Targeted Delivery of Sucrose-Coated Nanocarriers with Chemical Cargoes to the Plant Vasculature Enhances Long-Distance Translocation.

Current practices for delivering agrochemicals are inefficient, with only a fraction reaching the intended targets in plants. The surfaces of nanocarriers are functionalized with sucrose, enabling rapid and efficient foliar delivery into the plant phloem, a vascular tissue that transports sugars, signaling molecules, and agrochemicals through the whole plant. The chemical affinity of sucrose molecules to sugar membrane transporters on the phloem cells enhances the uptake of sucrose-coated quantum dots (sucQD) and biocompatible carbon dots with ß-cyclodextrin molecular baskets (suc-ß-CD) that can carry a wide range of agrochemicals. The QD and CD fluorescence emission properties allowed detection and monitoring of rapid translocation (<40 min) in the vasculature of wheat leaves by confocal and epifluorescence microscopy. The suc-ß-CDs more than doubled the delivery of chemical cargoes into the leaf vascular tissue. Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that the fraction of sucQDs loaded into the phloem and transported to roots is over 6.8 times higher than unmodified QDs. The sucrose coating of nanoparticles approach enables unprecedented targeted delivery to roots with ≈70% of phloem-loaded nanoparticles delivered to roots. The use of plant biorecognition molecules mediated delivery provides an efficient approach for guiding nanocarriers containing agrochemicals to the plant vasculature and whole plants.

Flash NanoPrecipitation as an Agrochemical Nanocarrier Formulation Platform: Phloem Uptake and Translocation after Foliar Administration.

The increasing severity of pathogenic and environmental stressors that negatively affect plant health has led to interest in developing next-generation agrochemical delivery systems capable of precisely transporting active agents to specific sites within plants. In this work, we adapt Flash NanoPrecipitation (FNP), a scalable nanocarrier (NC) formulation technology used in the pharmaceutical industry, to prepare organic core-shell NCs and study their efficacy as foliar or root delivery vehicles. NCs ranging in diameter from 55 to 200 nm, with surface zeta potentials from -40 to +40 mV, and with seven different shell material properties were prepared and studied. Shell materials included synthetic polymers poly(acrylic acid), poly(ethylene glycol), and poly(2-(dimethylamino)ethyl methacrylate), naturally occurring compounds fish gelatin and soybean lecithin, and semisynthetic hydroxypropyl methylcellulose acetate succinate (HPMCAS). NC cores contained a gadolinium tracer for tracking by mass spectrometry, a fluorescent dye for tracking by confocal microscopy, and model hydrophobic compounds (alpha tocopherol acetate and polystyrene) that could be replaced by agrochemical payloads in subsequent applications. After foliar application onto tomato plants with Silwet L-77 surfactant, internalization efficiencies of up to 85% and NC translocation efficiencies of up to 32% were observed. Significant NC trafficking to the stem and roots suggests a high degree of phloem loading for some of these formulations. Results were corroborated by confocal microscopy and synchrotron X-ray fluorescence mapping. NCs stabilized by cellulosic HPMCAS exhibited the highest degree of translocation, followed by formulations with a significant surface charge. The results from this work indicate that biocompatible materials like HPMCAS are promising agrochemical delivery vehicles in an industrially viable pharmaceutical nanoformulation process (FNP) and shed light on the optimal properties of organic NCs for efficient foliar uptake, translocation, and delivery.

Temperature-Responsive Bottlebrush Polymers Deliver a Stress-Regulating Agent In Vivo for Prolonged Plant Heat Stress Mitigation.

Anticipated increases in the frequency and intensity of extreme temperatures will damage crops. Methods that efficiently deliver stress-regulating agents to crops can mitigate these effects. Here, we describe high aspect ratio polymer bottlebrushes for temperature-controlled agent delivery in plants. The foliar-applied bottlebrush polymers had near complete uptake into the leaf and resided in both the apoplastic regions of the leaf mesophyll and in cells surrounding the vasculature. Elevated temperature enhanced the in vivo release of spermidine (a stress-regulating agent) from the bottlebrushes, promoting tomato plant (Solanum lycopersicum) photosynthesis under heat and light stress. The bottlebrushes continued to provide protection against heat stress for at least 15 days after foliar application, whereas free spermidine did not. About 30% of the ∼80 nm short and ∼300 nm long bottlebrushes entered the phloem and moved to other plant organs, enabling heat-activated release of plant protection agents in phloem. These results indicate the ability of the polymer bottlebrushes to release encapsulated stress relief agents when triggered by heat to provide long-term protection to plants and the potential to manage plant phloem pathogens. Overall, this temperature-responsive delivery platform provides a new tool for protecting plants against climate-induced damage and yield loss.

Portable X-ray fluorescence for autonomous in-situ characterization of chloride in oil and gas waste.

