Transforming Growth Factor-ß Blockade in Pancreatic Cancer Enhances Sensitivity to Combination Chemotherapy.

BACKGROUND & AIMS: Transforming growth factor-b (TGFb) plays pleiotropic roles in pancreatic cancer, including promoting metastasis, attenuating CD8 T-cell activation, and enhancing myofibroblast differentiation and deposition of extracellular matrix. However, single-agent TGFb inhibition has shown limited efficacy against pancreatic cancer in mice or humans. METHODS: We evaluated the TGFß-blocking antibody NIS793 in combination with gemcitabine/nanoparticle (albumin-bound)-paclitaxel or FOLFIRINOX (folinic acid [FOL], 5-fluorouracil [F], irinotecan [IRI] and oxaliplatin [OX]) in orthotopic pancreatic cancer models. Single-cell RNA sequencing and immunofluorescence were used to evaluate changes in tumor cell state and the tumor microenvironment. RESULTS: Blockade of TGFß with chemotherapy reduced tumor burden in poorly immunogenic pancreatic cancer, without affecting the metastatic rate of cancer cells. Efficacy of combination therapy was not dependent on CD8 T cells, because response to TGFß blockade was preserved in CD8-depleted or recombination activating gene 2 (RAG2-/-) mice. TGFß blockade decreased total α-smooth muscle actin-positive fibroblasts but had minimal effect on fibroblast heterogeneity. Bulk RNA sequencing on tumor cells sorted ex vivo revealed that tumor cells treated with TGFß blockade adopted a classical lineage consistent with enhanced chemosensitivity, and immunofluorescence for cleaved caspase 3 confirmed that TGFß blockade increased chemotherapy-induced cell death in vivo. CONCLUSIONS: TGFß regulates pancreatic cancer cell plasticity between classical and basal cell states. TGFß blockade in orthotropic models of pancreatic cancer enhances sensitivity to chemotherapy by promoting a classical malignant cell state. This study provides scientific rationale for evaluation of NIS793 with FOLFIRINOX or gemcitabine/nanoparticle (albumin-bound) paclitaxel chemotherapy backbone in the clinical setting and supports the concept of manipulating cancer cell plasticity to increase the efficacy of combination therapy regimens.

[Cholangiocarcinoma and combined hepatocellular-cholangiocarcinoma in cirrhotic patients]. / Colangiocarcinoma y hepatocolangiocarcinoma combinado en pacientes con cirrosis.

BACKGROUND: Cholangiocarcinoma (CCA) is a primary hepatic tumor, frequently found in patients with liver cirrhosis and biliary tract diseases. Its varieties include isolated CCA or "combined hepatocellular-cholangiocarcinoma" (cHCC-CCA). The latter is uncommon, with poorly defined diagnostic criteria and natural history. AIM: To characterize patients with cirrhosis with a pathological diagnosis of CCA and cHCC-CCA. MATERIAL AND METHODS: Forty-nine liver biopsies with a pathological diagnosis of CCA were reviewed. The clinical records of patients were reviewed to fetch demographic variables, etiology of cirrhosis and clinical presentation. RESULTS: Eight of the 49 patients had cirrhosis (16% of CCA biopsies reviewed). Their median age was 64 (27-71) years and five were females. Four patients had CCA, three patients cHCC-CCA and one had a bifocal tumor. Patients in the CCA group were more commonly symptomatic. Alpha-fetoprotein and CA 19-9 levels were elevated in one of eight and four of six patients, respectively. Within 12 months from diagnosis, five of eight patients died. CONCLUSIONS: In most of these cases, the diagnosis of cHCC-CCA and CCA was made in the liver explant study without previous imaging diagnosis. This reinforces the usefulness of the histological study, in specific cases, prior to liver transplantation and emphasizes the importance of systematic explant exploration in these cases.

Genetic fingerprinting and aflatoxin production of Aspergillus section Flavi associated with groundnut in eastern Ethiopia.

