Formulation & Performance — A18B8C14

DCL0018 · Updated 19 October 2026

Study context and evidence coverage

The PILL study generated 275 ionizable lipids using visible-light photochemistry. A18B8C14 was selected for in vivo mRNA delivery. This guide uses the supplied 49-page Supporting Information and the publisher abstract. Exact optimized/SORT recipes and numeric main-figure endpoints await the full article.

Literature results apply to the stated formulations and test conditions; they are not batch release specifications.

Four-component formulation screen

Study	Ionizable / helper / cholesterol / PEG-lipid	Total lipid:mRNA	Interpretation
S3a helper/PEG screen	50:10:38.5:1.5 mol%	20:1 w/w	DSPC + DMG-PEG2000 is one explicitly tested combination.
S3b ratio screen	50:10:38.5:1.5 or 35:16:46.5:2.5 mol%	10:1, 20:1 or 40:1 w/w	These are screening conditions. Helper/PEG identity for panel b is not specified in its caption.
SORT formulations	Not verified	Not verified	Abstract describes organ-selective delivery; exact recipes and effect sizes not assigned.

Source: SI S25 Fig. S3; publisher abstract.

Helper lipids screened in S3a: DOPE, POPE, DSPC, DOPC and ESM. PEG-lipids: DMG-PEG2000, C14-PEG2000-PE and C16-PEG2000-ceramide. N/P: not reported in the verified source. The total lipid:mRNA weight ratio must not be entered as N/P.

Component molecular weights and mass conversion

The following calculation uses the tested A18B8C14/DSPC/cholesterol/DMG-PEG2000 combination at 50:10:38.5:1.5 mol%. DMG-PEG2000 uses the catalog molecular weight 2507. Values are calculated, not experimental measurements.

Component	Molecular weight	mol%	Mass per 100 mg total lipid (mg)	Mass per 7.5 µg mRNA at 20:1 (µg)
A18B8C14	1003.77	50	65.404	98.105
DSPC	790.15	10	10.297	15.445
Cholesterol	386.65	38.5	19.399	29.098
DMG-PEG2000	2507	1.5	4.901	7.351

Mass fraction = (mole fraction × molecular weight) / Σ(mole fraction × molecular weight). Total lipid for 7.5 µg mRNA at 20:1 w/w is 150 µg. These are input amounts before purification; recovery and final concentration must be measured.

Preparation and characterization

Step / parameter	Reported method
RNA phase	7.5 µg mRNA in 20 mM citrate, pH 3.0.
Lipid phase and mixing	Lipids in ethanol; aqueous:organic 3:1 v/v; rapid pipette mixing. No microfluidic flow rate is specified.
Post-processing	Dilute in water, process with a 10K centrifugal ultrafilter to remove residual lipids/ethanol, then dilute concentrate in DPBS.
Particle characterization	DLS size/zeta potential; TEM morphology; RNA fluorescence assay for encapsulation. Exact zeta/EE values are not supplied here.
Apparent pKa	Fluorescence assay with a four-parameter sigmoid fit; midpoint at 50% normalized signal. Exact numerical pKa is unverified.
N/P	Not reported; no value inferred from mass ratio.

Source: SI S20.

Experiment-specific conditions

Experiment	Model / cargo / dose	Route and timing
In vitro reporter expression	HeLa, 10,000 cells/well; Fluc mRNA 50 ng/mL	Seed 24 h before exposure; readout after 24 h. This concentration is not 50 ng/well.
In vivo reporter expression	4-week male ICR CD-1 mice; Fluc mRNA 0.25 mg/kg	LNP IV; imaging after 6 h. Luciferin is administered IP for imaging.
Cre reporter method	Ai9 mice; Cre mRNA 0.25 mg/kg	Tail vein; tdTomato imaging and 10 µm sections after 2 days. A numerical recombination rate is not available.
Confocal imaging	HeLa; Cy5-mRNA LNP	4 h exposure; LysoTracker/Cy5 Pearson correlation.
Hemolysis method	Rat RBCs 1% v/v; total lipid 7 µM; pH 5.5 or 7.4	37 °C, 1 h; 0.5% Triton positive control. No unverified hemolysis percentage assigned.
CBC method	4-week male CD-1 mice; PBS, MC3 or PILL-LNP	IV; blood collection after 24 h. This timing is not automatically transferred to Fig. S9 chemistry.

Source: SI S21–S23.

