but ubiquitous phenomenon that demands an entirely different focus of investigation than what has been attempted before. With the advancement of nanoscience and nanotechnology, the nature of polymer materials interfacing proteins has evolved to exhibit greater chemical intricacy and smaller physical dimensions. Existing knowledge built from studying the interaction of macroscopic, chemically alike surfaces with an ensemble of protein molecules cannot be simply carried over to nanoscale protein-polymer interactions. In this Perspective, novel protein interaction phenomena driven by the presence of nanoscale polymer interfaces are discussed. Being able to discern discrete protein interaction events via simple visualization was crucial to attaining the much needed, direct experimental evidence of protein-polymer interactions at the single biomolecule level. Spatial and temporal tracking of particular proteins at specific polymer interfaces was made possible by resolving individual proteins simultaneously with those polymer nanodomains responsible for the protein interactions. Therefore, such single biomolecule level approaches taken to examine protein-polymer interaction mark a big departure from the mainstream approaches of collecting indirectly observed, ensemble-averaged protein signals on chemically simple substrates. Spearheading research efforts so far has led to inspiring initial discoveries of protein interaction mechanisms and kinetics that are entirely unique to nanoscale polymer systems. They include protein self-assembly/packing characteristics, protein-polymer interaction mechanisms/kinetics, and various protein functionalities on polymer nanoconstructs. The promising beginning and future of nanoscale protein-polymer research endeavors are presented in this article.

Unique Considerations for Complete Surgical Analgesia for Below-the-Knee Amputations.

Recent cadaver studies have suggested that posterior femoral cutaneous nerve (PFCN) may contribute to the sensory innervation of the posterior lower leg. Whether this is clinically relevant may be revealed in patients who underwent below-the-knee amputation (BKA) with monitored anesthesia care (MAC) and peripheral nerve blocks. We performed femoral and sciatic nerve blocks for a 55-year-old male patient who underwent BKA and subsequent formalization surgeries as the main surgical analgesia while providing MAC in the operating room. In both cases, the patient could not tolerate surgical incisions in the posteromedial aspect of the lower leg, despite reporting no pain in other areas of the lower leg with surgical stimulation. There may exist a small population of patients in which PFCN makes significant contribution to the sensory innervation of the posterior lower leg. For these patients, the combination of femoral and sciatic nerve blocks may not be adequate in providing surgical analgesia for BKA and related procedures.

Transition metal cation inhibition of Mycobacterium tuberculosis esterase RV0045C.

Mycobacterium tuberculosis virulence is highly metal-dependent with metal availability modulating the shift from the dormant to active states of M. tuberculosis infection. Rv0045c from M. tuberculosis is a proposed metabolic serine hydrolase whose folded stability is dependent on divalent metal concentration. Herein, we measured the divalent metal inhibition profile of the enzymatic activity of Rv0045c and found specific divalent transition metal cations (Cu2+ ≥ Zn2+ > Ni2+ > Co2+ ) strongly inhibited its enzymatic activity. The metal cations bind allosterically, largely affecting values for kcat rather than KM . Removal of the artificial N-terminal 6xHis-tag did not change the metal-dependent inhibition, indicating that the allosteric inhibition site is native to Rv0045c. To isolate the site of this allosteric regulation in Rv0045c, the structures of Rv0045c were determined at 1.8 Å and 2.0 Å resolution in the presence and absence of Zn2+ with each structure containing a previously unresolved dynamic loop spanning the binding pocket. Through the combination of structural analysis with and without zinc and targeted mutagenesis, this metal-dependent inhibition was traced to multiple chelating residues (H202A/E204A) on a flexible loop, suggesting dynamic allosteric regulation of Rv0045c by divalent metals. Although serine hydrolases like Rv0045c are a large and diverse enzyme superfamily, this is the first structural confirmation of allosteric regulation of their enzymatic activity by divalent metals.

Short-term outcomes of pyeloplasty vs. nephrectomy in adult patients with ureteropelvic junction obstruction and differential renal function ≤15.

OBJECTIVES: To compare symptom resolution and short-term renal function after pyeloplasty or nephrectomy in adults with ureteropelvic junction obstruction (UPJO) in poorly functioning renal units (PFRU). METHODS: Retrospective analysis of adult patients with UPJO and differential renal function (DRF) ≤ 15% who underwent laparoscopic pyeloplasty or nephrectomy. Primary endpoints included symptom resolution and estimated glomerular filtration rate (eGFR) at 12 months. Surgical complications were compared between groups. A secondary analysis was performed comparing baseline and postoperative DRF to evaluate the PFRU recovery potential after pyeloplasty. RESULTS: Sixty-three patients were included; 19 underwent pyeloplasty and 44 underwent nephrectomy. The mean age of the cohort was 39.5 ± 13.8 years. Nephrectomy was associated with significantly higher intra-operative blood loss (p = 0.02). Operative time and length of hospital stay were not significantly different between groups. There were three complications in the nephrectomy group, and none in the pyeloplasty group (p = 0.34). Symptom resolution rates were equivalent between groups (73% vs. 76%; p = 0.78). The eGFR variation was not statistically different after pyeloplasty or nephrectomy (+6.2 vs. +0.1 mL/min/1.73m2, respectively; p = 0.18). Patients undergoing pyeloplasty had no significant change in the mean DRF (baseline 9.5 vs. 10%; p = 0.99). CONCLUSION: Pyeloplasty can be considered for selected patients with UPJO in PFRU as an organ-sparing alternative to nephrectomy. Although there was no significant gain in mean DRF, pyeloplasty prevented further functional loss and relieved symptoms in most cases in the short-term with at least the same complication rates of nephrectomy.