BACKGROUND: Aspergillus species cause aflatoxin contamination in groundnut kernels, being a health threat in agricultural products and leading to commodity rejection by domestic and international markets. Presence of Aspergillus flavus and A. parasiticus colonizing groundnut in eastern Ethiopia, as well as presence of aflatoxins have been reported, though in this region, no genetic studies have been done of these species in relation to their aflatoxin production. RESULTS: In this study, 145 Aspergillus isolates obtained from groundnut kernels in eastern Ethiopia were genetically fingerprinted using 23 Insertion/Deletion (InDel) markers within the aflatoxin-biosynthesis gene cluster (ABC), identifying 133 ABC genotypes. Eighty-four isolates were analyzed by Ultra-Performance Liquid Chromatography (UPLC) for in vitro aflatoxin production. Analysis of genetic distances based on the approximately 85 kb-ABC by Neighbor Joining (NJ), 3D-Principal Coordinate Analysis (3D-PCoA), and Structure software, clustered the isolates into three main groups as a gradient in their aflatoxin production. Group I, contained 98% A. flavus, including L- and non-producers of sclerotia (NPS), producers of B1 and B2 aflatoxins, and most of them collected from the lowland-dry Babile area. Group II was a genetic admixture population of A. flavus (NPS) and A. flavus S morphotype, both low producers of aflatoxins. Group III was primarily represented by A. parasiticus and A. flavus S morphotype isolates both producers of B1, B2 and G1, G2 aflatoxins, and originated from the regions of Darolabu and Gursum. The highest in vitro producer of aflatoxin B1 was A. flavus NPS N1436 (77.98 µg/mL), and the highest producer of aflatoxin G1 was A. parasiticus N1348 (50.33 µg/mL), these isolates were from Gursum and Darolabu, respectively. CONCLUSIONS: To the best of our knowledge, this is the first study that combined the use of InDel fingerprinting of the ABC and corresponding aflatoxin production capability to describe the genetic diversity of Aspergillus isolates from groundnut in eastern Ethiopia. Three InDel markers, AFLC04, AFLC08 and AFLC19, accounted for the main assignment of individuals to the three Groups; their loci corresponded to aflC (pksA), hypC, and aflW (moxY) genes, respectively. Despite InDels within the ABC being often associated to loss of aflatoxin production, the vast InDel polymorphism observed in the Aspergillus isolates did not completely impaired their aflatoxin production in vitro.

[Surgical complications in cirrhotic patients. Analysis of 102 cases]. / Cirugía en el paciente cirrótico: características clínicas y complicaciones en una cohorte de pacientes chilenos.

BACKGROUND: Cirrhotic patients have an increased surgical risk due to potential intra and postoperative complications. AIM: To describe the clinical characteristics and surgical complications of cirrhotic patients undergoing surgery in a Chilean university hospital. PATIENTS AND METHODS: Review of medical records of 102 cirrhotic patients aged 60 ± 11 years (52% males) who underwent elective or urgency surgery at an university hospital between 2010 and 2016. General, pre-surgical, and post-surgical complications were recorded. RESULTS: The main etiologies of cirrhosis were non-alcoholic steatohepatitis (31%), and alcoholic cirrhosis (28%). Child-Pugh scores were A, B and C in 50, 28 and 22% of cases respectively. Median MELD (Model for End-stage Liver Disease) score was 11 (interquartile range: 10-15). The surgical procedure was elective in 71% of cases, with predominance of abdominal surgery (86%). The American Society of Anesthesiologists (ASA) score was three or more in 52% of patients. The frequency of any adverse outcome was 62%. The frequency increased along with the severity of cirrhosis and when surgery was urgent. The most common complications were acute renal failure (24%), increased ascites (23%) and encephalopathy (22%). Admission to intensive care unit occurred on 26% of patients, with six hospital deaths. CONCLUSIONS: In these patients, surgical complications were common, although with low mortality.

Antimicrobial synergy between mRNA targeted peptide nucleic acid and antibiotics in E. coli.

A combination of antibacterial agents should make the emergence of resistance in bacteria less probable. Thus we have analyzed the synergistic effects between antibacterial antisense peptide nucleic acids (PNA) and conventional antibiotics against Escherichia coli AS19 (lipopolysaccharide defective) strain and a derivative of a pathogenic strain E. coli O157:H7. PNAs were designed to target mRNA transcripts encoding the essential acyl carrier protein (gene acpP) and conjugated to the cell-penetrating peptide (KFF)3K for cellular uptake. Antibiotics included aminoglycosides, aminopenicillins, polymyxins, rifamycins, sulfonamides and trimethoprim. Synergies were evaluated using the checkerboard technique. Fractional Inhibitory Concentration indices (FICi) were calculated for all combinations based on the minimal inhibitory concentration of each individual agent. The results demonstrate two novel synergistic combinations of antimicrobial agents, namely, (KFF)3K-PNA anti-acpP with polymyxin B and (KFF)3K-PNA anti-acpP with trimethoprim (both with FICi = 0.38). Polymyxin B's synergy postulates cell wall targeted antibiotics as attractive agents to improve the uptake of PNA while trimethoprim's interaction with PNA my reveal a new inhibitory mechanism.

