Supramolecular chemotherapy is aimed to employ supramolecular approach for regulating the cytotoxicity and improving the efficiency of antitumor drugs. In this paper, we demonstrated a new example of supramolecular chemotherapy by utilizing the clinical antitumor drug, oxaliplatin, which is the specific drug for colorectal cancer treatment. Cytotoxicity of oxaliplatin to the colorectal normal cell could be significantly decreased by host-guest complexation between oxaliplatin and cucurbit[7]uril (CB[7]). More importantly, oxaliplatin-CB[7] exhibited cooperatively enhanced antitumor activity than oxaliplatin itself. On the one hand, the antitumor activity of oxaliplatin can reappear by competitive replacement of spermine from oxaliplatin-CB[7]; on the other hand, CB[7] can consume the overexpressed spermine in tumor environments, which is essential for tumor cell growth. These two events can lead to the cooperatively enhanced antitumor performance. Supramolecular chemotherapy can be applied to treat with spermine-overexpressed tumors. It is highly anticipated that this strategy may be employed in many other clinical antitumor drugs, which opens a new horizon of supramolecular chemotherapy for potential applications in clinical antitumor treatments.
Scale formation presents an enormous cost to the global economy. Classical nucleation theory dictates that to reduce the heterogeneous nucleation of scale, the surface should have low surface energy and be as smooth as possible. Past approaches have focused on lowering surface energy via the use of hydrophobic coatings and have created atomically smooth interfaces to eliminate nucleation sites, or both, via the infusion of lowsurface-energy lubricants into rough superhydrophobic substrates. Although lubricant-based surfaces are promising candidates for antiscaling, lubricant drainage inhibits their utilization. Here, we develop methodologies to deposit slippery omniphobic covalently attached liquids (SOCAL) on arbitrary substrates. Similar to lubricant-based surfaces, SOCAL has ultralow roughness and surface energy, enabling low nucleation rates and eliminating the need to replenish the lubricant. To enable SOCAL coating on metals, we investigated the surface chemistry required to ensure high-quality functionalization as measured by ultralow contact angle hysteresis (<3°). Using a multilayer deposition approach, we first electrophoretically deposit (EPD) silicon dioxide (SiO 2 ) as an intermediate layer between the metallic substrate and SOCAL. The necessity of EPD SiO 2 is to smooth (<10 nm roughness) as well as to enable the proper surface chemistry for SOCAL bonding. To characterize antiscaling performance, we utilized calcium sulfate (CaSO 4 ) scale tests, showing a 20× reduction in scale deposition rate than untreated metallic substrates. Descaling tests revealed that SOCAL dramatically decreases scale adhesion, resulting in rapid removal of scale buildup. Our work not only demonstrates a robust methodology for depositing antiscaling SOCAL coatings on metals but also develops design guidelines for the creation of antifouling coatings for alternate applications such as biofouling and high-temperature coking.
Corrosion
of metallic substrates is a problem for a variety of
applications. Corrosion can be mitigated with the use of an electrically
insulating coating protecting the substrate. Thick millimetric coatings,
such as paints, are generally more corrosion-resistant when compared
to nanoscale coatings. However, for thermal systems, thick coatings
are undesirable due to the resulting decrease in the overall heat
transfer stemming from the added coating thermal resistance. Hence,
the development of ultrathin (<10 μm) coatings is of great
interest. Ultrathin inorganic silicon dioxide (SiO2) coatings
applied by sol–gel chemistries or chemical vapor deposition,
as well as organic coatings such as Parylene C, have great anticorrosion
performance due to their high dielectric breakdown and low moisture
permeability. However, their application to arbitrarily shaped metals
is difficult or expensive. Here, we develop a sol–gel solution
capable of facile and controllable dip coating on arbitrary metals,
resulting in a very smooth (<5 nm roughness), thin (∼3 μm),
and conformal coating of dense SiO2. To benchmark our material,
we compared the corrosion performance with in-house synthesized superhydrophobic
aluminum and copper samples, Parylene C-coated substrates, and smooth
hydrophobic surfaces functionalized with a hydrophobic self-assembled
monolayer. For comparison with state-of-the-art commercial coatings,
copper substrates were coated with an organo-ceramic SiO2 layer created by an elevated temperature and atmospheric pressure
metal organic chemical vapor deposition process. To characterize corrosion
performance, we electrochemically investigated the corrosion resistance
of all samples through potentiodynamic polarization studies and electrochemical
impedance spectroscopy. To benchmark the coating durability and to
demonstrate scalability, we tested internally coated copper tubes
in a custom-built corrosion flow loop to simulate realistic working
conditions with shear and particulate saltwater flow. The sol–gel
and Parylene C coatings demonstrated a 95% decrease in corrosion rate
during electrochemical tests. Copper tube weight loss was reduced
by 75% for the sol–gel SiO2-coated tubes when seawater
was used as the corrosive fluid in the test loop. This work not only
demonstrates scalable coating methodologies for applying ultrathin
anticorrosion coatings but also develops mechanistic understanding
of corrosion mechanisms on a variety of functional surfaces and substrates.
Fouling
and accretion have negative impacts on a plethora of processes.
To mitigate heterogeneous nucleation of a foulant, lowering the surface
energy and reducing surface roughness are desired. Here, we develop
a multilayer coating to mitigate solution-based heterogeneous fouling
for internal flows. The first layer is a sol–gel silicon dioxide
(SiO2) coating, which acts as a corrosion barrier, creates
the surface chemistry needed for covalent bonding of the slippery
omniphobic covalently attached liquid (SOCAL), and ensures an atomically
smooth (<1 nm) interface. The second layer bonded to SiO2 is SOCAL, which further reduces the nucleation rate due to its low
surface energy (<12 mJ/m2). The presence of a consistent
sol–gel SiO2 base coating to bind to the SOCAL enables
application to various metallic substrates. The coating is solid,
making it more durable when compared to alternative slippery liquid-infused
surfaces (LIS) that suffer from lubricant loss. To demonstrate performance
and scalability, we apply our coating to the internal walls of aluminum
(Al) tubing and test its fouling performance in a flow-fouling setup
with single-phase flow of synthetic seawater. The seawater consists
of saturated calcium sulfide (CaSO4), and fouling is characterized
in both laminar and turbulent flow regimes (Reynolds numbers 1030
to 9300). Our coating demonstrated a reduction in salt scale fouling
by 95% when compared to uncoated Al tubes. Furthermore, we show our
coating to withstand turbulent flow conditions, mechanical abrasion
loading, and corrosive environments for durations much longer than
LIS. Our work demonstrates a coating methodology applicable to a variety
of metal substrates and internal passages to achieve antifouling in
single-phase flows.
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