Performance, stability and mechanistic evidence

Endpoint	Observation	Experimental context / source
Lead selection	The publication abstract identifies A18B8C14 as a lead and reports higher in vivo expression than the MC3 benchmark. The exact fold change and optimized/SORT compositions are not verified here.	Optimized A18B8C14 LNP versus MC3; abstract-level result only; Not available in abstract. Publisher abstract
Purified lipid validation	SI Fig. S5b shows stronger liver-associated luminescence for A18B8C14 than the C1/C8/C9 analogues in the displayed experiment; no image-derived fold change is assigned.	Fluc mRNA 0.25 mg/kg IV, male ICR CD-1 mice; n=4 for S5b; 6 h. SI S21, S27 Fig. S5b
Cellular uptake inhibition	Dynasore markedly reduces Cy5-positive uptake; other tested inhibitors show much smaller changes. The panel supports an inhibitor-sensitive uptake mechanism but does not uniquely prove a pathway.	HeLa; inhibitor pre-incubation 1 h, then Cy5-mRNA LNP exposure 1 h; 1 h LNP exposure. SI S23, S29 Fig. S7a–b
Endosomal colocalization	NH4Cl increases Cy5-mRNA/LysoTracker Pearson correlation; Fig. S7d marks P<0.01. This is colocalization evidence, not a measured escape percentage.	HeLa; fluorescence microscopy and Pearson correlation; 4 h general imaging protocol. SI S22, S29 Fig. S7c–d
Storage stability	Z-average remains approximately 150–165 nm and PDI approximately 0.06–0.17 during the displayed refrigerated series. Approximate visual readings, not tabulated values.	LNP suspension at 4 °C; caption specifies 30 days; 30-day study. SI S28 Fig. S6a
Freeze–thaw response	After the first cycle the plotted size is about 170 nm; subsequent cycles approach 180 nm. PDI rises to about 0.3. These observations do not establish retained mRNA expression.	−80 °C to room temperature; four cycles; approximate visual readings; 1–4 cycles. SI S20, S28 Fig. S6b
Dose-dependent blood chemistry	At 0.25 mg/kg all five displayed markers are marked ns versus saline. At 1 and 2 mg/kg GOT/AST and GPT/ALT increase significantly; creatinine is significantly elevated at 0.5, 1 and 2 mg/kg. ALP is marked ns at all doses.	Fluc-mRNA A18B8C14 LNP IV; 0.25, 0.5, 1 and 2 mg/kg; n=4. Blood-chemistry sampling time is not specified in Fig. S9.; Not specified for Fig. S9. SI S31 Fig. S9

Dose-dependent interpretation

Fig. S9 does not support an unrestricted “nontoxic” claim. Although the 0.25 mg/kg group is marked nonsignificant versus saline for the displayed markers, higher doses increase transaminases and creatinine. The experiment has n=4, and nonsignificance is not equivalence or clinical safety.

Structure, synthesis and analytical identity

The two secondary amines are connected by a five-carbon linker. Each arm contains an α-branched amine and a 2-hexyldecanoate ester. The structure and formula C65H130N2O4 are explicitly shown in S19. Four stereocenters are unassigned.

A18 (1,5-diaminopentane), B8 and C14 were reacted under 427 nm irradiation for 4 h at room temperature for this compound. The general procedure uses HFIP and catechol, followed by preparative chromatography. Formic acid/ammonium formate in the mobile phase does not establish an isolated formate salt.

Analytical record	Reported value / interpretation
Average molecular weight	1003.77 (SI S19); structure-based calculation agrees within rounding.
HRMS [M+H]+	Calculated 1004.0103; found 1004.0117.
HRMS [M+2H]2+	Calculated 502.5088; found 502.5067.
Research material HPLC	96.00% stated in S19; S48 UV 210 nm peak table gives 96.005%. This is not a DC Chemicals batch result or ELSD-HPLC measurement.
NMR / mass spectra	1H/13C NMR and HPLC S48; LRMS/HRMS S49.
Simulation	50 lipids, Martini 3 / GROMACS 2024, 1 µs. PILL +2 at modeled pH 5.5 is a simulation assumption, not a measured pKa or isolated salt assignment.

Source: SI S12, S19, S24, S48–S49.

References

Chun S, Nam H, Lee D, Lee Y, Park CH, Lim C, Kim D, Park JS, Kim KP, Choi HS, Koo H. Photochemistry-Based Development of Ionizable Lipid Library for mRNA-Lipid Nanoparticle Delivery In Vivo. Journal of the American Chemical Society. 2026;148(39):42494–42507. doi:10.1021/jacs.6c13674. Article and Supporting Information.