Study of the genetic diversity of the aflatoxin biosynthesis cluster in Aspergillus section Flavi using insertion/deletion markers in peanut seeds from Georgia, USA.

Aflatoxins are among the most powerful carcinogens in nature. The major aflatoxin-producing fungi are Aspergillus flavus and A. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow that allowed prescreening of 238 Aspergillus section Flavi isolates from peanut seeds from Georgia, USA. The aflatoxin biosynthesis cluster (ABC) of the isolates was fingerprinted at 25 InDel (insertion/deletion) loci using capillary electrophoresis. All isolates were tested for aflatoxins using ultra-high-performance liquid chromatography. The neighbor-joining, three-dimension (3D) principal coordinate, and Structure analyses revealed that the Aspergillus isolates sampled consisted of three main groups determined by their capability to produce aflatoxins. Group I comprised 10 non-aflatoxigenic A. flavus; Group II included A. parasiticus; and Group III included mostly aflatoxigenic A. flavus and the three non-aflatoxigenic A. caelatus. Whole genomes of 10 representative isolates from different groups were sequenced. Although InDels in Aspergillus have been used by other research groups, this is the first time that the cluster analysis resulting from fingerprinting was followed by whole-genome sequencing of representative isolates. In our study, cluster analysis of ABC sequences validated the results obtained with fingerprinting. This shows that InDels used here can predict similarities at the genome level. Our results also revealed a relationship between groups and their capability to produce aflatoxins. The database generated of Aspergillus spp. can be used to select target genes and assess the effectiveness of RNAi technology to reduce aflatoxin contamination in peanut.

Recent Advances of MEMS Resonators for Lorentz Force Based Magnetic Field Sensors: Design, Applications and Challenges.

Microelectromechanical systems (MEMS) resonators have allowed the development of magnetic field sensors with potential applications such as biomedicine, automotive industry, navigation systems, space satellites, telecommunications and non-destructive testing. We present a review of recent magnetic field sensors based on MEMS resonators, which operate with Lorentz force. These sensors have a compact structure, wide measurement range, low energy consumption, high sensitivity and suitable performance. The design methodology, simulation tools, damping sources, sensing techniques and future applications of magnetic field sensors are discussed. The design process is fundamental in achieving correct selection of the operation principle, sensing technique, materials, fabrication process and readout systems of the sensors. In addition, the description of the main sensing systems and challenges of the MEMS sensors are discussed. To develop the best devices, researches of their mechanical reliability, vacuum packaging, design optimization and temperature compensation circuits are needed. Future applications will require multifunctional sensors for monitoring several physical parameters (e.g., magnetic field, acceleration, angular ratio, humidity, temperature and gases).

Domestication of small-seeded lima bean (Phaseolus lunatus L.) landraces in Mesoamerica: evidence from microsatellite markers.

Previous studies have suggested that the Mesoamerican small-seeded landraces of Lima bean may have been domesticated more than once in Mesoamerica, once in central-western Mexico and another one in an area between Guatemala and Costa Rica. However, these findings were based on sequencing of only one locus from nuclear DNA, and additional confirmation was needed. Here we contribute with additional data on the origin of the Mesoamerican landraces and document the founder effect due to domestication. We characterized 62 domesticated, 87 wild and six weedy Lima bean accessions with ten microsatellite loci. Genetic relationships were analyzed using genetic distances and Bayesian clustering approaches. Domestication bottlenecks were documented using inter-population comparisons and M ratios. The results support at least one domestication event in the area of distribution of gene pool MI in central-western Mexico and also show that some landraces are genetically related to wild accessions of gene pool MII. Also, our data support founder effects due to domestication in Mesoamerican Lima bean landraces. Although we could not establish more specifically the place of origin of the Mesoamerican Lima bean landraces, our results show that these are not a genetically homogeneous group, a finding that may be compatible with a scenario of more than one domestication event accompanied by gene flow. The complex genetic makeup of landraces that we found indicates that a more comprehensive geographic and genomic sampling is needed in order to establish how domestication processes and gene flow have shaped the current genetic structure of landraces.

Development of a Large Set of Microsatellite Markers in Zapote Mamey (Pouteria sapota (Jacq.) H.E. Moore & Stearn) and Their Potential Use in the Study of the Species.