Soil salinization resulting from anthropogenic activities affects soil health and productivity. Methods that can provide rapid, inexpensive, and accurate salinity characterization over vast areas of soil and waste materials will help in managing their impacts. The objective of this work was to evaluate the accuracy and precision of portable X-ray Fluorescence (pXRF) Cl- measurements of highly saline waste material (WMs) from oil and gas production sites. We compared pXRF Cl- measurements of three unconsolidated WMs to a standard laboratory method for determining soil salinity and identified the WM properties that most affect the precision and accuracy of the pXRF Cl- measurement. Despite covering a range of several orders of magnitude in chloride concentration, calibrated pXRF measurements varied by no more than 14% compared to standard laboratory Cl- measurements for dry homogenous samples. Measurements taken of WMs that were not homogenized decreased pXRF accuracy by 75% while moisture content decreased accuracy by 15%. Field measurements made at different areas inside an oil and gas WM pit were accurate within 60% of the standard laboratory Cl- measurements, despite the samples having a wide range of moisture content and particle size distributions. This study indicates that pXRF can be used to rapidly characterize soil salinity in-situ with acceptable accuracy and precision for screening purposes, opening the door for automated robotic measurements of chloride over large areas.

Quantification of carboxyl-functionalized multiwall carbon nanotubes in plant tissues with programmed thermal analysis.

In this study, carboxyl functionalized multiwall carbon nanotubes (c-MWCNTs) in plant (lettuce [Lactuca sativa Bionda Ricciolina]) tissues were quantitatively analyzed with programmed thermal analysis coupled with a sequential digestion. Programmed thermal analysis evidenced a linear relationship between c-MWCNT-bound C and elemental C detected. A detection limit of 114-708 µg C g-1 plant tissues (dry mass) was achieved for analysis of c-MWCNTs. The method was demonstrated using the tissues of lettuce cultured hydroponically for 3 wk with c-MWCNTs at an exposure of 10 and 20 µg ml-1 . This quantitative analysis can be used to provide insights into carbon nanotube exposure through agricultural products and promote its sustainable application.

Multifocal 1064 nm Raman imaging of carbon nanotubes.

We show that multifocal 1064 nm Raman microscopy based on Hadamard-coded multifocal arrays is useful for imaging carbon nanotubes (CNTs) that would otherwise be damaged if a conventional single focus microscope design is used. The damage threshold for CNTs, dependent on laser power density and exposure time, limits the spectral detection sensitivity of single focus Raman imaging. With multifocal detection, the signal-to-noise ratio of the Raman spectra were improved by more than a factor of three, allowing for the G and D Raman bands of CNTs to be detected while avoiding specimen damage. These results lay the foundation for developing multifocal 1064 nm Raman microscopy as a tool for in situ imaging of CNTs in plant material.

Therapy with a Selective Cannabinoid Receptor Type 2 Agonist Limits Albuminuria and Renal Injury in Mice with Type 2 Diabetic Nephropathy.

BACKGROUND/AIMS: A critical involvement of the endocannabinoid/cannabinoid receptor system in diabetes and its complications has been recognized. Experimental evidence suggested that activation of the cannabinoid receptor type 2 (CB2), which is expressed in the kidney by podocytes and inflammatory cells, had a protective role in early streptozotocin-induced type 1 diabetes in mice. No experimental evidence is so far available on the effects of CB2 agonists in type 2 diabetes. In this study, we investigated the effects of a CB2 agonist given at a phase of overt disease on renal functional and structural changes in BTBR ob/ob mice, a model of type 2 diabetic nephropathy. METHODS: BTBR ob/ob mice received, from 10 to 21 weeks of age, vehicle, the selective CB2 agonist HU910, or lisinopril used as standard therapy for comparison. BTBR wild-type mice served as controls. RESULTS: Treatment with CB2 agonist reduced progressive albuminuria of BTBR ob/ob mice to a similar extent as ACE inhibitor. The antiproteinuric effect of CB2 agonist was associated with the amelioration of the defective nephrin expression in podocytes of diabetic mice. CB2 agonist limited mesangial matrix expansion, fibronectin accumulation and sclerosis. Glomerular infiltration of Mac-2-positive monocytes/machrophages was attenuated by CB2 agonist, at least in part due to the drug's ability to reduce MCP-1 chemotactic signals. Renoprotective effects of CB2 were similar to those achieved by ACE inhibitor. CONCLUSION: These results suggest that CB2 agonism is a potential option to be added to the available therapeutic armamentarium for type 2 diabetic nephropathy.

Analogs of bardoxolone methyl worsen diabetic nephropathy in rats with additional adverse effects.