Pouteria sapota is known for its edible fruits that contain unique carotenoids, as well as for its fungitoxic, anti-inflammatory and anti-oxidant activity. However, its genetics is mostly unknown, including aspects about its genetic diversity and domestication process. We did high-throughput sequencing of microsatellite-enriched libraries of P. sapota, generated 5223 contig DNA sequences, 1.8 Mbp, developed 368 microsatellites markers and tested them on 29 individuals from 10 populations (seven wild, three cultivated) from Mexico, its putative domestication center. Gene ontology BLAST analysis of the DNA sequences containing microsatellites showed potential association to physiological functions. Genetic diversity was slightly higher in cultivated than in the wild gene pool (HE = 0.41 and HE = 0.35, respectively), although modified Garza-Williamson Index and Bottleneck software showed evidence for a reduction in genetic diversity for the cultivated one. Neighbor Joining, 3D Principal Coordinates Analysis and assignment tests grouped most individuals according to their geographic origin but no clear separation was observed between wild or cultivated gene pools due to, perhaps, the existence of several admixed populations. The developed microsatellites have a great potential in genetic population and domestication studies of P. sapota but additional sampling will be necessary to better understand how the domestication process has impacted the genetic diversity of this fruit crop.

[Spontaneous clearance of hepatitis C virus after liver transplantation: Report of two cases]. / Eliminación espontánea de virus hepatitis C en trasplantado hepático: a propósito de dos casos.

The spontaneous clearance of hepatitis C virus infection is rare, especially after liver transplantation, condition in which recurrence is almost universal. We report two cases in which clearance of the virus was achieved after liver transplantation. We reviewed the literature and described possible mechanisms explaining this phenomenon, with emphasis on therapeutic implications.

[Skin manifestations in adults with a liver allograft]. / Manifestaciones cutáneas en adultos con trasplante hepático del Hospital Clínico de la Universidad de Chile.

BACKGROUND: Skin manifestations after liver transplantation are increasing due to long term immunosuppressive therapy along with an increase in patient survival. Several studies have reported dermatologic complications following renal transplant, but few have studied dermatologic problems after liver transplantation. AIMS: To describe the different types of cutaneous lesions encountered in adults receiving a liver allograft. To evaluate the frequency of cutaneous manifestations of patients in the liver transplant waiting list. MATERIAL AND METHODS: Eighty patients submitted to a liver transplant and 70 patients in the liver transplant waiting list were evaluated with a complete dermatological physical examination. RESULTS: Sixty one percent of patients with a liver allograft had at least one skin manifestation. Of these, 34% had superficial fungal infections, 31% had viral infections, 20% had cutaneous side effects due to immunosuppressive treatment, 10% had malignant lesions, 2% had bacterial infections and one patient had a graft versus host disease. Only 28% of patients in the liver transplant waiting list had dermatologic problems, and the vast majority were lesions linked to liver cirrhosis. CONCLUSIONS: Cutaneous infections were the most common skin problems in liver transplant patients. Although neoplastic lesions are the most commonly mentioned lesions in the literature, only a 10% of our liver transplant patients presented these type of lesions.

Genetic structure within the Mesoamerican gene pool of wild Phaseolus lunatus (Fabaceae) from Mexico as revealed by microsatellite markers: Implications for conservation and the domestication of the species.

UNLABELLED: • PREMISE OF THE STUDY: Understanding genetic structure in wild relatives of a crop is important for crop improvement and conservation. Recently, two gene pools (MI and MII) were reported in wild Lima bean (Phaseolus lunatus) from Mexico, a domestication center of Mesoamerican landraces. However, the evidence was based on limited genomic sampling. Here we sought to confirm the existence of these two gene pools by increased genome and population sampling.• METHODS: We characterized 67 wild populations of P. lunatus from Mexico with 10 microsatellite loci and studied the genetic structure by means of AMOVA, cluster analyses, assignment tests, and a georeferenced map.• KEY RESULTS: AMOVA indicated that most of the variation is found among populations (77%) rather than within populations (23%). Assignment tests were key to confirm not only the presence of the two gene pools (MI and MII) in Mexico, but also to propose the possible existence of two subgroups within MI (MIa and MIb). While MI and MII are mainly divergent geographically, MIa and MIb overlap in their distribution. Admixed individuals, which may represent cases of gene flow among gene pools, were detected.• CONCLUSIONS: Our results show that the genetic structure of wild Lima bean in Mexico is more complex than previously thought and propose the presence of three gene pools (MIa, MIb, and MII), each one possessing relatively high levels of genetic diversity. We still need additional evidence, however, to confirm without doubt the split of the gene pool MI into subgroups MIa and MIb.