Bardoxolone methyl is an antioxidant inflammation modulator acting through induction of Keap1-Nrf2 pathway. Results from a recent phase IIb clinical trial reported that bardoxolone methyl was associated with improvement in the estimated glomerular filtration rate in patients with advanced chronic kidney disease and Type 2 diabetes. However, increases in albuminuria, serum transaminase, and frequency of adverse events were noted. We studied the effect of 3-mo treatment with RTA 405, a synthetic triterpenoid analog of bardoxolone methyl in Zucker diabetic fatty rats with overt Type 2 diabetes. Rats were treated from 3 mo of age with vehicle, RTA 405, ramipril, or RTA 405 plus ramipril. RTA 405 caused severe changes in food intake and diuresis with decline in body weight, worsening of dyslipidemia, and increase in blood pressure. Early elevation in serum transaminase was followed by liver injury. RTA 405 worsened proteinuria, glomerulosclerosis, and tubular damage. Ramipril was renoprotective, but when given with RTA 405 it was not able to limit its worsening effects. These data could be due to degradation products in the drug substance used, as disclosed by the company once the study was concluded. To overcome such a drawback, the company offered to test dh404, a variant of RTA 405, in Zucker diabetic fatty rats. The dh404 did not display beneficial effects on proteinuria, glomerulosclerosis, and interstitial inflammation. Rather, kidneys from three rats receiving dh404 showed the presence of a granulomatous and inflammatory process reminiscent of a pseudotumor. Altogether these data raise serious concerns on the use of bardoxolone analogs in Type 2 diabetic nephropathy.

Acute liver rejection: accuracy and predictive values of doppler US measurements--initial experience.

PURPOSE: To prospectively evaluate accuracy and predictive values of Doppler ultrasonographic (US) measurement of portal blood velocity (PBV) and splenic pulsatility index (SPI) in diagnosis of clinically relevant acute rejection in patients with clinicobiochemical hepatic dysfunction after orthotopic liver transplantation (OLT). MATERIALS AND METHODS: Study was approved by the institutional review board, and protocol conformed to ethical guidelines of Declaration of Helsinki. Patient informed consent was obtained. In 27 patients with OLT (23 men, four women; mean age, 48 years; range, 27-64 years), PBV and SPI were measured at Doppler US within 48 hours before or after liver biopsy for clinically suspected acute rejection. Biopsy specimens were assigned scores according to Banff method, and rejection activity index (RAI) was calculated. RAI score of 4 or greater was considered clinically relevant acute rejection. Doppler US parameters were analyzed as absolute values and as percentage point changes with respect to values obtained at last examination before rejection was suspected. Information from two Doppler US parameters was combined; Doppler US composite index was calculated. Statistical tests were conducted to assess accuracy, sensitivity, specificity, and predictive values of Doppler US parameters in diagnosis of graft rejection. RESULTS: Clinically relevant acute rejection was diagnosed in nine patients. Median time from OLT until histologic diagnosis of acute rejection was 8 days (range, 5-20 days). Rejection was associated with a marked reduction in mean PBV (-43% +/- 5 [standard error of the mean]) and a slight increase in SPI (+12% +/- 16). The calculated Doppler US composite index was strictly related to severity of rejection (P < .001). When applied retrospectively, this index had good accuracy (88%) for prediction of rejection (specificity, 89%; sensitivity, 86%; negative predictive value, 94%). CONCLUSION: During the first weeks after OLT, a marked decrease in PBV associated with increased SPI supports suspicion of clinically relevant acute rejection.

Change in portal flow after liver transplantation: effect on hepatic arterial resistance indices and role of spleen size.

Information on changes in splanchnic hemodynamics after liver transplantation is incomplete. In particular, data on long-term changes are lacking, and the relationship between changes in arterial and portal parameters is still under debate. The effect of liver transplantation on splanchnic hemodynamics was analyzed with echo-Doppler in 41 patients with cirrhosis who were followed for up to 4 years. Doppler parameters were also evaluated in 7 patients transplanted for acute liver failure and in 35 controls. In cirrhotics, portal blood velocity and flow increased immediately after transplantation (from 9.1 plus minus 3.7 cm/sec to 38.3 plus minus 14.6 and from 808 plus minus 479 mL/min to 2,817 plus minus 1,153, respectively, P <.001). Hepatic arterial resistance index (pulsatility index) also augmented (from 1.36 plus minus 0.32 to 2.34 plus minus 1.29, P <.001) and was correlated with portal blood velocity and flow. The early changes in these parameters were related, in agreement with the hepatic buffer response theory. Portal flow returned to normal values after 2 years. Superior mesenteric artery flow normalized after 3 to 6 months. Splenomegaly persisted after 4 years, when spleen size was related to portal blood flow. In 7 patients transplanted for acute liver failure, portal flow, and hepatic arterial resistance index were normal after transplantation. In conclusion, a high portal flow was present in cirrhotics until 2 years after transplantation, probably because of maintenance of elevated splenic flow. An early increase in hepatic arterial resistance indices is a common finding, but it is transient and is related to the increase in portal blood flow. A normal time course of portal-hepatic hemodynamics was detected in patients transplanted for acute liver failure.