Simplified Models to Assess the Mechanical Performance Parameters of Stents.

Ischemic heart disease remains a leading cause of mortality worldwide, which has promoted extensive therapeutic efforts. Stenting has emerged as the primary intervention, particularly among individuals aged 70 years and older. The geometric specifications of stents must align with various mechanical performance criteria outlined by regulatory agencies such as the Food and Drug Administration (FDA). Finite element method (FEM) analysis and computational fluid dynamics (CFD) serve as essential tools to assess the mechanical performance parameters of stents. However, the growing complexity of the numerical models presents significant challenges. Herein, we propose a method to determine the mechanical performance parameters of stents using a simplified FEM model comprising solid and shell elements. In addition, a baseline model of a stent is developed and validated with experimental data, considering parameters such as foreshortening, radial recoil, radial recoil index, and radial stiffness of stents. The results of the simplified FEM model agree well with the baseline model, decreasing up to 80% in computational time. This method can be employed to design stents with specific mechanical performance parameters that satisfy the requirements of each patient.

Eco-friendly, compact, and cost-efficient triboelectric nanogenerator for renewable energy harvesting and smart motion sensing.

In recent years, the growth of Internet of Things devices has increased the use of sustainable energy sources. An alternative technology is offered by triboelectric nanogenerators (TENGs) that can harvest green energy and convert it into electrical energy. Herein, we assessed three different nopal powder types that were used as triboelectric layers of eco-friendly and sustainable TENGs for renewable energy harvesting from environmental vibrations and powering electronic devices. These nanogenerators were fabricated using waste and recycled materials with a compact design for easy transportation and collocation on non-homogeneous surfaces of different vibration or motion sources. In addition, these TENGs have advantages such as high output performance, stable output voltage, lightweight, low-cost materials, and a simple fabrication process. These nanogenerators use the contact-separation mode between two triboelectric layers to convert the vibration energy into electrical energy. TENG with the best output performance is based on dehydrated nopal powder, generating an output power density of 2.145 mWm-2 with a load resistance of 39.97 MΩ under 3g acceleration and 25 Hz operating frequency. The proposed TENGs have stable output voltages during 22500 operating cycles. These nanogenerators can light 116 ultra-bright blue commercial LEDs and power a digital calculator. Also, the TENGs can be used as a chess clock connected to a mobile phone app for smart motion sensing. These nanogenerators can harvest renewable vibration energy and power electronic devices, sensors, and smart motion sensing.

[Ménétrier disease. Report of one case]. / Enfermedad de Ménétrier con compromiso gástrico difuso y duodenal: Caso clínico.

BACKGROUND: Ménétrier disease is a rare disorder of the stomach, characterized by giant hypertrophic folds that usually involve the gastric body and fundus, associated to hypoalbuminemia due to serum protein loss across the gastric mucosa. We report a 55-years-old male presenting with abdominal pain, vomiting, weight loss and hypoalbuminemia. Diffuse hypertrophic gastric folds, elevated ulcerated sessile lesions and focal duodenal involvement were seen at endoscopy. Biopsies showed foveolar hyperplasia and glandular atrophy with cystic dilatation. A total gastrectomy was performed with a good outcome.

[Hepatitis B virus immunoglobulin on demand to prevent infection recurrence among liver allograft recipients: report of three cases]. / Trasplante hepático en cirrosis por virus B: profilaxis con gammaglobulina antiHBs en dosis a "demanda".

Infection recurrence rates among hepatitis B virus infected liver allograft recipients, may be as high as 80%. Immunoprophylaxis with anti HBVgammaglobulin may reduce these rates and improve survival. The dose of anti HBV gammaglobulin that must be used is not clearly defined. The most commonly accepted protocol uses 10,000 units during the anhepatic phase and 10,000 units daily during one week, followed by weekly doses of 10,000 units during one month and maintenance with 10,000 units monthly, without measuring anti hepatitis B surface antigen antibodies (antiHBs). Some reports recommend the use of immunoglobulin on demand, to maintain antiHBs titers between 100 and 250 U/l. The infection recurrence rates among patients treated with immunoglobulin and Lamivudine fluctuates between 0 and 10%, during follow up periods of 13 to 30 months. We report three liver allograft recipients that received immunoglobulin on demand, using a mean of 41,000 units, maintaining adequate antiHBs titers.

Consequences of introgression and gene flow on the genetic structure and diversity of Lima bean (Phaseolus lunatus L.) in its Mesoamerican diversity area.

We evaluated the role of gene flow and wild-crop introgression on the structure and genetic diversity of Lima bean (Phaseolus lunatus) in the Yucatan Peninsula, an important Mesoamerican diversity area for this crop, using a genotyping-by-sequencing approach (15,168 SNP markers) and two scales. At the local scale, STRUCTURE and NGSEP analyses showed predominantly crop-to-wild introgression, but also evidence of a bidirectional gene flow in the two wild-weedy-crop complexes studied (Itzinté and Dzitnup). The ABBA-BABA tests showed a higher introgression in Itzinté (the older complex) than in Dzitnup (the younger one); at the allelic level, the wild-crop introgression in Itzinté was similar in both directions, in Dzitnup it was higher from crop-to-wild; and at the chromosomal level, introgression in Itzinté was from wild-to-crop, whereas in Dzitnup it occured in the opposite direction. Also, we found H E values slightly higher in the domesticated accessions than in the wild ones, in both complexes (Itzinté: wild = 0.31, domesticated = 0.34; Dzinup: wild = 0.27, domesticated = 0.36), but %P and π estimators were higher in the wild accessions than in the domesticated ones. At a regional scale, STRUCTURE and MIGRATE showed a low gene flow, predominantly from crop-to-wild; and STRUCTURE, Neighbor-Joining and PCoA analyses indicated the existence of two wild groups and one domesticated group, with a marked genetic structure based in the existence of domesticated MI and wild MII gene pools. Also, at the regional scale, we found a higher genetic diversity in the wild accessions than in the domesticated ones, in all estimators used (e.g., H E = 0.27 and H E = 0.17, respectively). Our results indicate that gene flow and introgression are playing an important role at the local scale, but its consequences on the structure and genetic diversity of the Lima bean are not clearly reflected at the regional scale, where diversity patterns between wild and domesticated populations could be reflecting historical events.

Triboelectric and Piezoelectric Nanogenerators for Self-Powered Healthcare Monitoring Devices: Operating Principles, Challenges, and Perspectives.

The internet of medical things (IoMT) is used for the acquisition, processing, transmission, and storage of medical data of patients. The medical information of each patient can be monitored by hospitals, family members, or medical centers, providing real-time data on the health condition of patients. However, the IoMT requires monitoring healthcare devices with features such as being lightweight, having a long lifetime, wearability, flexibility, safe behavior, and a stable electrical performance. For the continuous monitoring of the medical signals of patients, these devices need energy sources with a long lifetime and stable response. For this challenge, conventional batteries have disadvantages due to their limited-service time, considerable weight, and toxic materials. A replacement alternative to conventional batteries can be achieved for piezoelectric and triboelectric nanogenerators. These nanogenerators can convert green energy from various environmental sources (e.g., biomechanical energy, wind, and mechanical vibrations) into electrical energy. Generally, these nanogenerators have simple transduction mechanisms, uncomplicated manufacturing processes, are lightweight, have a long lifetime, and provide high output electrical performance. Thus, the piezoelectric and triboelectric nanogenerators could power future medical devices that monitor and process vital signs of patients. Herein, we review the working principle, materials, fabrication processes, and signal processing components of piezoelectric and triboelectric nanogenerators with potential medical applications. In addition, we discuss the main components and output electrical performance of various nanogenerators applied to the medical sector. Finally, the challenges and perspectives of the design, materials and fabrication process, signal processing, and reliability of nanogenerators are included.

Recent Progress of Nanogenerators for Green Energy Harvesting: Performance, Applications, and Challenges.

Natural sources of green energy include sunshine, water, biomass, geothermal heat, and wind. These energies are alternate forms of electrical energy that do not rely on fossil fuels. Green energy is environmentally benign, as it avoids the generation of greenhouse gases and pollutants. Various systems and equipment have been utilized to gather natural energy. However, most technologies need a huge amount of infrastructure and expensive equipment in order to power electronic gadgets, smart sensors, and wearable devices. Nanogenerators have recently emerged as an alternative technique for collecting energy from both natural and artificial sources, with significant benefits such as light weight, low-cost production, simple operation, easy signal processing, and low-cost materials. These nanogenerators might power electronic components and wearable devices used in a variety of applications such as telecommunications, the medical sector, the military and automotive industries, and internet of things (IoT) devices. We describe new research on the performance of nanogenerators employing several green energy acquisition processes such as piezoelectric, electromagnetic, thermoelectric, and triboelectric. Furthermore, the materials, applications, challenges, and future prospects of several nanogenerators are discussed.